EPA's Denial of the Petitions To Reconsider the Endangerment and Cause or Contribute Findings for Greenhouse Gases Under Section 202(a) of the Clean Air Act

Federal RegisterAug 13, 2010

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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Chapter 1

[EPA-HQ-OAR-2009-0171; FRL-9184-8]

EPA's Denial of the Petitions To Reconsider the Endangerment and Cause or Contribute Findings for Greenhouse Gases Under Section 202(a) of the Clean Air Act

AGENCY:

Environmental Protection Agency (EPA).

ACTION:

Notice, denial of petitions to reconsider.

SUMMARY:

The Environmental Protection Agency (EPA) is denying the petitions to reconsider the Endangerment and Cause or Contribute Findings for Greenhouse Gases under Section 202(a) of the Clean Air Act. The Findings were signed by the Administrator on December 7, 2009. EPA has carefully reviewed all of the petitions and revisited both the scientific record and the Administrator's decision process underlying the Findings in light of these petitions. EPA's analysis of the petitions reveals that the petitioners have provided inadequate and generally unscientific arguments and evidence that the underlying science supporting the Findings is flawed, misinterpreted or inappropriately applied by EPA. The petitioners' arguments fail to meet the criteria for reconsideration under the Clean Air Act. The science supporting the Administrator's finding that elevated concentrations of greenhouse gases in the atmosphere may reasonably be anticipated to endanger the public health and welfare of current and future U.S. generations is robust, voluminous, and compelling, and has been strongly affirmed by the recent science assessment of the U.S. National Academy of Sciences.

DATES:

This denial is effective July 29, 2010.

ADDRESSES:

EPA's docket for this action is Docket ID No. EPA-HQ-OAR-2009-0171: All documents in the docket are listed on the

http://www.regulations.gov

Web site. Although listed in the index, some information is not publicly available,

e.g.,

confidential business information (CBI) or other information whose disclosure is restricted by statute. Certain other material, such as copyrighted material, is not placed on the Internet and will be publicly available only in hard copy form. Publicly available docket materials are available either electronically through

http://www.regulations.gov

or in hard copy at EPA's Docket Center, Public Reading Room, EPA West Building, Room 3334, 1301 Constitution Avenue, NW., Washington, DC 20004. This Docket Facility is open from 8:30 a.m. to 4:30 p.m., Monday through Friday, excluding legal holidays. The telephone number for the Public Reading Room is (202) 566-1744, and the telephone number for the Air Docket is (202) 566-1742.

FOR FURTHER INFORMATION CONTACT:

Jeremy Martinich, Climate Change Division, Office of Atmospheric Programs (MC-6207J), Environmental Protection Agency, 1200 Pennsylvania Ave., NW., Washington, DC 20460; telephone number: (202) 343-9927; fax number: (202) 343-2202; e-mail address:

ghgendangerment@epa.gov.

For additional information regarding this Notice, please go to the Web site

http://www.epa.gov/climatechange/endangerment.html.

SUPPLEMENTARY INFORMATION:

Acronyms and Abbreviations.

The following acronyms and abbreviations are used in this Decision.

ACUS Administrative Conference of the United States

ANPR Advance Notice of Proposed Rulemaking

APA Administrative Procedure Act

CAA Clean Air Act

CAFE Corporate Average Fuel Economy

CAIT Climate Analysis Indicators Tool

CBI confidential business information

CCSP Climate Change Science Program

CFR Code of Federal Regulations

methane

carbon dioxide

CRU Climatic Research Unit

DOT U.S. Department of Transportation

EISA Energy Independence and Security Act

EO Executive Order

EPA U.S. Environmental Protection Agency

EPCA Energy Policy and Conservation Act

FOIA Freedom of Information Act

FR Federal Register

GHG greenhouse gas

HadCRUT Climatic Research Unit (CRU) temperature record

ICTA International Center For Technology Assessment

IPCC Intergovernmental Panel on Climate Change

MWP Medieval Warm Period

O nitrous oxide

NAAQS National Ambient Air Quality Standards

NAS National Academy of Sciences

NASA National Aeronautics and Space Administration

NHTSA National Highway Traffic Safety Administration

NOAA National Oceanic and Atmospheric Administration

nitrogen oxide

NRC National Research Council

NSPS new source performance standards

PM particulate matter

PSD Prevention of Significant Deterioration

TSD technical support document

U.S. United States

UNFCCC United Nations Framework Convention on Climate Change

USGCRP U.S. Global Change Research Program

WMO World Meteorological Organization

Table of Contents

I. Introduction

A. Summary

B. Background

1. The ICTA Petition and

Massachusetts

EPA

Post-Massachusetts

EPA

3. Proposed and Final Endangerment and Cause or Contribute Findings

4. Petitions for Reconsideration and Stay Requests

II. Standard for Reconsideration

III. Science Related Issues

A. General Summary of Petitioners' Arguments

B. Summary of the Science Underlying the Administrator's Endangerment Finding in Light of the Petitioners' Claims

1. What effects do greenhouse gases have on the environment and on climate in particular?

2. How are human activities changing the amount of greenhouse gases in our atmosphere?

3. What is the evidence indicating that average temperatures are increasing and climate change is occurring consistent with the direction one would expect with increasing greenhouse gases in our atmosphere?

4. What is the evidence linking observed temperature changes and climate change to the anthropogenic increase in greenhouse gases?

5. How are public health and welfare threatened by these changes to climate and the environment, now and in the future?

C. Review of the Administrator's Findings

D. General Response to the Petitioners' Scientific Arguments in Light of the Full Body of Scientific Evidence

E. Specific Responses to the Claims and Arguments Raised by Petitioners

1. Climate Science and Data Issues Raised by the Petitioners

2. Issues Raised by EPA's Use of the IPCC AR4 Assessment

3. Process and Other Issues Raised by the Petitioners

F. Petitioners' Arguments Do Not Meet the Standard for Reconsideration

IV. Other Issues

A. The Tailoring Rule/Impacts of PSD and Title V Permitting Are Not of Central Relevance to the Findings

B. NHTSA Rule

C. Other Issues

1. Effects of the Findings and Subsequent Rulemakings on States and Businesses

2. A Formal Rulemaking Process Is Not Required

3. Discretion in Making an Endangerment Finding

V. Conclusion

I. Introduction

A. Summary

This is EPA's response denying the petitions to reconsider the Endangerment and Cause or Contribute Findings for Greenhouse Gases under Section 202(a) of the Clean Air Act (“Findings” or the “Endangerment Finding”) (74 FR 66496, December 15, 2009). EPA has considered all 10 petitions, including the arguments presented therein and the supplemental information provided by the petitioners as supporting evidence of their claims. EPA has evaluated the merit of the petitioners' arguments in the context of the entire body of scientific and other evidence before the Agency. This response (hereafter “Denial” or “Decision”) provides EPA's scientific and legal justification for denying these petitions. This Denial is accompanied by a 3-volume, roughly 360-page Response to Petitions (RTP) document (

http://www.epa.gov/climatechange/endangerment.html

), containing further responses and technical detail concerning every significant claim and assertion made by the petitioners. Section III of this Decision summarizes many of the responses provided in the RTP document.

After a comprehensive, careful review and analysis of the petitions, EPA has determined that the petitioners' arguments and evidence are inadequate, generally unscientific, and do not show that the underlying science supporting the Endangerment Finding is flawed, misinterpreted by EPA, or inappropriately applied by EPA. The science supporting the Administrator's finding that elevated concentrations of greenhouse gases in the atmosphere may reasonably be anticipated to endanger the public health and welfare of current and future U.S. generations is robust, voluminous, and compelling. The most recent science assessment by the U.S. National Academy of Sciences strongly affirms this view. In addition, the approach and procedures used by EPA to evaluate the underlying science demonstrate that the Findings remain robust and appropriate.

Petitioners generally argue that recent revelations show that the science supporting EPA's Endangerment Finding was flawed or questionable, and that EPA should therefore reconsider the Endangerment Finding. The petitioners' arguments and claims are based largely on disclosed private communications among various scientists, a limited number of errors and claimed errors in the 2007 Intergovernmental Panel on Climate Change (IPCC) Fourth Assessment Report (AR4),

and submissions of a limited number of additional studies not previously considered as part of the scientific record of the Endangerment Finding.

IPCC (2007). Fourth Assessment Report: Climate Change 2007. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA.

As discussed in detail throughout this Decision and in fuller detail in the RTP document, petitioners' claims and the information they submit do not change or undermine our understanding of how anthropogenic emissions of greenhouse gases cause climate change and how human-induced climate change generates risks and impacts to public health and welfare. This understanding has been decades in the making and has become more clear over time with the accumulation of evidence. The information provided by petitioners does not change any of the scientific conclusions that underlie the Administrator's Findings, nor do the petitions lower the degrees of confidence associated with each of these major scientific conclusions.

More specifically, the petitions do not change EPA's proper characterization of the current body of knowledge and our ability to state with confidence our conclusions in the following key areas of greenhouse gas and climate change science: (1) That anthropogenic emissions of greenhouse gases are causing atmospheric levels of greenhouse gases in our atmosphere to rise to essentially unprecedented levels in human history; (2) that the accumulation of greenhouse gases in our atmosphere is exerting a warming effect on the global climate; (3) that there are multiple lines of evidence, including increasing average global surface temperatures, rising ocean temperatures and sea levels, and shrinking Arctic ice, all showing that climate change is occurring, and that the observed rate of climate change stands out as significant compared to recent historical rates of climate change; (4) that there is compelling evidence that anthropogenic emissions of greenhouse gases are the primary driver of recent observed increases in average global temperature; (5) that atmospheric levels of greenhouse gases are expected to continue to rise for the foreseeable future; and (6) that risks and impacts to public health and welfare are expected to grow as climate change continues, and that climate change over this century is expected to be greater compared to observed climate change over the past century.

The core defect in petitioners' arguments is that these arguments are not based on consideration of the body of scientific evidence. Petitioners fail to address the breadth and depth of the scientific evidence and instead rely on an assumption of inaccuracy in the science that they extend even to the body of science that is not directly addressed by information they provide or by arguments they make. This assumption of error is based on various statements and views expressed in some of the e-mail communications between scientists at the Climatic Research Unit (CRU) of the University of East Anglia in the United Kingdom and several other scientists (“the CRU e-mails”)

. As EPA's review and analysis shows, the petitioners routinely take these private e-mail communications out of context and assert they are “smoking gun” evidence of wrongdoing and scientific manipulation of data. EPA's careful examination of the e-mails and their context shows that the petitioners' claims are exaggerated, are often contradicted by other evidence, and are not a material or reliable basis to question the validity and credibility of the body of science underlying the Administrator's Endangerment Finding or the Administrator's decision process articulated in the Findings themselves Petitioners' assumptions and subjective assertions regarding what the e-mails purport to show about the state of climate change science are clearly inadequate pieces of evidence to challenge the voluminous and well documented body of science that is the technical foundation of the Administrator's Endangerment Finding.

All of the disclosed CRU e-mails at issue in this Decision can be found in full in EPA's docket for the Endangerment Finding. See Docket ID No. EPA-HQ-OAR-2009-0171, “CRU E-mails 1996-2009.”

Inquiries from the UK House of Commons, Science and Technology Committee, the University of East Anglia, Oxburgh Panel, the Pennsylvania State University, and the University of East Anglia, Russell Panel,

all entirely independent from EPA, have examined the issues and many of the same allegations brought forward by the petitioners as a result of the disclosure of the private CRU e-mails. These inquiries are now complete. Their conclusions are in line with EPA's review and analysis of these same CRU e-mails. The inquiries have

found no evidence of scientific misconduct or intentional data manipulation on the part of the climate researchers associated with the CRU e-mails. The recommendation for more transparent procedures concerning availability of underlying data appears appropriate, but it has not cast doubt on the underlying body of science developed by these researchers. These inquiries lend further credence to EPA's conclusion that petitioners' claims that the CRU e-mails show the underlying science cannot or should not be trusted are exaggerated and unsupported.

These inquires plus another addressing IPCC AR4 issues are referred to throughout this Decision and the RTP document. Every inquiry is provided in full in EPA's docket for the Endangerment Finding. See Docket ID No. EPA-HQ-OAR-2009-0171, “Recent Inquiries and Investigations of the CRU E-mails and the IPCC Fourth Assessment Report.”

Petitioners' also point to a limited number of factual mistakes in IPCC AR4, some confirmed, some alleged, to argue that the climate science supporting the Administrator's Endangerment Finding is flawed. EPA's review confirmed two factual mistakes. These two confirmed instances of factual mistakes are tangential and minor and do not change the key IPCC AR4 conclusions that are central to the Administrator's Endangerment Finding. While it is unfortunate that IPCC's review process did not catch these errors, in the context of a report of this size and scope (almost 3,000 pages), it is an inappropriate and unfounded exaggeration to claim that these two confirmed mistakes delegitimize all of the scientific statements and findings contained in IPCC AR4. To the contrary, given the scrutiny to which IPCC AR4 has been subjected, the limited nature of these mistakes demonstrates that the IPCC review procedures have been highly effective and very robust.

In a limited number of cases, the petitioners identify new scientific studies and data, published since the Endangerment Finding was finalized, which they claim require EPA to reconsider the Endangerment Finding. Some petitioners also argue that EPA ignored or misinterpreted scientific data that were significant and available when the Finding was made. EPA's review of these claims shows that in many cases the issues raised by the petitioners are not new, but were in fact considered prior to issuing the Endangerment Finding. In other cases, the petitioners have misinterpreted or misrepresented the meaning and significance of recent scientific literature, findings, and data. Finally, there are instances in which the petitioners have failed to acknowledge other new studies in making their arguments. The RTP document contains study-by-study analysis of these failed arguments on the part of petitioners.

Finally, in May 2010, the National Research Council (NRC) of the U.S. National Academy of Sciences published its comprehensive assessment, “Advancing the Science of Climate Change

” (NRC, 2010). It concluded that “climate change is occurring, is caused largely by human activities, and poses significant risks for—and in many cases is already affecting—a broad range of human and natural systems.” Furthermore, the NRC stated that this conclusion is based on findings that are “consistent with the conclusions of recent assessments by the U.S. Global Change Research Program, the Intergovernmental Panel on Climate Change's Fourth Assessment Report, and other assessments of the state of scientific knowledge on climate change.” These are the same assessments that served as the primary scientific references underlying the Administrator's Endangerment Finding. Importantly, this recent NRC assessment represents another independent and critical inquiry of the state of climate change science, separate and apart from the previous IPCC and U.S. Global Change Research Program (USGCRP) assessments. The NRC assessment is a clear affirmation that the scientific underpinnings of the Administrator's Endangerment Finding are robust, credible, and appropriately characterized by EPA.

National Research Council (NRC) (2010). Advancing the Science of Climate Change. National Academy Press. Washington, DC.

The endangerment to public health and welfare from atmospheric concentrations of greenhouse gases and associated climate change is too important an issue to be decided on any grounds other than a close and comprehensive scrutiny of the entire body of the scientific evidence. This principle calls for an outright rejection of the petitioners' arguments. The petitioners' arguments amount to a request that EPA ignore the deep body of science that has been built up over several decades and the direction it points in, and to do so based not on a careful and comprehensive analysis of the science, but instead on what amount to assertions and leaps in logic, unsupported by a rigorous examination of the science itself. The petitioners do not provide any substantial support for the argument that the Endangerment Finding should be revised. Therefore, none of the petitioners' objections are of central relevance to the considerations that led to the final Endangerment Finding. In addition, in many cases these arguments by the petitioners either were or could have been raised during the comment period on the Endangerment Finding. In summary, EPA's thorough review of petitioners' arguments shows that the petitioners have not met the criteria for reconsideration under section 307(d) the Clean Air Act (CAA).

