6560.50

ENVIRONMENTAL PROTECTION AGENCY 

40 CFR Chapter 1 

[EPA-HQ-OAR-2009-0171; FRL xxxx-x] 

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 
Page 2 of 217

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. 

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 www.regulations.gov website. 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 

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. 
Page 3 of 217

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. 

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 

CH4 methane 

CO2 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 
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HadCRUT Climatic Research Unit (CRU) temperature record 

ICTA International Center For Technology Assessment 

IPCC Intergovernmental Panel on Climate Change 

MWP Medieval Warm Period 

N2O 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 

NOx 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 v. EPA 

2. Post-Massachusetts v. 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 
Page 5 of 217

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
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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 
Page 7 of 217

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)1, and submissions of a limited number of additional 

studies not previously considered as part of the scientific 

record of the Endangerment Finding. 

 

1

 IPCC (2007). Fourth Assessment Report: Climate Change 2007. Cambridge 

University Press, Cambridge, United Kingdom and New York, NY, USA. 
Page 8 of 217

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 
Page 9 of 217

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 email communications between scientists at the Climatic 
Page 10 of 217

Research Unit (CRU) of the University of East Anglia in the 

United Kingdom and several other scientists (“the CRU emails”)2. 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. 

Inquiries from the UK House of Commons, Science and 

Technology Committee, the University of East Anglia, 

Oxburgh Panel, the Pennsylvania State University, and the 

 

2

 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.” 
Page 11 of 217

University of East Anglia, Russell Panel3, 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 emails. 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. 

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 

 

3

 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.” 
Page 12 of 217

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 
Page 13 of 217

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 studyby-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 Change4” (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 

 

4

 National Research Council (NRC) (2010). Advancing the Science of 

Climate Change. National Academy Press. Washington, DC. 
Page 14 of 217

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. 

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 
Page 15 of 217

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).5 

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 

 

5

 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. 
Page 16 of 217

by a Technical Support Document (TSD)(Docket EPA-HQ-OAR2009-0171-11645), 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-OAR2009-0171) 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 
Page 17 of 217

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--CO2, CH4, N2O, and HFCs--constituted 
Page 18 of 217

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 CO2 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 CO2 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 
Page 19 of 217

the ICTA Petition should be denied. To begin with, EPA 

found that requiring passenger cars and light trucks to 

emit less CO2, 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 CO2 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 CO2 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 CO2 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 
Page 20 of 217

inappropriate to regulate [greenhouse gas] emissions from 

motor vehicles.” Id. at 52,931. 

b. Massachusetts v. 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 v. EPA, 549 U.S. 

497 (2007). In Massachusetts v. 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 
Page 21 of 217

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 
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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. 
Page 23 of 217

2. Post-Massachusetts v. 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 v. 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 
Page 24 of 217

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 
Page 25 of 217

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 
Page 26 of 217

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.6 Nine of these petitions base their requests on 

allegations that developments since the close of the 

 

6

 The West Virginia Coal Association also filed a letter in support of 

the existing petitions for reconsideration. 
Page 27 of 217

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 LightDuty 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. 

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 
Page 28 of 217

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 
Page 29 of 217

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. 
Page 30 of 217

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 
Page 31 of 217

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 
Page 32 of 217

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 
Page 33 of 217

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. v. EPA, 684 F.2d 1007, 

1017-20 (D.C. Cir. 1982). 
Page 34 of 217

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 
Page 35 of 217

regulations would “have been significantly changed.” 

Kennecott, 684 F.2d at 1018-1019.7

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 

 

7

 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. 
Page 36 of 217

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.8 There is no 

 

8

 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 
Page 37 of 217

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. 

Appalachian Power Company et al. v. 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 

 

SLF with respect to the arguments and documents submitted to the agency 

after the end of the comment period, in the petitions to reconsider. 
Page 38 of 217

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 
Page 39 of 217

section 307(d)(7)(B)9. 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. 

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. 