Some petitioners also raise objections to EPA's Endangerment Finding based on legal arguments related to other EPA or National Highway Traffic Safety Administration actions. For the reasons discussed in Section IV of this Decision, those objections also fail to meet the standard for reconsideration and are denied.

B. Background

The Findings were signed by the Administrator on December 7, 2009, were published in the

Federal Register

on December 15, 2009, and became effective January 14, 2010. The Administrator's Endangerment Finding concluded that atmospheric concentrations of the group of six greenhouse gases are reasonably anticipated to endanger both the public health and public welfare of current and future U.S. generations. The Administrator also decided that the combined emissions of greenhouse gases from new motor vehicles and new motor vehicle engines contribute to the greenhouse gas air pollution that endangers both public health and public welfare (

i.e.,

the second finding or “cause or contribute” finding). These Findings were made under CAA section 202(a). The Findings were also supported by a Technical Support Document (TSD) (Docket EPA-HQ-OAR-2009-0171-11645), containing the underlying greenhouse gas emissions data and a synthesis of climate change science, as well as an 11-volume RTC document (Docket EPA-HQ-OAR-2009-0171) that provides EPA's responses to all significant public comments that had been received during the 60-day public comment period following the Administrator's proposed Findings, signed April 17, 2009.

Since finalization of the Findings in December 2009, EPA has received 10 petitions and supplements thereto requesting that EPA reconsider the Findings. The general bases of the petitions are the following: (1) Recent disclosure of private e-mail communications among some scientists who were involved in constructing one of the global temperature records and were involved in certain sections of IPCC AR4; (2) alleged and confirmed mistakes or alleged unsupported statements in the IPCC AR4; and (3) some new scientific studies not previously considered as part of the scientific record of the Endangerment Finding. Petitioners claim these pieces of evidence show that the science underlying the Administrator's Endangerment Finding is potentially

flawed, and that therefore EPA should reopen the process and reconsider the Endangerment Finding. For reasons stated above and throughout this Decision and accompanying RTP document, EPA is denying the request to reconsider the Findings.

As discussed further in sections III and IV of this Decision, some of the objections raised in the petitions fail to demonstrate that it was impracticable to raise the objections during the comment period following the proposed Findings, or that the grounds for the objections arose after the period for judicial review. For all issues and arguments presented by the petitioners, the objections are not of central relevance to the outcome of the Findings, as explained in detail below. Thus, none of the objections meet the criteria for reconsideration under the CAA. EPA is also denying two requests to stay the Findings pending reconsideration.

1. The ICTA Petition and Massachusetts v. EPA

a. ICTA Petition

In October 1999, the International Center for Technology Assessment (ICTA) and 18 other organizations filed a petition with EPA, requesting that EPA issue emission standards for emissions of carbon dioxide, methane, nitrous oxide, and hydrofluorocarbons from motor vehicles under CAA section 202(a) (ICTA Petition). The ICTA Petition alleged that emissions of these four greenhouse gases—CO

, CH

, N

O, and HFCs—constituted emissions of “air pollutants” under section 302(g) of the Act, 42 U.S.C. 7602(g). The ICTA Petition further argued that emissions of these gases from motor vehicles fully met the criteria for regulation under CAA section 202(a)(1), 42 U.S.C. 7521(a)(1), and claimed that it would be feasible for EPA to regulate greenhouse gas emissions from mobile sources.

After soliciting and considering approximately 50,000 public comments on the ICTA Petition,

see

66 FR 7486, January 23, 2001), the Agency ultimately denied it on several independent grounds. EPA first explained that Congress did not intend in the CAA to provide the Agency with authority to regulate CO

and other greenhouse gases to address global climate change (68 FR 52925-29). For a variety of reasons, EPA determined that it was unreasonable to read the Act as providing the Agency with authority to regulate emissions of CO

and other greenhouse gases to address global climate change.

Id.

at 52928. Based on this conclusion, the Agency also determined that greenhouse gases could not be considered air pollutants for purposes of the CAA's regulatory provisions for any contribution they may make to climate change.

Id.

The Agency also explained why, even if it had the authority to issue such regulations, it still believed that the ICTA Petition should be denied. To begin with, EPA found that requiring passenger cars and light trucks to emit less CO

, the predominant greenhouse gas, would be tantamount to imposing more stringent fuel economy standards on those vehicles.

Id.

at 52929. The Agency pointed out, however, that the Energy Policy and Conservation Act (EPCA) authorizes only the Department of Transportation (DOT) to increase the stringency of motor vehicle fuel economy standards, and specifies a detailed regulatory regime that an EPA requirement to significantly reduce motor vehicle CO

emissions would unavoidably abrogate.

Id.; see

also

49 U.S.C. 32902 (relevant provision of EPCA).

EPA also disagreed with the petitioners' view that, assuming the Act gives EPA authority to regulate CO

and other greenhouse gases to address global climate change, the Agency had already made statements that triggered a mandatory duty to issue motor vehicle standards for CO

and other greenhouse gases (68 FR 52929, September 8, 2003). After summarizing the findings of a 2001 report on global climate change by the National Academy of Sciences (NAS), the Agency concluded that “[u]ntil more is understood about the causes, extent and significance of climate change and the potential options for addressing it, EPA believes it is inappropriate to regulate [greenhouse gas] emissions from motor vehicles.”

Id.

at 52,931.

Massachusetts

EPA

EPA's initial denial of the ICTA petition (68 FR 52922, September 8, 2003) was the basis for the U.S. Supreme Court's decision in

Massachusetts

EPA,

549 U.S. 497 (2007). In

Massachusetts

EPA,

the Supreme Court held that EPA had improperly denied the petition. The Court held that greenhouse gases meet the definition of air pollutant in the CAA, and that the grounds EPA gave for denying the petition were “divorced from the statutory text” and hence improper. Specifically, the Court held that carbon dioxide, methane, nitrous oxide, and hydrofluorocarbons fit the CAA's “sweeping definition of ‘air pollutant’ ” since they are “without a doubt ‘physical [and] chemical * * * substances which [are] emitted into * * * the ambient air.’ The statute is unambiguous.”

Id.

at 529. The Court also rejected the argument that EPA could not regulate motor vehicle emissions of the chief greenhouse gas, carbon dioxide, because doing so would essentially require control of vehicle fuel economy, and Congress delegated that authority to the Department of Transportation in the Energy Policy and Conservation Act. The Court held that the fact “that DOT sets mileage standards in no way licenses EPA to shirk its environmental responsibilities. EPA has been charged with protecting the public's ‘health’ and ‘welfare,’ 42 U.S.C. 7521(a)(1), a statutory obligation wholly independent of DOT's mandate to promote energy efficiency.”

Id.

at 532 (citation omitted). The two obligations may overlap “but there is no reason to think the two agencies cannot both administer their obligations and yet avoid inconsistency.”

Id.

Turning to EPA's alternative grounds for denial, the Court held that EPA's decision on whether or not to grant the petition must relate to “whether an air pollutant `causes, or contributes to, air pollution which may reasonably be anticipated to endanger public health or welfare.’ ”

Id.

at 532-33. Thus, “[u]nder the clear terms of the Clean Air Act, EPA can avoid taking further action only if it determines that greenhouse gases do not contribute to climate change or if it provides some reasonable explanation as to why it cannot or will not exercise its discretion to determine whether they do.”

Id.

at 533. The Court held that three of the four reasons EPA advanced as alternative grounds for denying the petition were unrelated to whether greenhouse gas emissions from new motor vehicles cause or contribute to air pollution that may reasonably be anticipated to endanger public health or welfare. Thus, EPA had failed to offer a reasoned explanation for its action. The Court further held that EPA's generalized concerns about scientific uncertainty were likewise insufficient unless “the scientific uncertainty is so profound that it precludes EPA from making a reasoned judgment as to whether greenhouse gases contribute to global warming,” in which case EPA must so find.

Id.

at 534.

The Supreme Court was careful to note that it was not dictating EPA's action on remand, and was not deciding whether or not EPA must find that greenhouse gases endanger public health or welfare. Nor did the Court rule on “whether policy concerns can inform EPA's actions in the event that it makes such a finding.”

Id.

at 534-35. The Court also observed that under CAA section 202(a), “EPA no doubt has significant latitude as to the manner, timing,

content, and coordination of its regulations with those of other agencies.”

Id.

at 533. Nonetheless, any EPA decisions concerning the endangerment and cause or contribute criteria must be grounded in the requirements of CAA section 202(a).

On September 17, 2007, EPA's denial of the ICTA petition was vacated and remanded to EPA for further proceedings consistent with the Supreme Court's opinion.

Post-Massachusetts

EPA

In response to a May 2007 Executive Order (EO 13432) and instructions from then-President Bush, EPA began working closely with the Departments of Transportation, Energy and Agriculture to develop, under the CAA, proposals for greenhouse gas standards for motor vehicles and renewable and alternative fuel requirements for gasoline.

However, after enactment of the Energy Independence and Security Act of 2007 (EISA) in late December 2007, work in response to the Supreme Court's decision shifted. Rather than moving forward with the proposed endangerment determination and attendant greenhouse gas vehicle standards under the CAA, EPA developed an Advance Notice of Proposed Rulemaking (ANPR) on “Regulating Greenhouse Gas Emissions under the Clean Air Act,” which was published on July 30, 2008 (73 FR 44354). The ANPR presented information relevant to, and solicited public comment on, a wide variety of issues regarding the potential regulation of greenhouse gases under the CAA, including EPA's response to the Supreme Court's decision in

Massachusetts

EPA.

Section V of the ANPR contained an earlier version of much of the material in the Findings, including the legal framework, a summary of the science of climate change, and an illustration of how the Administrator could analyze the cause or contribute element using information regarding the greenhouse gas emissions of the portion of the U.S. transportation sector covered by CAA section 202(a). A July 2008 version of the TSD for the endangerment finding was also in the docket for the ANPR (EPA-HQ-OAR-2008-0318).

The comment period for the ANPR was 120 days, and it provided an opportunity for EPA to hear from the public with regard to the issues involved in endangerment and cause or contribute findings, as well as the supporting science. EPA received, reviewed, and considered numerous comments at that time and this public input was reflected in the Findings that the Administrator proposed in April 2009. In addition, many comments were received on the TSD released with the ANPR. These comments are reflected in revisions to the TSD that was released in April 2009 to accompany the Administrator's proposal.

3. Proposed and Final Endangerment and Cause or Contribute Findings

In April 2009, the Administrator proposed to find under CAA section 202(a) that the mix of six key greenhouse gases in the atmosphere may reasonably be anticipated to endanger public health and welfare. Specifically, the Administrator proposed to define the “air pollution” referred to in CAA section 202(a) to be the mix of six key directly emitted and long-lived greenhouse gases: Carbon dioxide, methane, nitrous oxide, hydrofluorocarbons, perfluorocarbons, and sulfur hexafluoride (74 FR 18886, April 24, 2009). The Administrator further proposed to find that combined greenhouse gas emissions from new motor vehicles and new motor vehicle engines contribute to this air pollution that endangers public health and welfare.

The Administrator's proposal was subject to a 60-day public comment period, which ended June 23, 2009, and also included two public hearings. Over 380,000 public comments were received on the Administrator's proposed endangerment and cause or contribute findings, including comments on the elements of the Administrator's April 2009 proposal, the legal issues pertaining to the Administrator's decisions, and the underlying TSD containing the scientific and technical information.

After carefully reviewing the public comments and all the information before her, on December 7, 2009, the Administrator signed the final Findings (74 FR 66496, December 15, 2009). Specifically, she found under CAA section 202(a) that atmospheric concentrations of the six greenhouse gases taken in combination may reasonably be anticipated to endanger both the public health and the public welfare of current and future generations. The Administrator also found that the combined emissions of these greenhouse gases from new motor vehicles and new motor vehicle engines contribute to the greenhouse gas air pollution that endangers public health and welfare under CAA section 202(a).

The July 2008 ANPR and the April 2009 proposed Findings were accompanied by draft versions of the TSD and the Findings were supported by the final TSD. The TSD provided an overview of all the major scientific assessments available at the time of each action, and greenhouse gas emission inventory data relevant to the contribution finding. Each of these three versions of the TSD were subject to review by Federal climate experts to ensure that they represented an accurate summary of the major scientific assessments. Moreover, the July 2008 and the April 2009 versions of the TSD were subject to public review as part of the public comment periods for the ANPR and proposed Findings.

4. Petitions for Reconsideration and Stay Requests

Between December 2009 and March 2010, EPA received 10 petitions (and supplements thereto) to reconsider the Findings.

Nine of these petitions base their requests on allegations that developments since the close of the comment period on the proposed Findings call into question the science underlying the Findings. One petition focuses on statements since the close of the comment period regarding the impact of regulating stationary sources under the CAA, and the relationship between EPA's proposed Light-Duty Vehicle Rule (see below) and the National Highway Transportation Safety Administration's (NHTSA) proposed Corporate Average Fuel Economy (CAFE) rule as a basis for their request that EPA reconsider the Findings. Each significant objection in the petitions is discussed in detail below and the accompanying RTP document. Note that when more than one petitioner raised an objection, our response to that objection is provided only once.

The West Virginia Coal Association also filed a letter in support of the existing petitions for reconsideration.

In addition, EPA received two requests to administratively stay the final Findings. One administrative stay request under CAA section 307(d)(7)(b) was tied to a petition to reconsider the findings based on concerns about the science and requested that EPA stay the final Findings for three months. The other administrative stay request was filed under CAA section 307(d)(7)(B), the Administrative Procedures Act (APA) section 705, and Federal Rule of Appellate Procedure 18(a)(1) as part of the petition for reconsideration relating to stationary source concerns, and requested a stay pending EPA's completion of its reconsideration of the final Findings.

II. Standard for Reconsideration

Section 307(d)(7)(B) of the CAA strictly limits petitions for

reconsideration both in time and scope. It states that: “Only an objection to a rule or procedure which was raised with reasonable specificity during the period for public comment (including any public hearing) may be raised during judicial review. If the person raising an objection can demonstrate to the Administrator that it was impracticable to raise such objection within such time or if the grounds for such objection arose after the period for public comment (but within the time specified for judicial review) and if such objection is of central relevance to the outcome of the rule, the Administrator shall convene a proceeding for reconsideration of the rule and provide the same procedural rights as would have been afforded had the information been available at the time the rule was proposed. If the Administrator refuses to convene such a proceeding, such person may seek review of such refusal in the United States court of appeals for the appropriate circuit (as provided in subsection (b)). Such reconsideration shall not postpone the effectiveness of the rule. The effectiveness of the rule may be stayed during such reconsideration, however, by the Administrator or the court for a period not to exceed three months.”

Thus the requirement to convene a proceeding to reconsider a rule is based on the petitioner demonstrating to EPA: (1) That it was impracticable to raise the objection during the comment period, or that the grounds for such objection arose after the comment period but within the time specified for judicial review (i.e., within 60 days after publication of the final rulemaking notice in the

Federal Register

, see CAA section 307(b)(1); and (2) that the objection is of central relevance to the outcome of the rule.