 

9

 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. 
Page 40 of 217

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 
Page 41 of 217

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 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). 
Page 42 of 217

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. 
Page 43 of 217

(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 
Page 44 of 217

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. 
Page 45 of 217

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.10

1. What effects do greenhouse gases have on the 

environment and on climate in particular? 

 

10 National Research Council (2010) Advancing the Science of Climate 

Change: America’s Climate Choices, National Academies Press, 

Washington, DC. 
Page 46 of 217

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? 
Page 47 of 217

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 EPAHQ-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 
Page 48 of 217

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 CO2 

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 CO2 in the atmosphere can 

be linked to the composition of the CO2 emissions from 

fossil fuel burning. Moreover, analyses of bubbles trapped 

in ice cores from Greenland and Antarctica reveal that 

atmospheric CO2 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. 
Page 49 of 217

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? 

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/m2), 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 USGCRP11 reports 

attributed recent North American warming to elevated 

GHG concentrations. In the U.S. Climate Change 

 

11 USGCRP now encompasses the former Climate Change Science Program 

(CCSP) under the previous Administration. 
Page 50 of 217

Science Program (CCSP) (2008)12 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.” 

 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 CO2 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 

 

12 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. 
Page 51 of 217

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. 
Page 52 of 217

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 
Page 53 of 217

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)13. 

 

13 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 
Page 54 of 217

The IPCC’s First Assessment Report in 1990 contained little 

observational evidence of a detectable anthropogenic 

influence on climate (IPCC, 1990)14. 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)15. 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)16. The conclusion in IPCC’s 2007 Fourth 

Assessment Report (2007b)17 is the strongest yet: “Most of 

the observed increase in global average temperatures since 

the mid-20th century is very likely18 due to the observed 

increase in anthropogenic GHG concentrations.” 

 

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. 

14 IPCC (1990). First Assessment Report: Climate Change 1990. Cambridge 

University Press, Cambridge, United Kingdom and New York, NY, USA. 

15 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. 

16 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. 

17 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. 

18 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. 
Page 55 of 217

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)19 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: 

 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 

 

19 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. 
Page 56 of 217

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 
Page 57 of 217

and past climate changes (IPCC, 2007a)20. 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. 

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)21 state that when uncertainties 

in models and observations are properly accounted for, 

 

20 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. 

21 Karl, T., J. Melillo, and T. Peterson (Eds.) (2009) Global Climate 

Change Impacts in the United States. Cambridge University Press, 

Cambridge, United Kingdom. 
Page 58 of 217

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. 

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: 
Page 59 of 217

 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 CO2

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 computerbased 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. 
Page 60 of 217

 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. 
Page 61 of 217

 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. 
Page 62 of 217

 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 . 
Page 63 of 217

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 heatrelated mortality due to global warming in the United 

States are unlikely to be compensated for by decreases 

in cold-related mortality. 
Page 64 of 217

 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 CO2 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. 
Page 65 of 217

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. 
Page 66 of 217

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 
Page 67 of 217

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 
Page 68 of 217

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 wellmixed 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 climatesensitive 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 
Page 69 of 217

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, 
Page 70 of 217

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 
Page 71 of 217

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 
Page 72 of 217

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 
Page 73 of 217

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 
Page 74 of 217

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 
Page 75 of 217

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 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. 
Page 76 of 217

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 
Page 77 of 217

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 
Page 78 of 217

also conclude, based on a selective reading of the CRU emails, 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 
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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 
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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 
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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. 
Page 82 of 217

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 
Page 83 of 217

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 
Page 84 of 217

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)22 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 studies23 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).” 

 

22 National Research Council (NRC) (2006). Surface Temperature 

Reconstructions For the Last 2,000 Years. National Academy Press. 

Washington, DC. 

23 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. 
Page 85 of 217

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 
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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.24 However, that paper 

uses an improper methodology, a straight average of 18 

proxies, apparently without weighting them to account for 

 

24 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. 
Page 87 of 217

geographic distribution or the strength of the data to 

detect temperature changes. In contrast, another study 

using a more sophisticated methodology25 found that recent 

Northern Hemispheric warmth was anomalous regardless of 

whether tree ring data were included. 