As to the first procedural criterion for reconsideration, a petitioner must show why the issue could not have been presented during the comment period, either because it was impracticable to raise the issue during that time or because the grounds for the issue arose after the period for public comment (but within 60 days of publication of the final action). Thus, CAA section 307(d)(7)(B) does not provide a forum to request EPA to reconsider issues that actually were raised, or could have been raised, prior to promulgation of the final rule.

In EPA's view, an objection is of central relevance to the outcome of the rule only if it provides substantial support for the argument that the regulation should be revised. See Denial of Petition to Reconsider, 68 FR 63021 (November 7, 2003), Technical Support Document for Prevention of Significant Deterioration (PSD) and Nonattainment New Source Review (NSR): Reconsideration at 5 (Oct. 30, 2003) (EPA-456/R-03-005) (available at

http://www.epa.gov/nsr/documents/petitionresponses10-30-03.pdf);

Denial of Petition to Reconsider NAAQS for PM, 53 FR 52698, 52700 (December 29, 1988), citing Denial of Petition to Revise NSPS for Stationary Gas Turbines, 45 FR 81653-54 (December 11, 1980), and decisions cited therein.

This interpretation is clearly appropriate in light of the criteria adopted by Congress in this and other provisions in section 307(d). Section 307(d)(4)(B)(i) provides that “[a]ll documents which become available after the proposed rule has been published and which the Administrator determines are of central relevance to the rulemaking shall be placed in the docket as soon as possible after their availability.” This provision draws a distinction between comments and other information submitted during the comment period, and other documents which become available after publication of the proposed rule. The former are docketed irrespective of their relevance or merit, while the latter must be docketed only if a higher hurdle of central relevance to the rulemaking is met. Congress also used the phrase “central relevance” in sections 307(d)(7)(B) and (d)(8), and in both cases Congress set a more stringent hurdle than in section 307(d)(4). Under section 307(d)(7)(B), the Administrator is required to reconsider a rule only if the objection is “of central relevance to the outcome of the rule.” Likewise, section 307(d)(8) authorizes a court to invalidate a rule for procedural errors only if the errors were “so serious and related to matters of such central relevance to the rule that there is a substantial likelihood that the rule would have been substantially changed if such errors had not been made.” In both of these provisions, it is not enough that the objection or error be of central relevance to the issues involved in the rulemaking, as in section 307(d)(4). Instead, the objection has to be of central relevance “to the outcome of the rule” itself, and the procedural error has to be of such central relevance that it presents a “substantial likelihood that the rule would have been substantially changed.” Central relevance to the issues involved in the rulemaking is not enough to meet the criteria Congress set under sections 307(d)(7) or (d)(8). Both of those provisions require that the objection or error be central to the substantive decision that is the outcome of the rulemaking. This difference is significant, and indicates that Congress set a much higher hurdle for disturbing a final rule that has already been issued, as compared to the less stringent criteria for docketing of documents before a decision has been made and a rule has been issued.

In this context, EPA's interpretation of section 307(d)(7)(B) gives full and appropriate meaning to the criteria adopted by Congress. An objection is considered of central relevance to the outcome of the rule only if it provides substantial support for the argument that the regulation should be revised. This properly links the criteria to the outcome of the rulemaking, not just the issues in the rulemaking. It requires that the objection be of such substance and merit that it can be considered central to the outcome of the rulemaking. This interpretation is consistent with section 307(d)(8), which also ties central relevance to the outcome of the rulemaking, in terms of a “substantial likelihood” that the rule would be “substantially changed.” This interpretation gives proper weight to the approach throughout section 307(b) and (d) of the importance Congress attributed to preserving the finality of agency rulemaking decisions. This interpretation is also consistent with the case law, as discussed below.

As discussed in this Decision, EPA is denying the petitions because they fail to meet these criteria. In many cases, the objections raised in the petitions to reconsider were or could have been raised during the comment period of the proposed Findings. In all cases, the objections are not of central relevance to the outcome of the rule because they do not provide substantial support for the argument that the Endangerment Finding should be revised.

Pacific Legal Foundation (PLF) argues that its objections are of central relevance because the CRU documents and e-mails “cast substantial uncertainty over” the final Endangerment Finding, and that EPA is required to grant the petition or reconsider “if information not available in the rulemaking record for public comment casts substantial uncertainty over the final regulation.” PLF Pet at 8-9. They argue that this is the case even if one does not assume or even argue that the statements in the CRU documents and e-mails are true. PLF Pet. at 6. They base this claim on

Kennecott Corp.

EPA,

684 F.2d 1007, 1017-20 (DC Cir. 1982).

PLF's view of

Kennecott

fails to account for the specific procedural issues that were central to that case. In

Kennecott,

petitioners objected that EPA had not provided adequate notice and

an opportunity for comment in the underlying rulemaking, in violation of various CAA section 307(d) provisions. Petitioners had two different notice and comment objections. First, they objected to EPA's failure to include certain documents in the docket at the time of the proposal, including various EPA financial analyses performed prior to the proposal. The court found that these documents were part of the basis for the proposed regulations and needed to be docketed so comment could be taken on them during the comment period. The court found that the failure to submit these documents to the docket at the time of the proposal was a procedural violation of CAA section 307(d)'s notice and comment requirements, because the documents EPA failed to docket made impossible any meaningful comment on the merits of EPA's proposal. The missing documents led to uncertainty over EPA's basis for the proposal, which the documents could clarify. This procedural violation met the test under CAA section 307(d)(9) for reversible error, because it indicated a “substantial likelihood” that the regulations would “have been significantly changed.”

Kennecott,

684 F.2d at 1018-1019.

It is this discussion of uncertainty that is cited by PLF. However this concerns the criteria for reversible error under CAA section 307(d)(9)(D)(iii) for a procedural violation. The court did not address this as the test for CAA section 307(d)(7)(B), and certainly did not do so for cases where there is no procedural violation.

Petitioners in

Kennecott

also objected to EPA's submission to the docket, one week prior to promulgation of the final rule, of certain economic forecast data upon which EPA relied for the final rule, where the forecast data differed significantly from the forecast data provided during the pubic comment period. The court found that this late submission of important information relied on by EPA, without an opportunity to comment, also violated the notice and comment requirements of CAA section 307(d).

Id.

at 1019.

Given these two violations of the notice and comment requirements of CAA section 307(d), the court determined that consideration of a petition to reconsider after promulgation of the final rule was not an adequate substitute for the statutory required notice and opportunity to comment prior to promulgation of the rule. EPA failed to provide adequate notice and an opportunity to comment during the rulemaking process, and could not cure that by later considering the merits of the petitioner's comments post-promulgation, through a petition to reconsider, where the issues involved were critical to the central issues involved in the rule.

Id.

at 1019.

EPA's failure to provide adequate notice and an opportunity to comment in violation of CAA section 307(d) was the critical underpinning for the court's determination that in that case consideration of the merits of the objections through a post-promulgation petition to reconsider was not an adequate substitute for providing the required procedural rights prior to promulgation. That, however, is not the case here. Petitioners are not claiming that the CRU e-mails or other documents show that EPA failed to provide adequate notice and an opportunity to comment because EPA failed to docket any documents or EPA docketed late any documents used to support EPA's final Endangerment Finding. Instead, petitioners are claiming that EPA should reopen the rulemaking and reconsider the Endangerment Finding based on new documents and arguments that petitioners bring to EPA, which they claim undermine the basis for EPA's Endangerment Finding.

There is no basis for treating the court's decision in

Kennecott

as precedent here, where there is no comparable procedural notice and comment violation by EPA. There is no reason to limit EPA's ability to consider the merits of the petitioners' objections through a post-promulgation petition to reconsider, whereas in this case there is no violation of a statutory right to notice and comment and EPA's consideration of the merits of the petitioners' objections is not being used as an improper substitute or cure for an EPA failure to provide adequate notice and an opportunity to comment prior to promulgation of the final rule. Unlike the situation in

Kennecott,

EPA's consideration of the petitions to reconsider is focused on whether the claimed new evidence and arguments warrant a reopening of a prior, properly noticed rulemaking. Absent a demonstration that the objections raised by petitioners provide substantial support for the argument that the regulation should be revised, such reopening is not warranted. Nothing in

Kennecott

holds otherwise.

Southeastern Legal Foundation, Inc. (SLF) inappropriately points to the docketing requirements under CAA section 307(d)(3) related to a proposed rule, SLF at 3-5. However, the documents SLF refers to are not EPA documents, were not part of the basis for EPA's proposal, and arose after the comment period, not prior to proposal. The provisions for a petition to reconsider under CAA section 307(d)(7), not the provisions of CAA section 307(d)(3), apply to the concerns raised by SLF with respect to the arguments and documents submitted to the agency after the end of the comment period, in the petitions to reconsider.

Appalachian Power Company et al.

EPA,

249 F.3d 1032 (D.C. Cir. 2001) clearly supports this view. In that case, petitioners presented comments to EPA requesting that EPA consider various materials concerning the issue of substantial contribution under section 126. Because EPA had already promulgated a rule that addressed the issue of significant contribution, EPA properly treated the request as a petition to reconsider the prior rule. EPA evaluated the evidence and its relevance to the section 126 rule and for a variety of reasons rejected it on the merits as a basis for reopening the rule. The court upheld EPA's decision, stating that “[g]iven the deferential standard employed in this context, the EPA's refusal to reopen and reconsider its significant contribution findings must be upheld.”

Id.

at 1060.

Part III of this Decision explains why EPA is denying the petitions with respect to the objections set forth in these petitions for reconsideration. With respect to some of these issues, the petitioners clearly have not met the procedural predicate for reconsideration. That is, the petitioners have not demonstrated that it was impracticable to raise these objections during the comment period, or that the grounds for these objections arose after the close of the comment period but within 60 days after publication of the final rule. As such, they do not meet the statutory criteria for administrative reconsideration under CAA section 307(d)(7)(B).

For all of the objections, whether or not the petitions might be considered to meet the procedural criterion for reconsideration, the petitioners' objections and arguments in terms of substance are not “of central relevance” to the outcome of the rulemaking. Thus, none of the objections meet the criteria for reconsideration under the CAA.

The Chamber of Commerce's petition was based on grounds that it claims arose after the time period for seeking judicial review of the underlying rulemaking. The Chamber argues that EPA should grant reconsideration in its discretion, even if it is not required to do so under section 307(d). The failure of the Chamber to file timely objections or to demonstrate that the objections it raises provide substantial support for the argument that the regulation should be revised are a fully adequate basis for EPA to deny the Chamber's petition. In any case, even if the petition were timely, EPA has considered the objections raised by the Chamber and is denying their petition as discussed in more detail herein.

As noted in Section I.B.4 of this Decision, EPA also received two requests to administratively stay the final Findings. Two petitioners requested an administrative stay under

CAA section 307(d)(7)(B), tied to the petitions to reconsider the findings, requesting that EPA stay the Findings for three months. Southeastern Legal Foundation at 8, Chamber of Commerce at 1. EPA has authority to issue a stay for up to 3 months if it grants a petition to reconsider under CAA section 307(d)(7)(B). As described below, EPA is denying the petitions to reconsider, hence there is no basis for issuance of an administrative stay under this provision.

One of the administrative stay requests was filed under section 705 of the Administrative Procedure Act (APA) as part of the petition for reconsideration relating to stationary source concerns, and requested a stay pending EPA's completion of its reconsideration of the final Findings. Chamber at 23-34. 5 U.S.C. 705 authorizes an agency to postpone the effective date of an agency action pending judicial review when the agency finds that justice so requires. In this case, the Endangerment Finding was effective as of January 14, 2010. The request for an administrative stay was submitted by petition dated March 15, 2010, after the Endangerment Finding was effective. Even if EPA believed that an administrative stay was warranted, which it does not, it is not clear whether EPA would have the authority under APA section 705 to stay an agency action that has already gone into effect. Postponing an effective date implies acting before the effective date occurs.

In any case, an administrative stay of the Endangerment Finding is not warranted. In response to the arguments raised by the Chamber, (1) the Chamber has not made a strong showing on the merits, for all of the reasons upon which EPA is denying the petitions to reconsider; (2) the Chamber's arguments concerning irreparable harm fail to adequately account for the proposed or recently issued Final Prevention of Significant Deterioration (PSD) and Title V Greenhouse Gas Tailoring Rule (75 FR 31518, 31579-84; June 3, 2010) (Final Tailoring Rule), and present general, unspecific, and unsupported arguments; (3) the Chamber's arguments that EPA's standards for emissions of GHGs from light-duty vehicles would have no important benefit because of the related NHTSA CAFE rule are rejected for the reasons discussed in Section IV.B of this Notice, and (4) the Chamber's arguments concerning the public interest, which repeat its prior arguments, are rejected for the same reasons.

III. Science Related Issues

A. General Summary of Petitioners' Arguments

The petitioners generally claim that the science underlying the Administrator's Endangerment Finding is flawed and/or that EPA did not follow an appropriate or robust process in evaluating the underlying science for purposes of making an endangerment finding for greenhouse gases. Many of the 10 petitions present similar arguments. Some of the petitioners' arguments were raised during the 60-day public comment period following the proposed Findings (74 FR 18886, April 24, 2009).

Many of the petitioners critique specific elements of the underlying science that support the Findings, primarily the HadCRUT temperature record showing increases in global surface temperatures. There are many elements of the underlying science that support the Administrator's Endangerment Finding that are not addressed by the petitioners. Petitioners assert that the global temperature record is so central to all greenhouse gas and climate change science that the problems with a global surface temperature record essentially mean all scientific knowledge linking greenhouse gases and climate change, and by extension all public health and welfare risks associated with human-induced climate change, must also be called into question. Petitioners also question the credibility of the IPCC and, by extension, EPA's use of IPCC AR4 as a significant reference document supporting the Findings.

The primary information provided by the petitioners to back their arguments are:

(1) A set of disclosed private e-mail communications among some scientists associated with the HadCRUT temperature record and associated with certain sections of IPCC AR4.

(2) A small number of factual mistakes and claimed factual mistakes and alleged unsupported statements in the voluminous, 2,927-page IPCC AR4.

(3) A limited number of new studies for EPA to consider.

EPA's responses to the petitioners' evidence, arguments, and claims are summarized in this section of this Decision and provided in fuller technical detail in the accompanying three-volume RTP document. More specifically, the petitioners' arguments can generally be grouped into three broad categories:

• Climate science and data issues, including (1) the validity of the reconstructed surface temperature record from the distant past and whether or not recent observations of global warming are unusual; (2) the validity of the more recent surface temperature record and whether recent temperature changes can be attributed to human emissions of greenhouse gases; (3) the validity of the HadCRUT surface temperature record of the Climatic Research Unit (CRU); (4) the validity of the recent surface temperature records constructed by the National Oceanographic and Atmospheric Administration (NOAA) and National Aeronautics and Space Administration (NASA); and (5) the implications of new studies not previously considered.

• Issues raised by EPA's use of IPCC reports, including: (1) Claims that recently found errors and claimed errors in IPCC AR4 undermine IPCC's credibility and therefore EPA's use of IPCC AR4 as a primary reference document; and (2) claims that IPCC has a policy agenda and is not an objective scientific body.

• Process and other issues, including claims that: (1) The USGCRP and the NRC are not separate and independent assessments from IPCC; (2) EPA's process to develop the scientific support for the Findings was inappropriate; (3) there are improper peer-review processes in the underlying scientific literature used by the major assessments; and (4) certain scientists did not adhere to UK and U.S. Freedom of Information Act Requests.

B. Summary of the Science Underlying the Administrator's Endangerment Finding in Light of the Petitioners' Claims

Before addressing the petitioners' general and specific assertions, this section briefly describes the major scientific conclusions and data that support the Administrator's Endangerment Finding that elevated atmospheric concentrations of the group of six key greenhouse gases are reasonably anticipated to endanger the public health and public welfare of current and future generations. As noted above, the petitioners do not take issue with the large body of scientific evidence. Rather, they focus most of their attention on questioning the validity of the global surface temperature record—specifically the HadCRUT temperature record, one of the three major global surface temperature records used by climate researchers—which show that temperatures are increasing. This section puts the global temperature record in the broader context of greenhouse gas and climate change

science, and demonstrates the limited scope of the petitioners' arguments.

There is a causal chain linking atmospheric concentrations of greenhouse gases to impacts and risks to public health and welfare. The elements of this causal chain are:

• What effects do greenhouse gases have on the environment and on climate in particular?

• Are human activities changing the amount of greenhouse gases in our atmosphere?

• What is the evidence indicating that average temperatures are increasing and that climate change is occurring, consistent with the direction one would expect from increasing greenhouse gases in our atmosphere?

• What is the evidence linking observed temperature changes and climate change to the anthropogenic increase in greenhouse gases?

• How are public health and welfare threatened by these changes to climate and the environment, now and in the future?

Each element of the causal chain is discussed below. Evidence related to each element is based on the underlying scientific assessments (e.g., IPCC and USGCRP) that EPA relied on to develop the TSD to support the Administrator's Endangerment Finding, and, where noted, is also based on the most recent scientific assessment, published in May 2010, of the NRC.

National Research Council (2010) Advancing the Science of Climate Change: America's Climate Choices, National Academies Press, Washington, DC.

1. What effects do greenhouse gases have on the environment and on climate in particular?

The physical effect of greenhouse gases on climate and the environment remains a basic scientific fact—greenhouse gases slow the loss of Earth's heat, which would otherwise escape to space. Much like a blanket keeps a person warm by preventing heat loss, greenhouse gases blanket the planet and warm the Earth by trapping in heat that would otherwise escape to space. This is the Earth's natural greenhouse effect. An increase in the amount of greenhouse gases in our atmosphere intensifies the natural greenhouse effect and thus exerts a warming effect on the global climate. These are well-established physical properties of greenhouse gases. The six greenhouse gases grouped together in the Administrator's Endangerment Finding are long-lived in the atmosphere and, once emitted, can remain in the atmosphere for decades to centuries. Carbon dioxide has other non-climate effects as well. Increases in atmospheric carbon dioxide concentrations can affect oceanic acidity and the growth rates of crops, weeds, and trees. Petitioners have not presented information challenging the basic physical properties of how the six greenhouse gases affect the climate and the environment.

2. How are human activities changing the amount of greenhouse gases in our atmosphere?

It is a well-documented and straightforward observation that levels of carbon dioxide and other greenhouse gases are increasing in our atmosphere. The six key greenhouse gases included in the Administrator's Findings are at essentially unprecedented levels compared to the recent and distant past. Their concentrations are climbing, and this is projected to continue well into this century. The two most important directly emitted greenhouse gases, carbon dioxide and methane, are well above the natural range of atmospheric concentrations compared to at least the last 650,000 years (see TSD EPA-HQ-OAR-2009-0171-11645). The most recent report of the NRC states that carbon dioxide levels are now at 388 parts per million and increasing by almost two parts per million per year.

The fact that greenhouse concentrations are now at such high levels is absolutely central to the Administrator's Endangerment Finding. Without such a large and ever-increasing buildup of atmospheric levels of greenhouse gases there would be less concern about the potential future warming caused by human activities. Greenhouse gases are at such high levels in our atmosphere and continue to climb because human activities are adding greenhouse gases to the atmosphere in larger quantities and more quickly than the environment can handle. Our annual emissions from fossil fuel combustion, deforestation, and other sources are overwhelming the natural removal systems in the ocean, atmosphere, and terrestrial biosphere (e.g., trees and other vegetation).

Furthermore, human activities are unambiguously the driver of the increase in atmospheric levels of greenhouse gases. The EPA TSD states: “The global atmospheric CO

concentration has increased about 38% from pre-industrial levels to 2009, and almost all of the increase is due to anthropogenic emissions.” This is supported by the most recent NRC report, which states that, “We know that this increase is largely the result of human activities because the chemical signature of excess CO

in the atmosphere can be linked to the composition of the CO

emissions from fossil fuel burning. Moreover, analyses of bubbles trapped in ice cores from Greenland and Antarctica reveal that atmospheric CO

levels have been rising steadily since the start of the Industrial Revolution.” Petitioners do not provide any evidence that cause EPA to question this scientific conclusion.

The scientific literature is clear that the heating effect caused by the buildup of greenhouse gases is warming the climate system. As summarized in the TSD:

• The global average net effect of the increase in atmospheric GHG concentrations, plus other human activities (e.g., land-use change and aerosol emissions), on the global energy balance since 1750 has been one of warming. This total net heating effect, referred to as forcing, is estimated to be +1.6 (+0.6 to +2.4) watts per square meter (W/m

), with much of the range surrounding this estimate due to uncertainties about the cooling and warming effects of aerosols.

• Warming of the climate system is unequivocal, as is now evident from observations of increases in global average air and ocean temperatures, widespread melting of snow and ice, and rising global average sea level. Global mean surface temperatures have risen by 1.3 ± 0.32 °F (0.74 °C ± 0.18 °C) over the last 100 years. Eight of the 10 warmest years on record have occurred since 2001. Global mean surface temperature was higher during the last few decades of the 20th century than during any comparable period during the preceding four centuries.

• U.S. temperatures also warmed during the 20th and into the 21st century; temperatures are now approximately 1.3 °F (0.7 °C) warmer than at the start of the 20th century, with an increased rate of warming over the past 30 years. Both the IPCC and the USGCRP

reports attributed recent North American warming to elevated GHG concentrations. In the U.S. Climate Change Science Program (CCSP) (2008)

report, the authors find that for

North America, “more than half of this warming [for the period 1951-2006] is likely the result of human-caused GHG forcing of climate change.”

USGCRP now encompasses the former Climate Change Science Program (CCSP) under the previous Administration.

CCSP (2008). Reanalysis of Historical Climate Data for Key Atmospheric Features: Implications for Attribution of Causes of Observed Change. A Report

by the U.S. Climate Change Science Program and the Subcommittee on Global Change Research [Randall Dole, Martin Hoerling, and Siegfried Schubert (eds.)]. Asheville, NC: National Oceanic and Atmospheric Administration, National Climatic Data Center. 156 pp.

• Widespread changes in extreme temperatures have been observed in the last 50 years across all world regions, including the United States. Cold days, cold nights, and frost have become less frequent, while hot days, hot nights, and heat waves have become more frequent.

• There is strong evidence that global sea level gradually rose in the 20th century and is currently rising at an increased rate.

• Satellite data since 1979 show that annual average Arctic sea ice extent has shrunk by 4.1% per decade.

• Observational evidence from all continents and most oceans shows that many natural systems are being affected by regional climate change, particularly temperature increases.

• Observations show that climate change is currently affecting U.S. physical and biological systems in significant ways.

• Ocean CO

uptake has lowered the average ocean pH (increased acidity) level by approximately 0.1 since 1750.

These conclusions are consistent with, or strengthened by, the most recent NRC report which states the following: “Earth is warming. Detailed observations of surface temperature assembled and analyzed by several different research groups show that the planet's average surface temperature was 1.4 °F (0.8 °C) warmer during the first decade of the 21st century than during the first decade of the 20th century, with the most pronounced warming over the last three decades. These data are corroborated by a variety of independent observations that indicate warming in other parts of the Earth system, including the cryosphere (snow and ice covered regions), the lower atmosphere, and the oceans.”

These multiple lines of evidence highlight a number of things. First, there is well-documented evidence that the buildup of greenhouse gases in our atmosphere is exerting, as expected, a significant heating effect called radiative forcing. This is not to be confused with temperature change or the temperature data that is the subject of many of the petitions. This heating effect or radiative forcing refers to a change in the energy balance of the planet, and is thus the driver of temperature change.

The magnitude of this heating effect caused by the buildup in atmospheric greenhouse gases has been quantified in the scientific literature. The petitioners do not challenge these estimates and do not challenge the fact that the observed buildup of greenhouse gases is having a clear and quantifiable heating effect on the planet. This is a fundamental pillar of climate change science, and is a fundamental piece of supporting evidence for the Administrator's Endangerment Finding.

Second, the underlying science indicates that there is significant and unambiguous warming for the Earth and for North America. This is the first place along the causal chain where the petitioners question the science. Many petitioners question the validity of the global temperature evidence by pointing to the CRU e-mails and their impact on the scientific assessment reports used by EPA. This particular critique is addressed below and in fuller detail in Volume 1 of the RTP document.

Third, the evidence of climate change caused by human activities goes beyond average increases in global and continental temperatures. There are well-documented increases in sea level, declines in sea ice, and changes to physical and biological systems, all primarily driven by, and therefore showing further evidence of, increases in average temperatures. These changes are documented by datasets other than temperature datasets, and bear no relation to the particular CRU temperature dataset that is the primary focus of many of the petitioners.

Similarly, the observation that elevated levels of carbon dioxide are increasing the acidity of the world's oceans is direct evidence of a large-scale and significant environmental effect that does not depend on any evidence from a temperature dataset. This particular effect was considered supporting evidence by the Administrator in the Endangerment Finding. This documented effect is not challenged by any of the petitioners.

4. What is the evidence linking observed temperature changes and climate change to the anthropogenic increase in greenhouse gases?

The underlying science has clearly attributed the observed warming to the buildup of greenhouse gases in our atmosphere. Summarized here is the underlying science that shows that increases in average global and continental temperatures, as well as other climatic changes, can confidently be attributed to the increases in greenhouse gas emissions from human activities. The extent to which observed warming can be attributed to the human-induced buildup of greenhouse gases in the atmosphere is the second area of the causal chain where some petitioners question the science.

IPCC statements on the linkage between greenhouse gases and temperatures have strengthened since the organization's early assessments (Solomon et al., 2007).

The IPCC's

First Assessment Report

in 1990 contained little observational evidence of a detectable anthropogenic influence on climate (IPCC, 1990).

In its

Second Assessment Report

in 1995, the IPCC stated that the balance of evidence suggests a discernible human influence on the climate of the 20th century (IPCC, 1996).

The

Third Assessment Report

in 2001 concluded that most of the observed warming over the last 50 years is likely to have been due to the increase in greenhouse gas concentrations (IPCC, 2001b).

The conclusion in IPCC's 2007

Fourth Assessment Report

(2007b)

is the strongest yet: “Most of the observed increase in global average temperatures since the mid-20th century is very likely

due to the observed increase in anthropogenic GHG concentrations.”

Solomon, S., D. Qin, M. Manning, R.B. Alley, T. Berntsen, N.L. Bindoff, Z. Chen, A. Chidthaisong, J.M. Gregory, G.C. Hegerl, M. Heimann, B. Hewitson, B.J. Hoskins, F. Joos, J. Jouzel, V. Kattsov, U. Lohmann, T. Matsuno, M. Molina, N. Nicholls, J. Overpeck, G. Raga, V. Ramaswamy, J. Ren, M. Rusticucci, R. Somerville, T.F. Stocker, P. Whetton, R.A. Wood and D. Wratt (2007). Technical Summary. In: Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change [Solomon, S., D. Qin, M. Manning, Z. Chen, M. Marquis, K.B. Averyt, M. Tignor, and H.L. Miller (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA, 996 pp.

IPCC (1990). First Assessment Report: Climate Change 1990. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA.

IPCC (1996). Climate Change 1995: The Science of Climate Change. Intergovernmental Panel on Climate Change [J.T. Houghton, L.G. Meira Filho, B.A. Callander, N. Harris, A. Kattenberg, and K. Maskell (eds)]. Cambridge University Press. Cambridge, United Kingdom.

IPCC (2001b). Summary for Policymakers. In. Climate Change 2001: The Scientific Basis. Contribution of Working Group I to the Third Assessment Report of the Intergovernmental Panel on Climate Change [J.T. Houghton et al. (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA.

IPCC (2007b). Climate Change 2007: Synthesis Report. Contribution of Working Groups I, II and III to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change [Core Writing Team, Pachauri, R.K and Reisinger, A. (eds.)]. IPCC, Geneva, Switzerland, 104 pp.

According to IPCC terminology, “very likely” conveys a 90 to 99% probability of occurrence. See Box 1.2 of the TSD for a full description of IPCC's uncertainty terms.

The strength of this statement reflects our current, much better understanding

of all the factors, not just greenhouse gases, that influence temperature fluctuations and other climatic changes. On this point, EPA's TSD (citing Hegerl

et al.,

2007)

listed the major scientific advances between the Third and Fourth Assessment Reports of the IPCC that led to this increased confidence in the ability to attribute observed temperature and other climate changes to anthropogenic greenhouse gases:

Hegerl, G.C.,

et al.

(2007). Understanding and Attributing Climate Change. In: Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change [Solomon, S., D. Qin, M. Manning, Z. Chen, M. Marquis, K.B. Averyt, M. Tignor, and H.L. Miller (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA.

• An expanded and improved range of observations allowing attribution of warming to be more fully addressed jointly with other changes in the climate system.

• Improvements in the simulation of many aspects of present mean climate and its variability on seasonal to inter-decadal time scales.

• More detailed representations of processes related to aerosol and other forcings (i.e., heating and cooling effects) in models.

• Simulations of 20th-century climate change that use many more models and much more complete anthropogenic and natural forcings.

• Multi-model ensembles that increase confidence in attribution results by providing an improved representation of model uncertainty.

Climate model simulations suggest that natural heating factors alone cannot explain the observed warming for the entire globe, the global land, or the global ocean. The observed warming can only be reproduced with models that contain both natural and anthropogenic heating and cooling influences.

EPA's TSD, based on the underlying assessment literature, states that if the additional heating effect of elevated levels of greenhouse gases were the only external influence on the global climate, this likely would have resulted in warming greater than observed. This statement is made because our understanding of the climate system is sophisticated enough to consider and model multiple and simultaneous influences on the global climate. For example, there are known and quantifiable cooling effects from human emissions of aerosols and natural forcings (e.g., volcanic eruptions and solar variability) that have offset some of the greenhouse gas-induced warming during the past half century.

The sophistication of climate models that examine the influence of human emissions of greenhouse gases has increased. Confidence in these models comes from their foundation in accepted physical principles and from their ability to reproduce observed features of current climate and past climate changes (IPCC, 2007a).

One petitioner questions the reliability of the models by pointing to certain CRU e-mails. Questions regarding the reliability of climate models are addressed in Volume 4 of the RTC document and in Volume 1 of the RTP document.