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 

 

25 Mann, M.E. et al. (2008). Proxy-based reconstructions of hemispheric 

and global surface temperature variations over the past two millennia. 

PNAS. 105:36. 
Page 88 of 217

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 
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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,26 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-

 

26

http://www.ncdc.noaa.gov/sotc/?report=global&year=2009&month=13&submitt

ed=Get+Report#gtemp 
Page 90 of 217

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. 

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 
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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)27 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. 

 

27 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. 
Page 92 of 217

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. 
Page 93 of 217

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. 
Page 94 of 217

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. 
Page 95 of 217

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 

publically 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 
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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 

publically 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 emails 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. 
Page 97 of 217

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 
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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. 
Page 99 of 217

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)28. 

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). 

 

28 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. 
Page 100 of 217

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)29 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 

 

29 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. 
Page 101 of 217

responses to the petitioners arguments are provided in 

Volume 1 of the RTP document. 

(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). 
Page 102 of 217

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 
Page 103 of 217

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 
Page 104 of 217

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 
Page 105 of 217

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. 
Page 106 of 217

(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-peerreviewed document by D’Aleo and Watts (2010)30. 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)31, 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. 

 

30 D’Aleo and Watts (2010). Surface Temperature Records: Policy Driven 

Deception? Available at: 

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

l. Accessed: April 8, 2010. 

31 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. 
Page 107 of 217

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. 
Page 108 of 217

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 occuring, 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 
Page 109 of 217

(2010)32 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. 

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 

 

32 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. 
Page 110 of 217

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 landbased 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 
Page 111 of 217

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. 
Page 112 of 217

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 
Page 113 of 217

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 studyby-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
Page 114 of 217

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 
Page 115 of 217

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-peerreviewed (“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 
Page 116 of 217

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)33 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.” 

EPA does not refer to or rely on this statistic in the 

Findings and the percentage of the Neterlands 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 

 

33 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/errataserrataerrata.html 
Page 117 of 217

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)34

which also found that its general conclusion (provided 

below) on this issue remains robust and “entirely 

consistent with the underlying science.” 

Widespread mass losses from glaciers and reductions in 

snow cover over recent decades are projected to accelerate 

throughout the 21st century, reducing water availability, 

hydropower potential, and changing seasonality of flows in 

regions supplied by meltwater from major mountain ranges 

(e.g. Hindu-Kush, Himalaya, Andes), where more than onesixth of the world population currently lives. 

 

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

January 20, 2010. http://www.ipcc.ch/pdf/presentations/himalayastatement-20january2010.pdf. 
Page 118 of 217

 EPA did not refer to the original IPCC projection in 

either its TSD or in the Administrator’s Endangerment 

Finding. It does not impact climate change science 

findings or have any meaningful implication for the issue 

of endangerment in the United States. Furthermore, Volume 

2, section 2.1.3 of the RTP document shows that EPA 

reviewed the entire discussion of glacial effects in IPCC 

AR4 and concludes that this single faulty projection does 

not compromise the IPCC’s overall assessment of observed 

glacier loss, projected glacier loss, and the impacts of 

glacier loss on water resources in the Himalayas. 

(iii) Characterization of Climate Change and Disaster 

Losses 

The Southeastern Legal Foundation asserts that the 

IPCC AR4 mischaracterized the findings of a study on 

climate change and historic disaster losses. EPA addresses 

the specific study at issue in Volume 2, section 2.1.4 of 

the RTP document and provides its more general response to 

this study and this issue here. 

First, EPA never cited or relied on the study at issue 

in its TSD. EPA did not discuss the link between climate 

change and the historic trends in the economic magnitude of 

disaster losses in the TSD. To support the Endangerment 
Page 119 of 217

Finding, EPA cited the potential future impacts of climate 

change on the number and severity of extreme weather 

events, for which the Southeastern Legal Foundation levels 

no criticism. There are many different factors influencing 

the economic losses from a disaster, making it difficult to 

determine the impact of climate change from historic data 

on trends in economic disaster loss. Therefore, contrary 

to petitioners’ claims, EPA did not rely on historic trends 

of economic disaster losses (the subject of the study at 

issue) to evaluate the likelihood that climate change would 

lead to an increase in the number or frequency of such 

weather events. EPA instead focused on the physical and 

environmental (not the economic) impacts associated with 

climate change. The Administrator’s Endangerment Finding 

was clear that it was more forward-looking on this issue, 

stating: 

The evidence concerning how human-induced climate 

change may alter extreme weather events also clearly 

supports a finding of endangerment, given the serious 

adverse impacts that can result from such events and 

the increase in risk, even if small, of the occurrence 

and intensity of events such as hurricanes and floods. 

(74 FR 66526) 

Furthermore, EPA’s review of the particular study at 

issue in Volume 2, section 2.1.4 of the RTP document shows 

that IPCC did not mischaracterize this study (e.g., IPCC 

included the appropriate caveats that were also stated in 
Page 120 of 217

the underlying study), and that there were valid reasons 

for IPCC to use the study (e.g., as the most recent study 

of its kind at the time). 

(iv) Validity of Alps, Andes, and African Mountain 

Snow Impacts 

Several petitioners argue that IPCC claims of glacier 

melt in the Andes, the Alps, and parts of Africa arise from 

a magazine article and a Master’s thesis, and thus should 

not be viewed as credible. This particular issue is 

addressed in Volume 2, section 2.1.5 of the RTP document, 

and EPA’s response is summarized here. 

First, the extent to which snow and glaciers in the 

Andes, Alps and parts of Arica are melting or are projected 

to melt is an issue that is tangential to the 

Administrator’s decision that public health and welfare are 

endangered within the United States. Second, the 

petitioners mischaracterize these references within IPCC 

AR4, as these are actually references to “loss of ice 

climbs,” not reductions in mountain glaciers. Loss of ice 

climbs is an indicator of warming over ice-covered areas. 

EPA acknowledges that these references come from gray 

literature but these citations are appropriate and within 

the IPCC’s guidelines for use of gray literature. They 

provide additional evidence consistent with the peer-
Page 121 of 217

review-supported conclusion that in most places snowpack is 

declining and glaciers are melting worldwide. Furthermore, 

EPA did not rely on these references or refer to “loss of 

ice climbs” as an indicator of climate change. 

(v) Validity of Amazon Rainforest Dieback Projection 

Petitioners challenge the IPCC’s statement that “[U]p 

to 40 percent of the Amazonian forests could react 

drastically to even a slight reduction in precipitation,” 

alleging that it is unsubstantiated gray literature. EPA 

reviews this issue in Volume 2, section 2.1.6 of the RTP 

document and provides its general response here. 

The IPCC AR4 statement in question about the Amazon 

appears to have been inadequately referenced but the 

content of the statement is correct according to the 

underlying literature. For this statement, the IPCC did 

cite gray literature35, which itself cited a peer-reviewed 

study36 and relied on other peer-reviewed literature. It is 

worth noting that a newspaper that originally reported this 

alleged problem with the IPCC’s representation of this 

Amazon issue recently reversed itself and printed a 

 

35 Rowell, A. and P.F. Moore (2000). Global Review of Forest Fires. 

World Wildlife Federation and The World Conservation Union.. available 

at: http://data.iucn.org/dbtw-wpd/edocs/2000-047.pdf. (last accessed 

April 12, 2010). 

36 Nepstad, D. C., et al. (1999). Large-scale impoverishment of 

Amazonian forests by logging and fire. Nature 398:505-508. 
Page 122 of 217

correction on June 20, 2010.37 Morever, this issue is not 

discussed in the TSD and is of no relevance to the 

Findings. 