IPCC (2007a) Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change. [Solomon, S., D. Qin, M. Manning, Z. Chen, M. Marquis, K.B. Averyt, M. Tignor, and H.L. Miller (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA.

Furthermore, warming of the climate system has been detected in changes of surface and atmospheric temperatures, in the upper several hundred meters of the ocean (as evident by the observed increase in ocean heat content), and in contributions to sea level rise. The scientific assessments have established human contributions to all of these changes.

Not only has an anthropogenic warming signal been detected for the surface temperatures, but evidence has also accumulated of an anthropogenic influence throughout different layers of the atmosphere. Some petitioners have raised one potential inconsistency between observed warming and modeled warming higher in the atmosphere over the tropics. Karl

et al.

(2009)

state that when uncertainties in models and observations are properly accounted for, newer observational datasets are in agreement with climate model results. A detailed discussion of this issue is contained in Volume 1, section 1.2 of the RTP document.

Karl, T., J. Melillo, and T. Peterson (Eds.) (2009) Global Climate Change Impacts in the United States. Cambridge University Press, Cambridge, United Kingdom.

Lastly, evidence from climates in the geologic past, going back millions of years, also supports the conclusion that elevated levels of greenhouse gases in the atmosphere are expected to lead to warmer climates. Measurements show that climates from the geologic past have been both warmer and colder than present, and that warmer periods have generally coincided with high atmospheric carbon dioxide levels. Analyses of these paleoclimate data have increased confidence in the role of external influences on climate. Climate models for predicting future climate have been used to reproduce key features of past climates using conditions and radiative forcing for those periods.

Here too, these conclusions are reinforced by the most recent NRC report, which states:

“Global warming can be attributed to human activities. Many lines of evidence support the conclusion that most of the observed warming since the start of the 20th century, and especially the last several decades, can be attributed to human activities, including the following:

• Earth's surface temperature has clearly risen over the past 100 years, at the same time that human activities have resulted in sharp increases in CO

and other GHGs.

• Both the physics of the greenhouse effect and more detailed calculations dictate that increases in atmospheric GHGs should lead to warming of Earth's surface and lower atmosphere.

• The vertical pattern of observed warming—with warming in the bottommost layer of the atmosphere and cooling immediately above—is consistent with warming caused by GHG increases, and inconsistent with other possible causes.

• Detailed simulations with state-of-the-art computer-based models of the climate system are able to reproduce the observed warming tend and patterns only when human-induced GHG emissions are included.

Based on these and other lines of evidence, the Panel on Advancing the Science of Climate Change—along with an overwhelming majority of scientists (Rosenberg

et al.,

2010)—conclude that much of the observed warming since the start of the 20th century, and most of the warming over the last several decades, can be attributed to human activities” [NRC at 29].

The clear conclusion from all of this evidence is that the human-induced buildup of greenhouse gases in the atmosphere is primarily responsible for most of the observed warming and other climate changes occurring now. The information petitioners present to challenge this part of the scientific record is clearly inadequate.

• Petitioners provide no credible evidence to question the clear observation that greenhouse gases are increasing in our atmosphere to significant levels.

• The petitioners provide no information to question the quantified radiative forcing (heating effect) caused by this greenhouse gas buildup.

• Petitioners' objections about paleoclimate temperature reconstructions focus on one type of reconstruction (tree ring analysis). The objections, addressed in Volume 1 of the RTP document, do not withstand scrutiny, nor do they undermine our confidence in the conclusions of the studies. These conclusions, and the accompanying limitations and uncertainties, have been properly characterized in the assessment reports

and the Endangerment Finding. Petitioners do not contest or address the variety of other aspects of paleoclimate research supporting the attribution of recent warming to anthropogenic greenhouse gases.

• With respect to the variety of evidence on observed temperature change, the petitioners focus their criticism on the validity of one of three global surface temperature records, the HadCRUT temperature record. Petitioners' objections are addressed in detail below and in Volume 1 of the RTP document, as are the petitioners' related criticisms of the NOAA and NASA temperature datasets. Their objections do not withstand scrutiny, nor do they reduce our confidence in these temperature records, which have been properly characterized in the assessment reports and the Endangerment Finding. In addition, the petitioners ignore and do not address the clear information and observations showing that other elements of the climate system are undergoing changes consistent with these average temperature increases (e.g., ocean heating, sea level rise, Arctic ice loss). Petitioners do not show that these observations are in error or are the result of some other, unidentified mechanism.

• Petitioners focus their criticism on a possible discrepancy between model predictions and the vertical temperature structure of the atmosphere in the tropics; this criticism is not substantively supported, as discussed below and in Volume 1 of the RTP document.

• The petitioners do not attempt to provide an alternative explanation of the compellingly strong match between the observed magnitude and pattern of warming and the modeled simulations, which include all known factors, including the greenhouse gas buildup, the offsetting cooling influence of aerosols, and variability in solar output.

• Petitioners' arguments that a possible slowdown in the rate of warming over the last 10 years should weaken confidence in the fact that human emissions of greenhouse gases are the primary driver of recent warming are not valid. EPA addresses this issue more fully below and in Volume 1 of the RTP document.

5. How are public health and welfare threatened by these changes to climate and the environment, now and in the future?

The TSD summarizes a number of conclusions from the underlying science on this issue. In addition to documenting many of the key observed changes to atmospheric composition and climate, such as those outlined above, the TSD summarizes key findings about projected increases in greenhouse gas emissions and the future climate change associated with these future scenarios:

• Most future scenarios that assume no explicit greenhouse gas mitigation actions (beyond those already enacted) project increasing global greenhouse gas emissions over the century, with climbing greenhouse gas concentrations.

• Future warming over the course of the 21st century, even under scenarios of low-emission growth, is very likely to be greater than observed warming over the past century.

• All of the United States is very likely to warm during this century, and most areas of the United States are expected to warm by more than the global average.

• It is very likely that heat waves will become more intense, more frequent, and longer-lasting in a future warm climate, whereas cold episodes are projected to decrease significantly.

• Increases in the amount of precipitation are very likely in higher latitudes, while decreases are likely in most subtropical latitudes and in the southwestern United States, continuing observed patterns.

• Intensity of precipitation events is projected to increase in the United States and other regions of the world.

• It is likely that hurricanes will become more intense, with stronger peak winds and more heavy precipitation associated with ongoing increases of tropical sea surface temperatures. Frequency changes in hurricanes are currently too uncertain for confident projections.

• By the end of the century, global average sea level is projected by the IPCC to rise between 7.1 and 23 inches (18 and 59 centimeter [cm]), relative to around 1990, in the absence of increased dynamic ice sheet loss.

• Sea ice extent is projected to shrink in the Arctic under all IPCC emission scenarios.

The validity of these future climate change projections is not addressed by the petitioners, although some of the petitioners do call into question the climate models that are used to conduct these climate change projections. The petitioners claim that some of the models must be calibrated with the current temperature record, which in turn they assert appears to be flawed. EPA addresses this faulty critique of the models in Volume 1, section 1.2.3 of the RTP document, and had previously addressed similar critiques of climate models in Volume 4 of the RTC document.

It is important to note that none of the petitioners question the conclusion that atmospheric levels of greenhouse gases are expected to continue climbing for the foreseeable future, given the long-lived physical properties of the greenhouse gases themselves and the plausible pathways of human-emitting activities over the next few decades. Climate models aside, it is difficult to imagine a world where the heating effect of climbing greenhouse gas concentrations does not increase for the foreseeable future.

With regard to the impacts and risks to public health and welfare, the TSD and the Administrator's Findings stated the following:

• Severe heat waves are projected to intensify in magnitude and duration over the portions of the United States where these events already occur, with potential increases in mortality and morbidity, especially among the elderly, young, and frail.

• Some reduction in the risk of death related to extreme cold is expected. It is not clear whether reduced mortality from cold will be greater or less than increased heat-related mortality in the United States due to climate change. In addition, the latest USGCRP report refers to a study that analyzed daily mortality and weather data in 50 U.S. cities from 1989 to 2000 and found that, on average, cold snaps in the United States increased death rates by 1.6 percent, while heat waves triggered a 5.7 percent increase in death rates. The study concludes that increases in heat-related mortality due to global warming in the United States are unlikely to be compensated for by decreases in cold-related mortality.

• Increases in regional ozone pollution relative to ozone levels without climate change are expected due to higher temperatures and weaker circulation in the United States and other world cities relative to air quality levels without climate change.

• CCSP concludes that, with increased CO

and temperature, the life cycle of grain and oilseed crops will likely progress more rapidly. But, as temperature rises, these crops will increasingly begin to experience failure, especially if climate variability increases and precipitation lessens or becomes more variable.

• Higher temperatures will very likely reduce livestock production during the summer season in some areas, but these losses will very likely be partially offset by warmer temperatures during the winter season.

• Cold-water fisheries will likely be negatively affected; warm-water fisheries will generally benefit; and the

results for cool-water fisheries will be mixed, with gains in the northern and losses in the southern portions of ranges.

• Climate change has very likely increased the size and number of forest fires, insect outbreaks, and tree mortality in the interior West, the Southwest, and Alaska, and will continue to do so.

• Coastal communities and habitats will be increasingly stressed by climate change impacts interacting with development and pollution.

• Climate change will likely further constrain already overallocated water resources in some regions of the United States, increasing competition among agricultural, municipal, industrial, and ecological uses.

• Higher water temperatures, increased precipitation intensity, and longer periods of low flows will exacerbate many forms of water pollution, potentially making attainment of water quality goals more difficult.

• Ocean acidification is projected to continue, resulting in the reduced biological production of marine calcifiers, including corals.

• Climate change is likely to affect U.S. energy use and energy production and physical and institutional infrastructures.

Furthermore, the most recent NRC report from 2010 states that: “Global warming is closely associated with a broad spectrum of other climate changes, such as increases in the frequency of intense rainfall, decreases in snow cover and sea ice, more and increasingly intense heat waves, rising sea levels, and widespread ocean acidification. Individually and collectively, and in combination with the effects of other human activities, these changes pose risks for a wide range of human and environmental systems, including freshwater resources, the coastal environment, ecosystems, agriculture, fisheries, human health, and national security, among others.”

The petitioners have not raised any objections to EPA's analysis and judgments concerning these risks and impacts to public health and welfare, which were the foundation of the Administrator's Endangerment Finding.

C. Review of the Administrator's Findings

Throughout this Decision, EPA explains why the petitioners' arguments and information fail to show that the scientific underpinnings of the Endangerment Finding are flawed. EPA remains convinced that the underlying science is robust, and that the Administrator appropriately interpreted the science to make the Endangerment Finding. This section summarizes the Administrator's December 2009 rationale and judgment based on the underlying science.

The Administrator exercised her judgment under CAA section 202(a) by evaluating what the body of scientific evidence indicates with respect to how greenhouse gases affect the climate, and the degree of scientific consensus about the appropriate conclusions to draw from this evidence. Based on this consideration, the Administrator proposed and took comment on her preliminary judgment of endangerment to public health and welfare. The Administrator found the case to be compelling that greenhouse gas air pollution endangers both public health and welfare within the United States. The underlying science that EPA relied on included careful qualifications and characterizations about the degree of certainty regarding the scientific conclusions that were germane to the Administrator's Findings. The Administrator's reasoning and decision-making process to reach the Findings make clear that there was full acknowledgement that certain elements of the science are known with virtual certainty and others are currently more uncertain.

A robust and comprehensive opportunity for comment allowed any and all objections regarding her judgment to be raised. After carefully reviewing the comments, the Administrator confirmed her judgment on endangerment and provided responses to the scientific, legal, and policy issues raised by commenters. The final rule explains in detail the basis for the Administrator's Endangerment Finding. Key elements of the Administrator's justification and decision process are summarized in the following 10 paragraphs from the December 15, 2009 Findings (74 FR 66523-24).

“As described in Section II of these Findings, the endangerment test under CAA section 202(a) does not require the Administrator to identify a bright line, quantitative threshold above which a positive endangerment finding can be made. The statutory language explicitly calls upon the Administrator to use her judgment. This section describes the general approach used by the Administrator in reaching the judgment that a positive endangerment finding should be made, as well as the specific rationale for finding that the greenhouse gas air pollution may reasonably be anticipated to endanger both public health and welfare.

First, the Administrator finds the scientific evidence linking human emissions and resulting elevated atmospheric concentrations of the six well-mixed greenhouse gases to observed global and regional temperature increases and other climate changes to be sufficiently robust and compelling. This evidence is briefly explained in more detail in Section V of these Findings. The Administrator recognizes that the climate change associated with elevated atmospheric concentrations of carbon dioxide and the other well-mixed greenhouse gases have the potential to affect essentially every aspect of human health, society, and the natural environment.

The Administrator is therefore not limiting her consideration of potential risks and impacts associated with human emissions of greenhouse gases to any one particular element of human health, sector of the economy, region of the country, or to any one particular aspect of the natural environment. Rather, the Administrator is basing her finding on the total weight of scientific evidence, and what the science has to say regarding the nature and potential magnitude of the risks and impacts across all climate-sensitive elements of public health and welfare, now and projected out into the foreseeable future. The Administrator has considered the state of the science on how human emissions and the resulting elevated atmospheric concentrations of well-mixed greenhouse gases may affect each of the major risk categories, i.e., those that are described in the TSD, which include human health, air quality, food production and agriculture, forestry, water resources, sea level rise and coastal areas, the energy sector, infrastructure and settlements, and ecosystems and wildlife. The Administrator understands that the nature and potential severity of impacts can vary across these different elements of public health and welfare, and that they can vary by region, as well as over time.

The Administrator is therefore aware that, because human-induced climate change has the potential to be far-reaching and multi-dimensional, not all risks and potential impacts can be characterized with a uniform level of quantification or understanding, nor can they be characterized with uniform metrics. Given this variety in not only the nature and potential magnitude of risks and impacts, but also in our ability to characterize, quantify and project into the future such impacts, the Administrator must use her judgment to weigh the threat in each of the risk categories, weigh the potential benefits where relevant, and ultimately judge whether these risks and benefits, when viewed in total, are judged to be endangerment to public health and/or welfare.

This has a number of implications for the Administrator's approach in assessing the nature and magnitude of risk and impacts across each of the risk categories. First, the Administrator has not established a specific threshold metric for each category of risk and impacts. Also, the Administrator is not necessarily placing the greatest weight on those risks and impacts, which have been the subject of the most study or quantification.

Part of the variation in risks and impacts is the fact that climbing atmospheric

concentrations of greenhouse gases and associated temperature increases can bring about some potential benefits to public health and welfare in addition to adverse risks. The current understanding of any potential benefits associated with human-induced climate change is described in the TSD and is taken into consideration here. The potential for both adverse and beneficial effects are considered, as well as the relative magnitude of such effects, to the extent that the relative magnitudes can be quantified or characterized. Furthermore, given the multiple ways in which the buildup of atmospheric greenhouse gases can cause effects (e.g., via elevated carbon dioxide concentrations, via temperature increases, via precipitation increases, via sea level rise, and via changes in extreme events), these multiple pathways are considered. For example, elevated carbon dioxide concentrations may be beneficial to crop yields, but changes in temperature and precipitation may be adverse and must also be considered. Likewise, modest temperature increases may have some public health benefits as well as harms, and other pathways such as changes in air quality and extreme events must also be considered.