(vi) Validity of African Rain-Fed Agriculture 

Projection 

Some petitioners object that a statement in EPA’s TSD 

based on a statement in IPCC AR4 concerning reduction of 

yields from rain-fed agriculture in some countries in Africa 

was from gray literature and is therefore not credible. EPA 

reviews this issue in Volume 2, section 2.1.7 of the RTP 

document and provides its general response here. 

There is no evidence that the IPCC statement in 

question regarding African rain-fed agricultural yields is 

not credible, based on the underlying studies, nor is there 

any evidence that IPCC authors acted inappropriately by 

citing the material on which this statement is based. The 

IPCC statement cites a report38 published by the 

International Institute for Sustainable Development funded 

by Canada, U.S. AID, and other public and private 

institutions. The percent reduction number was obtained 

 

37 Sunday Times correction. 

http://www.thesundaytimes.co.uk/sto/news/uk_news/Environment/article322

890.ece. 

38 Agoumi, A. (2003). Vulnerability of North African Countries to 

Climatic Changes. International Institute for Sustainable Development 

and the Climate Change Knowledge Network. (2003). Available at: 

http://www.cckn.net//pdf/north_africa.pdf. Accessed April 12, 2010. 
Page 123 of 217

from vulnerability studies prepared under the UN 

Environmental Programme Global Environment Fund and 

National Communications of three African countries to the 

UNFCCC. This study was included due to the paucity of 

peer-reviewed material relating to some parts of the world, 

particularly Africa. This is consistent with the IPCC’s 

guidance on the use of gray literature. Furthermore, the 

statement relates to impacts outside the United States, and 

it did not materially impact the Administrator’s 

determination of endangerment of public health and welfare 

in the United States. 

b. Response to Claims That the IPCC Has a Policy 

Agenda and is Not Objective and Impartial 

Several petitioners raise various arguments to support 

their allegation that IPCC AR4 is advancing a policy agenda 

and is not an objective and impartial scientific body, thus 

questioning EPA’s use of IPCC AR4 as a significant 

reference document to support the Administrator’s Findings. 

EPA reviews and responds to each of these claims in 

Volume 2, section 2.2 of the RTP document, and provides the 

more general responses here. EPA also previously responded 

to public comments about IPCC’s report development 

procedures in the RTC document (see Volume 1, section 1 and 

Appendix A, “IPCC Principles and Procedures”). 
Page 124 of 217

The petitioners submit four objections along with 

excerpts from the CRU e-mails related to: 1) authorship and 

reviewer roles among IPCC personnel; 2) a CRU e-mail 

allegedly showing that IPCC authors were aware that citing 

their own papers could be seen as using the IPCC process to 

advance their own views rather than to present a neutral 

overview of the science; 3) allegations that the IPCC is a 

biased organization, including claims that IPCC lead 

authors encouraged other authors to focus on policyprescriptive science; and 4) allegations that IPCC authors 

forced consensus and altered the contents of the assessment 

reports to eliminate any suggestion of non-consensus. 

After reviewing the petitioners’ arguments, EPA finds 

that the evidence and arguments provided by petitioners do 

not support their serious allegation that the peer-review 

and assessment report processes employed by the IPCC were 

“fundamentally corrupt” and policy prescriptive. The 

petitioners’ arguments, which heavily rely on the selective 

use and narrow reading of CRU e-mails, as well as some 

newspaper articles, do not demonstrate that the IPCC peerreview and report development processes were inadequately 

designed or that they were not properly implemented. These 

allegations by the petitioners are devoid of any scientific 

evidence or scientific argument that would cause EPA to 
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find that the key conclusions of IPCC AR4 are inaccurate or 

that they do not appropriately reflect the degree of 

scientific consensus on the scientific issues germane to 

the Administrator’s Endangerment Finding. Therefore, 

petitioners’ evidence and arguments do not support changing 

EPA’s position, as stated in the Endangerment Finding, that 

the assessment literature, including IPCC AR4, represents 

the “best reference materials for determining the general 

state of knowledge on the scientific and technical issues 

before the agency in making an endangerment decision.” 