The Administrator has balanced and weighed the varying risks and effects for each sector. She has judged whether there is a pattern across the sector that supports or does not support an endangerment finding, and if so, whether the support is of more or less weight. In cases where there is both a potential for benefits and risks of harm, the Administrator has balanced these factors by determining whether there appears to be any directional trend in the overall evidence that would support placing more weight on one than the other, taking into consideration all that is known about the likelihood of the various risks and effects and their seriousness. In all of these cases, the judgment is largely qualitative in nature, and is not reducible to precise metrics or quantification.

Regarding the timeframe for the endangerment test, it is the Administrator's view that both current and future conditions must be considered. The Administrator is thus taking the view that the endangerment period of analysis extend from the current time to the next several decades, and in some cases to the end of this century. This consideration is also consistent with the timeframes used in the underlying scientific assessments. The future timeframe under consideration is consistent with the atmospheric lifetime and climate effects of the six well-mixed greenhouse gases, and also with our ability to make reasonable and plausible projections of future conditions.

The Administrator acknowledges that some aspects of climate change science and the projected impacts are more certain than others. Our state of knowledge is strongest for recently observed, large-scale changes. Uncertainty tends to increase in characterizing changes at smaller (regional) scales relative to large (global) scales. Uncertainty also increases as the temporal scales move away from present, either backward, but more importantly, forward in time. Nonetheless, the current state of knowledge of observed and past climate changes and their causes enables projections of plausible future changes under different scenarios of anthropogenic forcing for a range of spatial and temporal scales.

In some cases, where the level of sensitivity to climate of a particular sector has been extensively studied, future impacts can be quantified whereas in other instances only a qualitative description of a directional change, if that, may be possible. The inherent uncertainty in the direction, magnitude, and/or rate of certain future climate change impacts opens up the possibility that some changes could be more or less severe than expected, and the possibility of unanticipated outcomes. In some cases, low probability, high impact outcomes (i.e., known unknowns) are possibilities but cannot be explicitly assessed.”

The Findings show that the Administrator took a measured, balanced and systematic approach in judging the body of scientific evidence for the Endangerment Finding. The Administrator did not take a narrow view of the science, nor consider only those pieces of evidence that would support a positive endangerment finding.

In taking this approach, the Administrator determined that the body of scientific evidence compellingly supports a positive endangerment finding. The major assessments by the USGCRP, IPCC, and the NRC (published before 2010) served as the primary scientific basis supporting the Administrator's endangerment finding. The Administrator reached her determination by considering both observed and projected effects of greenhouse gases in the atmosphere, their effect on climate, and the public health and welfare risks and impacts associated with such climate change. The Administrator's assessment focused on public health and public welfare impacts within the United States. She also examined the evidence with respect to impacts in other world regions, and she concluded that these impacts strengthen the case for endangerment to public health and welfare because impacts in other world regions can in turn adversely affect the United States.

The Administrator considered how elevated concentrations of the well-mixed greenhouse gases and associated climate change affect public health by evaluating the risks associated with changes in air quality, increases in temperatures, changes in extreme weather events, increases in food- and water-borne pathogens, and changes in aeroallergens. The Administrator placed weight on the fact that certain groups, including children, the elderly, and the poor, are most vulnerable to these climate-related health effects.

The Administrator considered how elevated concentrations of the well-mixed greenhouse gases and associated climate change affect public welfare by evaluating numerous and far-ranging risks to food production and agriculture, forestry, water resources, sea level rise and coastal areas, energy, infrastructure, and settlements, and ecosystems and wildlife. For each of these sectors, the evidence provides support for a finding of endangerment to public welfare. The evidence concerning adverse impacts in the areas of water resources and sea level rise and coastal areas provides the clearest and strongest support for an endangerment finding, both for current and future generations. Strong support is also found in the evidence concerning infrastructure and settlements, as well as ecosystems and wildlife. Across the sectors, the potential serious adverse impacts of extreme events, such as wildfires, flooding, drought, and extreme weather conditions, provide strong support for such a finding.

The petitioners have not provided information that would lead EPA to believe that the Administrator's approach, briefly summarized here and explained in full in the December 2009 Findings, was flawed, should have been carried out differently, or should have led to a different conclusion.

D. General Response to the Petitioners' Scientific Arguments in Light of the Full Body of Scientific Evidence

EPA's overarching conclusion is that there is no material or reliable basis to question the validity and credibility of the body of science underlying the Administrator's Endangerment Finding or the Administrator's decision process articulated in the Findings themselves. The large body of scientific evidence and the Administrator's conclusions drawn from this evidence, including the appropriate characterizations as to the degrees of certainty and uncertainty in the underlying science, has not been changed by the arguments presented by the petitioners. While the petitioners largely rely on making broad assertions about the science based on private communications, EPA's focus is on the actual science itself, and the petitioners have not presented a valid basis supporting the view that the credibility or reliability of either the science or the scientific conclusions that petitioners contest have been undermined or changed in any material way.

The petitioners present very little scientific evidence or scientific arguments to support their views. As demonstrated above, they do not rely on an in-depth and comprehensive analysis of the science and make arguments on

that basis. Instead they largely rely on a small number of statements from the CRU e-mails in which certain scientists expressed various thoughts and feelings, such as frustration and disrespect for other scientists, along with strong views on scientific issues and what constitutes good science. From this evidence, the petitioners conclude that the scientists acted together to distort the review and presentation of the body of science, and presented false, inaccurate, or misleading conclusions about what the body of scientific studies tells us about various aspects of climate change.

Petitioners do not argue their case by marshalling and synthesizing the breadth of the body of scientific evidence and demonstrating why it leads to a different conclusion than that presented in the underlying science supporting the Findings. Instead, they largely argue that the state of mind of these scientists and their private remarks must lead to the conclusions drawn by the petitioners. They also conclude, based on a selective reading of the CRU e-mails, that the state of the science must be much more uncertain than how it is characterized in the underlying assessment reports used by EPA and the Endangerment Finding. Other than the conduct of sending e-mails that evidence strong emotions or unprofessional language, the petitioners present almost no evidence of any actual conduct by the scientists that support their conclusion that the science was assessed inaccurately. Most of the conduct that is identified, such as statements about the professional challenges of working as an IPCC lead author or the discussion with a journal editor to delay the paper publication (but not the online publication) of a study, is of no relevance to the evaluation of the science involved in the assessment reports and the EPA rulemaking.

Petitioners' claims of distortion of data, withholding of temperature data, or abuses in data analysis also do not withstand scrutiny. These issues are addressed in fuller detail in volumes 1 and 3 of the RTP document. In addition, some of these issues were raised and addressed by EPA during the public comment period, and thus fail to meet the test in CAA 307(d). Petitioners have shown no evidence that the HadCRUT temperature record based on the underlying raw temperature data was flawed in any way, or that CRU's lack of possession of a small portion of the raw temperature data impedes the ability of other researchers to check the publically available data, or that it changes the scientific validity of the analyses performed by CRU. The HadCRUT temperature record remains consistent with all of the other evidence of warming, including other surface temperature analyses as well as other evidence of warming, such as satellite data, ocean temperature data, and physical and biological evidence of the effects of warming.

The petitioners ask EPA to reject the comprehensive and well-documented views reflecting a synthesis of the body of scientific evidence produced by the U.S. and the world's climate science community, and instead accept assertions and three profound leaps in logic, based on a very limited discussion of the underlying science. The first leap is that petitioners' objections to the HadCRUT surface temperature record and objections to reconstructions of past global temperatures are correct, and that as a result all other elements of greenhouse gas and climate change science indicating temperatures are increasing and that anthropogenic greenhouse gases are the primary driver should be called into question. The second leap is that some errors found in the IPCC AR4—errors that are both minor and tangential to EPA's Endangerment Finding—mean that any and all information from that report should be called into question. The third is that any other assessment report that relies on or references the IPCC AR4 in any way is also suspect and cannot serve as a foundation for the Endangerment Finding. EPA's review, discussed in the following sections and in fuller detail in the three volumes of the RTP document, plus the latest conclusions of the May 2010 NRC scientific assessment, lead us to the firm conclusion that the petitioners' specific arguments and broad claims must be rejected for their lack of supporting evidence and absence of comprehensive and clear scientific reasoning.

As stated in one of the findings of the Independent Climate Change E-mails Review, “In particular, we did not find any evidence of behaviour that might undermine the conclusions of the IPCC assessments.” EPA's review and analysis leads to this same conclusion.

E. Specific Responses to the Claims and Arguments Raised by Petitioners

EPA's responses to the petitioners' specific claims and arguments are summarized here, and provided in more detail in the RTP document. The more general conclusions provided in this Decision, articulated above, are based on EPA's detailed analysis of and responses to the petitioners' issues contained in the RTP document. As stated previously, the science-based objections raised by petitioners fall into three categories: Climate science and data issues; issues raised by EPA's use of IPCC AR4; and process issues. This section and the three volumes of the RTP document are organized around these three categories.

1. Climate Science and Data Issues Raised by the Petitioners

The climate science and data issues raised by the petitioners include (a) the validity of the temperature record from the distant past and whether or not recent observations of global warming are unusual; (b) the validity of the more recent surface temperature record; (c) the validity of the HadCRUT surface temperature record and other CRU datasets; (d) the validity of the recent surface temperature record as constructed by the National Oceanographic and Atmospheric Administration (NOAA) and National Aeronautics and Space Administration (NASA); and (e) the implications of new studies not previously considered. Each of these issues is addressed in general here and in fuller detail in the Volume 1 of the RTP document.

a. Validity of Paleoclimate Temperature Reconstructions and Attribution of Observed Temperature Trends to Greenhouse Gases

Petitioners raise various claims about the comparisons of current temperatures with historic temperatures of the distant past (called paleoclimate temperature reconstructions). Petitioners use these claims to contest the view that current warming is unusual and argue that EPA should not rely on this evidence to support the statement in the Endangerment Finding that recent warming can be primarily attributed to increased atmospheric concentrations of greenhouse gases caused by human emissions. EPA addresses these claims in Volume 1, section 1.1 of the RTP document, and summarizes the responses here.

As background, surface temperature records based on observation have global coverage over approximately the last 150 years. To determine temperatures in time periods before the instrumental record, climate scientists use indirect methods called “proxies.” These indirect methods include examining tree rings, pollen, plankton records in sediment cores, and other proxies such as atomic isotope ratios in corals and other marine organisms. The statistical relationships found between the proxy and regional temperatures over the past 150 years (

i.e.,

the period when the datasets overlap) are then used to extrapolate over the hundreds or thousands of years before instrumental

records. Researchers combine a number of different proxies from around the world to develop their temperature reconstructions of the past. The further back in the past, the fewer proxies that exist and the greater the uncertainty becomes about estimating past temperatures. These reconstructions contribute to our understanding of historical temperatures and variability and enable comparison of present changes to changes in the past. They also allow testing of climate models and our understanding of how the climate system responded to historical conditions. The term “divergence” refers to a certain subset of the tree ring records whose growth in recent decades no longer correlates with (

i.e.,

it “diverges” from) temperature change in recent decades.

Petitioners claim the CRU e-mails provide new reason to highlight this divergence issue as it may undermine the use of historical temperature reconstructions. EPA disagrees, and finds that the CRU e-mails demonstrate that the scientists were well aware of the divergence issue and addressed it appropriately in their research and publications. A cursory examination of this literature and the assessment reports makes clear that the science community has long been aware of the tree ring divergence issue, as well as other issues concerning the certainty of proxy reconstructions. The uncertainties in the proxy reconstructions were fully presented in the assessment literature, and were considered by EPA in making the Endangerment Finding. In fact, during public comment on the proposed Finding, EPA evaluated and responded to these issues (See EPA RTC, Volume 2, comments 2-64 and 2-67). A recent NRC assessment (2006)

focused specifically on surface temperature reconstructions and it found that divergence is not an issue with all tree ring proxies, much less the many non-tree ring proxies used in the temperature reconstructions. The petitioners cite some studies

in support of their views that the divergence issue was hidden and not appropriately acknowledged. These studies do not support the petitioners' arguments, instead stating that the divergence problem is neither new nor hidden, that it is actually “widely perceived” and that the “potential consequences [are] discussed (

e.g.,

IPCC, 2007).”

National Research Council (NRC) (2006). Surface Temperature Reconstructions For the Last 2,000 Years. National Academy Press. Washington, DC.

D'Arrigo, R.

et al.

(2008). On the “divergence problem” in northern forests: a review of the tree-ring evidence and possible causes, 60 Glob. Planet. Chng. 289. Esper, J. and D. Frank (2009). Divergence pitfalls in tree-ring research. Clim. Chng. 94: 261, 262.

Nonetheless, petitioners allege that a number of the CRU e-mails suggest that these temperature reconstructions were manipulated and that data has been hidden. Several petitioners refer to an e-mail including the phrase “Mike's Nature trick”, claiming that this quote is evidence of deception. However, this e-mail about how to connect tree ring data and thermometer data was written in 1999, prior to the publication of the IPCC Third Assessment Report from 2001. The e-mail refers to a graph prepared for the front cover of World Meteorological Organization (WMO) report, unrelated to IPCC, published in 2000. This graph and underlying analysis that is being objected to by petitioners has no relevance to the discussion in either IPCC AR4 or EPA's TSD, and therefore did not enter into the Administrator's consideration for the Endangerment Finding. The IPCC AR4 and other assessment literature very transparently document, illustrate, and discuss the divergence issue, as did EPA in the TSD and RTC document. See Figure 4.3, TSD. Other quotes provided by the petitioners do not support a claim of “deliberate manipulation” or “artificial adjustments” when considered in context. This issue of historic temperature reconstructions is discussed in detail in Volume 1 of the RTP document. The UK Independent Climate Change E-Mails Review reached a similar conclusion to EPA's, stating that they “do not find that the way that data derived from tree rings is described and presented in IPCC AR4 and shown in its Figure 6.10 is misleading” and regarding the phenomenon of divergence that they “are satisfied that it is not hidden and that the subject is openly and extensively discussed in the literature, including CRU papers.”

Petitioners also claim that the Medieval Warming Period may have been warmer than present temperatures, undermining the conclusion that greenhouse gases are a primary cause of current warming. Issues involving the Medieval Warming Period were addressed during the public comment period (see Response 2-62 of the RTC document). Petitioners raise this issue again because of their assertion that the CRU e-mails indicate that the current temperature record may be faulty, which to them gives the Medieval Warming Period new significance. In making their case, petitioners cite a temperature reconstruction without tree rings, notably a study that could have been submitted during the public comment period.

However, that paper uses an improper methodology, a straight average of 18 proxies, apparently without weighting them to account for geographic distribution or the strength of the data to detect temperature changes. In contrast, another study using a more sophisticated methodology

found that recent Northern Hemispheric warmth was anomalous regardless of whether tree ring data were included.

Loehle, C. and J. H. McCulloch, 2008. Correction to: A 200-year global temperature reconstruction based on non-tree proxies. Energy & Environment. 19(1): 93-100.

Mann, M.E.

et al.

(2008). Proxy-based reconstructions of hemispheric and global surface temperature variations over the past two millennia. PNAS. 105:36.

Petitioners argue that if the current warming is not “unprecedented,” our ability to attribute the current warming to greenhouse gases is undermined, and that EPA has not provided “compelling” evidence that the current temperatures are unusual compared to the last 1,000 years. Petitioners misstate EPA's conclusions and overstate the role of this line of evidence. EPA has not claimed that current warming is “unprecedented”; the Administrator's Endangerment Finding stated that “The second line of evidence arises from indirect, historical estimates of past climate changes that suggest that the changes in global surface temperature over the last several decades are unusual.” (74 FR 66518) EPA found the scientific evidence “supports” this conclusion (see for example section 4 of the TSD), not that it compels it, as petitioners incorrectly assert. EPA clearly characterized the uncertainty in this line of the evidence, properly stating that there is significant uncertainty in the temperature record prior to 1600 A.D. (see section 4(b) of the TSD).

This comparison to past temperature estimates is also only one part of the paleoclimate evidence. Other parts, not contested by petitioners, include (1) the correlation and interactions over time between periods of higher greenhouse gas concentrations and higher temperatures, and (2) the use of temperature reconstructions to evaluate and improve climate models. Overall, this comparison of current to past temperatures is but one part of one line of evidence in attributing current warming to greenhouse gases; it is not the primary line of evidence. The petitioners have not shown that EPA failed to properly characterize this evidence, and the petitioners' assertions regarding EPA's treatment and reliance

on this evidence are inaccurate and misleading.

Petitioners claim that characteristics of trends in the vertical temperature profile of the atmosphere should present a “fingerprint” of human-induced warming, and that this expected fingerprint has not been observed in the tropics, and that therefore the attribution of recent warming to human causes is placed into doubt. However, EPA recognized and already addressed this issue in the TSD (see section 5(a) of the TSD) which notes newer data sets are in general agreement with climate models in the tropics and therefore there is no longer an inconsistency. In addition, petitioners do not contest any of the other important pieces of evidence that link current warming to greenhouse gases, such as rates of sea level rise and Arctic ice loss.

Petitioners claim that the projections from climate models do not support attribution to greenhouse gases because the models have not explained why there may have been a slowdown in the rate of warming over the last 10 or so years. First, according to the latest NOAA (2010) data,

the decade spanning 2000-2009 was substantially warmer than the prior decade (1990-1999) (see also the figure in Response 1-22 in Volume 1 of the RTP document). The exact rate of warming in the past decade depends on one's choice of temperature record and the start and stop date chosen for computing a trend in that record. Second, whether models can reproduce a short-term slowdown in the warming in no way invalidates their use for attributing or projecting long-term changes in global climate from anthropogenic forcing of the climate system. The latter long-term projections are their primary purpose, not year-to-year projections of changes over a period of around a decade or less. In addition, recent studies indicate that short-term trends can run counter to overall long term trends, and the climate models can reproduce this.

http://www.ncdc.noaa.gov/sotc/?report=global&year=2009&month=13&submitted=Get+Report#gtemp.

The IPCC, NRC, and EPA's TSD appropriately reflect the state of the science and discussed the areas of uncertainty in temperature reconstructions. They fully considered the entire body of evidence, including the kinds of evidence and arguments presented by petitioners. In contrast, petitioners generally have not considered the breadth of evidence on these issues, and they fail to acknowledge the comprehensive treatment of these issues in the assessment reports. They have instead relied upon a limited selection of information that does not warrant the broad conclusions they draw.

Petitioners' evidence does not materially change or warrant any less reliance on the other important lines of evidence linking greenhouse gases and climate change: Our basic physical understanding of the effects of changing greenhouse gas concentrations and other factors; the broad, qualitative consistency between observed changes in climate and the computer model simulations of how climate would be expected to change in response to anthropogenic emissions of greenhouse gases (and aerosols); as well as other important evidence of an anthropogenic fingerprint in the observed warming.

b. Validity of the HadCRUT Surface Temperature Record

Petitioners present five major arguments regarding the validity and use of the HadCRUT temperature record. In particular, they claim that: (1) Alleged destruction of raw data for the HadCRUT temperature record renders the scientific data on surface temperature worthless and makes replication of temperature trends impossible; (2) comments within code and log files are evidence of manipulation that “undercuts the credibility of CRU databases;” (3) a report allegedly claims to show that the Russian stations used in the HadCRUT temperature record were selectively chosen to show increased warming; (4) the IPCC improperly relied on Jones

et al.

(1990)

for its conclusions about the magnitude of the urban heat island effect; and (5) the allegedly faulty HadCRUT temperature record is the primary basis for the conclusion of “unprecedented” warming and the foundation of anthropogenic global warming analyses. In effect petitioners use these claims to contest the existence or amount of recent warming.

Jones, P.D., P.Y. Groisman, M. Coughlan, N. Plummer, W.-C. Wang, and T.R. Karl (1990). Assessment of urbanization effects in time series of surface air temperature over land. Nature 347:169-172.

As background, monitoring the changes in the Earth's surface temperature is only one of several key components of studying climate change. Other indicators of climate change include receding glaciers, shrinking Arctic sea ice, and sea level rise, as well as a number of other temperature-sensitive physical and biological changes, such as bird migration patterns and changes in the length of the growing season.

Surface temperature records are built on data collected from thousands of weather stations around the world, as well as sea surface temperature records taken by ships crossing the ocean on different routes, with some data going back more than 100 years. Because the data originates from many international sources, some quality control is required such as checking for and deleting data that are shown to be duplicate, or adjusting to account for inconsistent reporting methodologies. Additionally, these weather stations and their data were not originally intended to be used for long-term climate monitoring, and sometimes adjustments are necessary to avoid confusing a local artificial temperature change (e.g., due to a shift in the elevation of a monitoring station) with large-scale or global temperature patterns.

The three major temperature record developers, CRU, NOAA, and NASA, all use different approaches for these adjustments. The approach by CRU is the only one of the three that relies on a substantial set of manual adjustments globally. NOAA uses an automated algorithm to adjust for discontinuities such as might be expected from station moves, with additional corrections in the U.S. because a large number of stations changed measurement instrumentation as well as the time of day of temperature readings. NASA uses NOAA's adjustments for the U.S. as an input, but uses an algorithm that identifies urban centers based on satellite observations and adjusts those urban centers to have trends that are consistent with nearby rural stations. In addition, the data are not evenly situated around the planet, and need to be extrapolated and averaged so that areas with many stations are not overrepresented and areas with few stations are not underrepresented. The kinds of adjustments made to the underlying raw data are designed so that the surface temperature analyses reflect as much as possible the actual direction and magnitude of any change in surface temperature and do not reflect other changes, such as changes in measurement devices.

The temperature reconstructions generally do not evaluate the average actual surface temperature, but rather determine the changes in temperature, both regionally and globally. The emphasis on changes in temperature is important, because they are better correlated with large regional changes. For example, two nearby stations—one on top of a mountain and one in the valley—will likely have different absolute temperatures, but are likely to

have similar changes in temperature over time.

CRU also maintains a dataset known as TS3.0, with TS2.1 as an older version. This dataset is different from HadCRUT, and includes various climate metrics and data information not in HadCRUT. TS2.1 is referred to in IPCC AR4 only twice in relation to historical precipitation data. Almost all of the references to global temperatures over time that refer to CRU data refer to the HadCRUT temperature record, and not the TS3.0 or 2.1 datasets.

(i) Raw Data.

Several petitioners claim that CRU has not kept all of the raw data from the surface weather stations, only the adjusted data, e.g. corrected for station moves and measurement changes, and therefore the evidence for warming in the past century is questionable and cannot be independently replicated.

CRU acknowledges that it did not keep a small percent of the raw weather station data collected since the 1980s and that it cannot release other raw data because of agreements with national meteorological organizations. CRU has provided a detailed explanation for its handling of the data, and EPA already addressed this issue at length in Response 2-39 of the RTC. Not retaining a small amount of the raw data does not interfere in a material way with replication or development of independent estimates of global or regional surface temperature history. The vast majority of the raw weather station data is indeed publicly available from the Global Historical Climate Network (GHCN) and other public data sources, contrary to the petitioners' assertions. An independent estimate of global temperatures can be generated, as NASA/GISS, NOAA/NCDC, and other groups have done. The separate NASA and NOAA analyses of global surface temperature records find similar temperature increases and strongly support the conclusion that the HadCRUT surface temperature record accurately reflects the changes in temperature. The UK Independent Climate Change E-Mails Review was able to download raw data and produce global temperature trend results similar to the other analyses in less than two days. In addition, the major conclusions about warming based on the HadCRUT temperature record have remained robust, even as CRU integrated more data and refined its methodologies over two decades.

The petitioners do not provide any global analysis of the available data from temperature stations that yields a different result. Further, they have provided no evidence that an additional or different analysis using the publicly available temperature data would yield a different result from the warming reflected in the HadCRUT, NOAA and NASA analyses of global surface temperature. It is an unwarranted leap in logic to assume these analyses have no merit because a small percentage of the underlying raw data is no longer in CRU's possession.

(ii) Biased Methods.

Petitioners claim the various methods that CRU used to integrate and adjust the surface temperature data introduce biases in the temperature record that were designed to support the view that global surface temperatures are increasing faster than they actually are. The petitioners refer to this as “manipulation” and cite several CRU e-mails and other documents as support. A couple of fragments of code and a debugging log (

HARRY_READ_ME.txt

) are quoted extensively as support for these claims.

EPA has thoroughly reviewed all of the disclosed CRU e-mails in light of the petitioners' claims, and EPA responds to all of the petitioners arguments in detail in Volume 1 of the RTP document. Here, EPA focuses on two of the most well-known CRU documents:

BRIFFA_SEPT98_.PRO

and

HARRY_READ_ME.txt.

The code fragment

BRIFFA_SEPT98_E.PRO

that includes a comment in the header for the code that states that the code “APPLIES A VERY ARTIFICIAL CORRECTION FOR DECLINE” is over a decade old and appears to be provisional test code. The comments in capital letters are to remind the programmer to replace the temporary fudge factors with more valid adjustments before the code is used for public products. It further appears that the “fudge” factor highlighted by petitioners is not related to the HadCRUT temperature record, but instead refers to the divergence issue discussed above and the unrelated WMO report. The petitioners do not show that the

BRIFFA_SEPT98_E.PRO

code has any relationship to the HadCRUT temperature record or that it was actually used for any public final product.

The

HARRY_READ_ME.txt

debugging notes are a record of attempts to update the CRU TS product by merging six years of additional data to an old data set and migrating the code to a new computer system at the same time. The petitioners fail to acknowledge that the CRU TS products are different from the HadCRUT temperature record that is referred to in the assessment reports and the EPA TSD, and they improperly assert that issues with the TS products directly call into question the HadCRUT temperature record. The file referred to by petitioners does indicate that there were a number of difficult quality control issues that had to be addressed concerning new data, the code written for the updating process, and the old code for producing TS2.1. The full debugging log demonstrates that a number of the identified problems were successfully fixed. Many of the quotes highlighted by petitioners were expressions of frustration that were not related to the quality of the product. A number of the problems were related to inconsistencies involving reported WMO codes used to identify weather stations. These inconsistencies have previously been highlighted in the literature, and the approach to address them as related in the log file was similar to the approaches detailed in previous papers. In sum, the

HARRY_READ_ME.txt

file is focused on issues that do not relate to the HadCRUT temperature record and contains no evidence of any attempts to bias any output data.

(iii) Biased Dataset.

Petitioners claim that CRU scientists selectively chose Russian data stations to create a biased dataset that would show more warming than would the full dataset. To support this argument, they provide a link to a translation (hosted at a blog) of a report written in Russian by the Institute for Economic Analysis in Moscow (Pivovarova, 2009).

Pivovarova, N. (2009). Institute for Economic Analysis (IEA): How warming is made. The case of Russia. (December 15, 2009). Available at:

http://www.iea.ru/article/kioto_order/15.12.2009.pdf;

translation at:

http://climateaudit.files.wordpress.com/2009/12/iea1.pdf.

Last accessed on April 26, 2010.

Examination of this document indicates that the Moscow Institute for Economic Analysis temperature record using the full set of Russian stations agrees well after 1955 with the temperature record that the Institute derived from the set of stations used in the HadCRUT temperature record, and that the difference between temperature records derived from the two datasets is mainly in the 1850 to 1950 portion. However, the method used by the Institute for Economic Analysis to compare the two temperature datasets was an improper comparison of apples and oranges (i.e., the HadCRUT temperature record uses a different geographic weighting approach than did the Institute for Economic Analysis, which is more important when the data is sparse as it is before 1955).

Petitioners also do not support their claim that CRU selectively picked stations. EPA has found no evidence in

the CRU e-mails or the information provided by petitioners to indicate that stations were chosen by CRU scientists. CRU uses a number of data sources and the petitioners did not assess whether these data sources included the missing Russian stations, or whether the stations met criteria discussed in published papers (see volume 1 of the RTP document).

(iv) Urban Heat Island Corrections.

Petitioners criticize the urban heat island corrections as another alleged example of temperature data manipulation.

This issue is not new. EPA addressed urban heat island issues in responses 2-28 through 2-30 of the RTC document. Referencing Jones

et al.

(1990)

and other studies, IPCC AR4 concludes that “urban heat island effects are real but local, and have not biased the large-scale trends.” In addition, satellite records are not susceptible to urban heat island effects and globally show similar trends to land-based measurements over their overlapping time period. EPA summarized this information in the TSD. EPA's specific responses to the petitioners' arguments are provided in Volume 1 of the RTP document.

Jones, P.D., P.Y. Groisman, M. Coughlan, N. Plummer, W.-C. Wang, and T.R. Karl (1990). Assessment of urbanization effects in time series of surface air temperature over land. Nature 347:169-172.

(v) Faulty Temperature Record Used by IPCC.

Petitioners claim the allegedly faulty HadCRUT temperature record is the primary or core support for IPCC conclusions on current warming, attribution, and projections of future warming, thus calling into question the fundamental conclusions of IPCC AR4 and EPA's use of IPCC AR4 as a primary reference to support the Endangerment Finding.

First, for reasons stated above and detailed further in Volume 1 of the RTP document, EPA disagrees with the petitioners' claims that the HadCRUT temperature record is faulty. Second, as noted previously, multiple independent assessments of climate change science by not only the IPCC but also USGCRP and NRC have concluded that warming of the climate system in recent decades is “unequivocal.” This conclusion is not drawn from any one source of data, but is based on a review of multiple sources of data and information, which includes the HadCRUT temperature record, additional temperature records from other sources, and numerous other independent indicators of global warming (see section 4 of EPA's TSD).

NOAA and NASA surface temperature records show nearly identical warming trends to the HadCRUT temperature record, despite different analysis methodologies. Moreover, entirely independent records of lower tropospheric temperature measured by both weather balloons and satellites demonstrate strong agreement with the surface temperature records of all three organizations. The TSD also discussed the following additional indicators of global warming:

• Increasing global ocean heat content (Section 4(f) of the TSD).

• Rising global sea levels (Section 4(f) of the TSD).

• Shrinking glaciers worldwide (Section 4(i) of the TSD).

Changes in biological systems, including poleward and elevational range shifts of flora and fauna; the earlier onset of spring events, migration, and lengthening of the growing season; and changes in abundance of certain species (Section 4(i) of the TSD).

It is this entire body of evidence that supports the conclusion that there is an unambiguous warming trend over the last 100 years, with the greatest warming occurring over the past 30 years. Contrary to petitioners' claims, the models used to generate projections of future warming described in IPCC AR4 do not directly rely on the HadCRUT or other surface temperature records. These models are driven by physical equations describing the radiative properties and dynamics of the atmosphere and oceans and parameterizations of small-scale processes, not observed temperature data.