Volume 2, section 2.2.3.1 of the RTP document, for 

example, demonstrates that, contrary to petitioners’ 

assertions, a few scientists that were not named as 

contributing authors for Chapter 6 of IPCC AR4, Working 

Group I39 did not contribute significantly to the writing 

and editorial decisions of that chapter. Given their every 

limited role in the chapter (e.g., providing input on a 

single figure), it is entirely reasonable that they were 

not named contributing authors, who are charged with 

writing parts of the report. Therefore, EPA finds that 

there is no basis for the claim that IPCC reviewer and 

author procedures were circumvented. EPA’s review of this 

issue is consistent with the finding of the Independent 

 

39 Jansen et al., 2007 
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Climate Change E-mails Review 40 which stated, among other 

things, that “There is no proscription in the IPCC rules to 

prevent the author team seeking expert advice when and 

where needed.” 

Petitioners appear concerned about the contributing 

author designation because these few scientists were expert 

reviewers of the IPCC AR4, and the petitioners believe that 

the act of providing even a limited amount of information, 

in addition to their reviewer roles, would have given them 

undo power to shape the report. This argument is baseless. 

EPA notes that although the expert review comments are 

available to the public41, petitioners did not provide a 

single example from the comments of these individuals to 

support their claim of undo influence or abuse of their 

purported “power” over IPCC AR4 conclusions. 

Volume 2, section 2.2.3.2 of the RTP document examines 

the allegation by petitioners that the frequency with which 

IPCC authors cite their own studies should be viewed as 

unacceptable and seen as evidence that IPCC AR4 lacks 

objectivity. First, it should come as no surprise that for 

some of these fairly specialized fields of climate change 

 

40 Russell, 2010 41 Reviewer comments and author responses for draft chapters of IPCC AR4 

Working Group I and II volumes (the primary volumes at issue for the 

Endangerment Finding) are publically available at the following 

websites, respectively: http://hcl.harvard.edu/collections/ipcc/ and 

http://ipcc-wg2.gov/publications/AR4/ar4review.html 
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science authors who publish the most on these topics would 

in turn be selected by IPCC to author chapters on those 

same topics. EPA finds the frequency with which IPCC 

authors cite their own peer-reviewed studies to be entirely 

acceptable and reasonable. Again, petitioners completely 

fail to show why this underlying cited literature itself is 

flawed or why the IPCC AR4 conclusions, based on this 

underlying literature, are flawed. Importantly, one of the 

CRU e-mails that petititioners use as purported evidence of 

IPCC authors engaged in foulplay to cite their own work 

actually shows an IPCC coordinating lead author explicitly 

encouraging his IPCC co-authors to minimize citations to 

their own work, and to do so only “unless they are 

absolutely needed.” 

Volume 2, section 2.2.3.3 of the RTP document examines 

the petitioners’ assertion that IPCC is biased and that 

IPCC authors worked to produce policy-prescriptive science 

and to reach preconceived conclusions. Here too, the 

petitioners do not address any of the IPCC AR4 science 

directly. Rather, petitioners refer to a selection of CRU 

e-mails by IPCC authors who wrote to other IPCC co-authors 

to urge them, for example, to focus on “policy relevant” 

science. First, “policy relevant” by no means implies 

“policy prescriptive” or scientifically biased. It is, in 
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fact, policy informative and neutral, in direct contrast to 

the goal of policy prescriptive statements. Second, 

petitioners do not identify how specific information in 

IPCC AR4 should be considered biased as a result of the 

private e-mail exchanges. Petitioners do not highlight the 

specific statements in the IPCC AR4 that are supposedly 

“policy prescriptive,” never explain what policy agenda was 

being advanced, and never describe how the CRU e-mails 

support their claim that the science was actually 

manipulated in service of this unspecified agenda. The 

IPCC’s own guidelines42 state that its mission is to produce 

information that is “policy relevant and policy neutral, 

never policy prescriptive.” There is no evidence provided 

by petitioners that IPCC authors deviated from this 

practice. 