In summary, EPA disagrees with the premise of this claim—that the HadCRUT temperature record is faulty—and therefore disagrees that use of the HadCRUT temperature record within IPCC AR4 has somehow corrupted the IPCC's conclusions. In addition, the petitioners' claim that the HadCRUT temperature record is such a central thread to the entire IPCC AR4 that this would then invalidate all IPCC AR4 conclusions is unsupported and exaggerated.

c. Validity of NOAA and NASA Temperature Records

A number of petitioners question the validity of NOAA and NASA surface temperature records, raising claims concerning station “drop-out,” flawed or manipulative adjustments to data, and a lack of independence between the three major surface temperature records. EPA's response clearly shows that (1) petitioners rely on a questionable, non-peer-reviewed source which contains a number of inaccurate statements and relies on a scientifically flawed analysis; (2) petitioners demonstrate a fundamental scientific misunderstanding of what issues actually would lead to either a warming or cooling bias in the temperature record; and (3) petitioners fail to acknowledge that climatic records other than land surface temperature records also show clear warming trends.

As background, one of the sources of data for the HadCRUT temperature record is the GHCN, which was developed and is maintained by NOAA. The GCHN dataset is also used by both NOAA and NASA in their surface temperature records. NOAA, NASA, and CRU each calculate global surface temperature trends from a combination of GHCN data and other data sources. Each group performs different adjustments and corrections to the data, and in some cases uses different subsets of the GHCN data or includes other outside datasets.

Petitioners contest certain individual aspects or details of the surface temperature evidence, and in general raise objections that fail to recognize the various approaches used to develop the global surface temperature record. Many of the issues raised by the petitioners are not new, and have been addressed previously within the TSD and RTC document. Some objections fail to recognize that the change in temperature is being evaluated, not the absolute temperature level. Other objections misconstrue the underlying studies cited by the petitioners. In several cases, petitioners object that various adjustments to the raw data have the effect of changing the data, but they fail to consider that adjustments are appropriately performed, for example, to account for circumstances that otherwise would interfere with accurately isolating and determining a real trend in surface temperature. Petitioners fail to address the reasons behind the adjustments and fail to explain or show that the types of adjustments made in developing such datasets from multiple sources of data are not appropriate. Likewise, petitioners fail to account for the valid data-driven reasons that have led to a reduction over time in the number of weather stations used for the surface temperature analysis, fail to explain or show that the reductions have biased the temperature record, and overstate the magnitude of the temperature station reductions in some cases.

Consistency between all three separate surface temperature records (NASA, NOAA, CRU), as well as consistency between the three surface temperature records and other evidence of warming, such as satellite data, ocean

temperature data, and physical evidence of the effects of warming, should be seen as confirmation of the evidence of warming. Petitioners appear to assume that all of this evidence must be wrong because they, incorrectly (see above), allege that some of it is.

(i) Station Drop-out.

Petitioners raise a number of issues regarding the alleged “drop-out” of stations after 1990, and the extrapolation of data from “warmer” areas to “colder” areas due to this drop-out or for other reasons. They claim this leads to bias in the global surface temperature record. Volume 1, section 1.4.3.1 of the RTP document addresses these claims in detail, and EPA's summary of the issue follows.

Many of the petitioners' arguments rely on a non-peer-reviewed document by D'Aleo and Watts (2010).

However, the study and the source upon which it relies do not support petitioners' claims and conclusions. D'Aleo and Watts (2010) provide no evidence that there was a systematic and purposeful “weeding out” process. Peterson and Vose (1997),

the paper describing the GHCN dataset, describes the procedures for updating the GHCN database and explains that there are fewer measuring stations post-1992 than during the 1980s because only three of the data sources were being be updated on a regular basis.

D'Aleo and Watts (2010). Surface Temperature Records: Policy Driven Deception? Available at:

http://scienceandpublicpolicy.org/originals/policy_driven_deception.html.

Accessed: April 8, 2010.

Peterson, T. C. and R. S. Vose (1997). An overview of the global historical climatology network temperature data base. Bull. Am. Met. Soc., 78: 2837-2849.

The D'Aleo and Watts study assumed that dropping stations at higher latitudes and in colder climates would result in a biased, warmer temperature trend. This unfounded assumption is a misunderstanding of the basic methodology used in analyzing surface temperature data. The surface temperature record sets evaluate the change in temperature over time at the various stations, not the absolute temperature level. The change in temperature over time is what indicates whether warming is occurring, not just the absolute temperature itself; for example, the Arctic region has been experiencing the highest rates of warming in the world, yet average Arctic temperatures are obviously still considerably colder than temperatures in most other world regions where average temperatures may not have increased as much. Petitioners incorrectly assume and do not explain why dropping these stations would bias the trend in the change in temperature toward greater warmth. In fact, petitioners fail to acknowledge that colder, high latitude areas are the regions of the world where the most warming is occurring, and is expected to continue occurring. If one were to accept this line of the petitioners' original argument, there should have been concern about a bias towards less warming, not more warming.

Moreover, the D'Aleo and Watts study used simple averages of absolute temperatures at the stations—without, apparently, taking into account their geographic distribution, much less calculating the change in temperature at the stations. This improper methodology is a significant error that undermines the petitioners' critique of the temperature records.

Furthermore, satellite data is available for the time periods of land-based station “drop-out”, and the satellite temperature record is broadly consistent with surface temperature trends throughout the period when the “drop out” was occurring, confirming that the reduction in the number of data stations has not created a warming bias. Additionally, analyses using only stations with continuous records are almost identical to analyses using only stations which were “dropped” over the decades before the “drop-out”, further undermining the petitioners' claim that a warming bias was introduced by the station “drop-out”.

(ii) Improper Heat Island Adjustments.

Petitioners assert that the urban heat island adjustments performed by NASA are insufficient or improperly applied, both globally and in the U.S. Southeastern Legal Foundation points to the study Long (2010)

as support for this assertion. These assertions are addressed in detail in volume 1, section 1.4.3.2 of the RTP document, and EPA's general response is summarized here.

Long, E.R. (2010). Contiguous U.S. Temperature Trends Using NCDC Raw and Adjusted Data for One-Per-State Rural and Urban Station Sets. Available at

http://scienceandpublicpolicy.org/images/stories/papers/originals/Rate_of_Temp_Change_Raw_and_Adjusted_NCDC_Data.pdf.

Accessed April 8, 2010.

The Long (2010) study found that the net effect of NOAA adjustments to the raw data led to more warming in rural stations (the NOAA adjustments for the U.S. are also used in developing the NASA temperature record). Neither the petitioners nor Long show, however, that the adjustments to rural stations were inappropriate. (As stated above, adjustments are sometimes necessary to ensure a real, and not artificial, temperature change is being recorded when, for example, there might be a change in the elevation of the station or the daily timing of temperature readings.) Importantly, Long does not take into account either the changes in the time of observation or the changes in instrumentation at many rural stations, both of which led to temperature discontinuities that must be accounted for (

e.g.,

through adjustments) in order to accurately portray the actual long-term temperature trend.

With respect to the claimed failure to account for the urban heat island effect (where metropolitan areas tend to be warmer than surrounding areas due to built up land surfaces and building materials that retain heat), this issue was raised previously during the public comment period and EPA has addressed this in the RTC document. Response 2-28 of the RTC document makes clear that all of the different surface temperature datasets shown or cited in the TSD account for the urban heat island effect, either directly and/or indirectly. The TSD, citing IPCC (Trenberth

et al.,

2007), summarized this issue as the following: “ * * * urban heat island effects are real but local, and have not biased the large-scale trends.” Note also that the oceans are warming and that the most rapid land-based warming is occurring in the Arctic, two areas where urban heat island effects are obviously not an issue.

(iii) Data Adjustments.

Petitioners cite the records of some individual stations that they claim show inappropriate manipulation, referring to stations in Australia and New Zealand.

The evidence and arguments about data adjustments in New Zealand do not support the claim that these adjustments were invalid, after taking into account station history and neighboring station records. While there is some evidence that the automated algorithm may have introduced a spurious trend in one station in Australia in the NOAA temperature record (but not in the CRU or NASA temperature records), there was at least one valid reason for adjustment, and there is no evidence that this error in one station biases the large-scale global temperature trends. There is certainly no evidence of “chicanery” involved in these adjustments, as one petitioner claimed.

Petitioners focus on individual stations or limited areas. It is not surprising that data from one station or one region would show a large difference between adjusted and unadjusted data. The important point is that when the stations and regions are combined for a global analysis, these

kinds of effects are balanced out and do not produce a bias in the overall result. EPA addresses these issues for the specific station data at issue in New Zealand and Australia in greater detail in Volume 1, section 1.4.3.4 of the RTP document.

(iv) Independence of the NOAA and NASA Temperature Records. Some petitioners claim that the NOAA and NASA temperature records are not independent from the HadCRUT temperature record, developed by CRU, because they share some of the same raw data, and thus are assumed to also share some of the same alleged problems. EPA addresses these claims in volume 1, section 1.4.3.5 of the RTP document, and summarizes the response here.

The three major temperature records do rely on a large amount of raw data obtained from GHCN, though the HadCRUT temperature record in particular integrates additional data obtained from other, independent sources. As discussed above and throughout volume 1 of the RTP document, petitioners have not demonstrated any major flaws in the raw data. In addition, the processing of the GHCN data by the three groups is carried out independently from one another; therefore the similarities of the final temperature trends among the three groups provide additional confidence in those independent processing methodologies, and additional confidence in the consistent result that average global temperatures are increasing.

d. Implications of New Studies and Data Submitted by the Petitioners

Several petitioners identify scientific studies most (but not all) of which were published around the time of or shortly after the Administrator's December 2009 Endangerment Finding, as well as data not previously considered as part of the scientific record for the Endangerment Finding. Petitioners argue these studies and data have the potential to alter our understanding of key aspects of the science and therefore warrant reconsideration of the Findings. Petitioners also argue that EPA ignored or misinterpreted scientific data that were significant and available when the Finding was made. These studies and data issues involve:

• Implications of a new study on stratospheric water vapor.

• Implications of material concerning whether carbon dioxide is well-mixed in the atmosphere and whether the airborne fraction of carbon dioxide has changed.

• Implications of new tropical cyclone studies.

• Implications of new data on observational snow cover trends.

• A claim that EPA ignored a satellite dataset.

Though some of these studies are new, they do not raise new issues that had not already been accounted for in the assessment literature used by EPA. Furthermore, petitioners misinterpret the findings of these new studies, make unsupportable claims, rely on incomplete and biased analyses, do not acknowledge important results, and, at times, ignore EPA's record. Contrary to the petitioners' claims, the new science cited by the petitioners does not undermine the key findings and conclusions that were reached in the assessment literature and the scientific foundation for the Administrator's Findings. EPA's study-by-study responses to the petitioners' assertions can be found in volume 1, section 1.5 of the RTP document.

2. Issues Raised by EPA's Use of the IPCC AR4 Assessment

The objections raised by petitioners involving EPA's use of IPCC AR4 include (a) claims that recently found errors in IPCC AR4 undermine the IPCC's credibility and therefore EPA's use of IPCC AR4 as a primary reference document to support the Findings; and (b) claims that the IPCC has a policy agenda and is not an objective scientific body. These issues are addressed here and in greater detail in volume 2 of the RTP document.

a. Claims That Errors Undermine the IPCC AR4 Findings and Technical Support for Endangerment

The petitioners allege certain errors and unsupported statements in IPCC AR4 show that the science EPA relied upon is uncertain and/or not credible. Petitioners focus on the errors found regarding the timing of future projected melting of Himalayan glaciers, the percentage of the Netherlands below sea level, and a few more minor issues highlighted in the petitions. Each of these identified and alleged errors in IPCC AR4 has been examined in detail by EPA in Volume 2 of the RTP document; the general response is provided here.

EPA has reviewed these IPCC AR4 issues in the context of the key IPCC AR4 conclusions that were germane to the Administrator's Endangerment Finding. The small number of errors and alleged errors in the IPCC AR4 report are not materially relevant for EPA's Endangerment Finding. Neither of the two errors that are verifiable (Netherlands sea level and Himalayan glaciers) are relevant to impacts in the United States and neither are part of the basis for the Endangerment Finding. Furthermore, there is no evidence that these two confirmed minor errors are an indication of a more serious problem with the quality and reliability of any other findings and conclusions from the IPCC AR4, including those that are relevant for the Endangerment Finding.

The remaining alleged errors, taken from non-peer-reviewed (“gray”) literature, do not appear to be errors according to EPA's review. The IPCC provides guidance on how and when to use gray literature, and petitioners do not demonstrate that the guidance was not followed. Gray literature is not automatically incorrect or suspect, and an examination of the particular gray literature sources demonstrates that the petitioners' allegations regarding these alleged errors are unfounded. Furthermore, the IPCC AR4 statements at issue have no material relevance to EPA's Findings. Below are brief responses as to why the petitioners' assertions based on these known and alleged errors are unfounded and exaggerated. Additional detail on these issues is contained in Section 2.1, Volume 2 of the RTP document.

(i) Percent of the Netherlands Below Sea Level

The IPCC AR4 erroneously stated that 55 percent of the Netherlands is below sea level, whereas the actual number is only 26 percent. The statistic quoted in the AR4 was inaccurate, and a correction was published by the Netherlands Environmental Assessment Agency. What should have been stated is that 55 percent of the Netherlands is at risk of flooding; 26 percent of the country is below sea level, and 29 percent is susceptible to river flooding. The error originated with the Netherlands Environmental Assessment Agency, not the IPCC. The IPCC published an official erratum (IPCC, 2010b)

correcting the mistake, and noted “The sea level statistic was used for background information only, and the updated information remains consistent with the overall conclusions.”

IPCC (2010b). Fourth Assessment Report: Working Group II Erratum. Intergovernmental Panel on Climate Change (IPCC). 26 Jan. 2010.

http://www.ipcc.ch/publications_and_data/ar4/wg2/en/errataserrata-errata.html.

EPA does not refer to or rely on this statistic in the Findings and the percentage of the Netherlands below sea level does not pertain to the endangerment of public health and welfare in the United States. This error is very minor and has no impact on the

climate science and health and welfare impacts supporting EPA's Endangerment Finding. Furthermore, there is no evidence that this minor error is somehow, as the petitioner would allege, an indication of flawed science and poor quality control practices sweeping across all conclusions of IPCC AR4.

(ii) Himalayan Glacier Projection

Several petitioners state that the IPCC AR4 erred in projecting that glaciers in the Himalayas would disappear by 2035, and that EPA relied on this projection.

The IPCC did inaccurately state the year 2035 in that particular statement. The IPCC issued a correction concerning the melting of Himalayan glaciers (IPCC, 2010c)

which also found that its general conclusion (provided below) on this issue remains robust and “entirely consistent with the underlying science.”

IPCC, 2010c. IPCC Statement on the Melting of Himalayan Glaciers, January 20, 2010.

http://www.ipcc.ch/pdf/presentations/himalay

This text is long and has been trimmed here. Open the source document for the complete record.

This is a copy of a public record, reproduced as it was published. It is not legal advice, and it may not be the version a court would rely on. Check the official source before you cite it.