In another example in Volume 2, section 2.2.3.3 of the 

RTP document, petitioners claim that a CRU e-mail exchange 

demonstrates that IPCC authors were colluding to make a 

strong case about a certain scientific conclusion rather 

than working to produce neutral science. EPA’s review 

shows that there is no support for this claim. EPA’s 

review shows that the CRU e-mails, in their full context, 

speak for themselves and simply show a small group of 

 

42 IPCC, 2010c. 
Page 129 of 217

scientists working on various alternative ways to present a 

figure that was comprehensive and offered key contextual 

information on temperature trends over the past several 

centuries. Petitioners do not show that these alternatives 

– which are discussed in the e-mails – are biased, or 

explain why the option that was selected is not “neutral”. 

If fact, the e-mail record shows that the alternative 

selected was the most comprehensive and transparent of the 

options. 

In Volume 2, section 2.2.3.4 of the RTP document, EPA 

reviews petitioners’ claim that certain IPCC authors kept 

out some studies with the goal of hiding any non-consensus 

on key issues. The CRU e-mail exchanges among some IPCC 

authors are the only pieces of evidence offered by 

petitioners to support this allegation. EPA’s review of 

this issue demonstrates that the CRU e-mails simply do not 

show that the contents of the IPCC chapter in question, let 

alone the contents of the entire IPCC AR4, were altered to 

eliminate a suggestion of non-consensus, or IPCC authors 

actively tried to suppress (or were successful in 

suppressing) external challenges to consensus. It is not 

uncommon for scientists to critique the work of others, and 

the e-mails do not provide evidence that the IPCC authors 

acted unethically. Section 2.2.3.4 of the RTP document 
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also addresses the now oft-cited e-mail where an IPCC 

author states, “I tried hard to balance the needs of the 

science and the IPCC, which were not always the same.” 

Petitioners claim this e-mail demonstrates a biased IPCC 

process. A simple reading of the entire e-mail exchange 

reveals a different story. In fact, this IPCC author gets 

complimented from another for his objectivity and evenhandedness in handling the challenges of working on IPCC 

AR4. This IPCC author also expressed frustration with the 

time spent away from doing new science, which is not the 

primary job of an IPCC chapter author or of the IPCC in 

general; the primary role of the IPCC is to assess existing 

science already published in the literature, i.e., in this 

author’s words, “the needs of the science and the IPCC” are 

not always the same. In context, it is clear that the 

needs of the IPCC in this case are the requirements of 

doing assessments of existing literature rather than 

producing “original and substantive” work. EPA’s review 

demonstrates that when the e-mails are read in their full 

context, it is clear that the authors of these e-mails 

sought to convey the science accurately and address 

disagreements in a fair and even-handed way. Again, 

petitioners have selectively picked excerpts from these emails to make assertions attacking the underlying science 
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of the Endangerment Finding, but these assertions simply 

have no support. 

3. Process and Other Issues Raised by the Petitioners

The process and other issues raised by the petitioners 

include claims that a) the USGCRP and the NRC are not 

separate and independent assessments from IPCC; b) EPA’s 

process to develop the scientific support for the Findings 

is flawed; c) there are improper peer-review processes in 

the underlying scientific literature used by the major 

assessments; and d) certain scientists did not adhere to 

Freedom of Information Act requests. Each of these issues 

is addressed below and in more detail in Volume 3 of the 

RTP document. 

a. Claims That the Assessments by the USGCRP and NRC 

Are Not Separate and Independent Assessments 

Two petitioners argue that the assessment reports upon 

which EPA relied are not from three separate, independent 

groups. They claim that the USGCRP and NRC assessment 

reports are not separate and independent because they are 

based on the findings of IPCC AR4. Petitioners claim the 

USGCRP and NRC reports regularly cite and rely on data, 

resources, and conclusions in the IPCC reports, 

contradicting arguments that all three of the assessments 

are separate and independent. The petitioners argue that 
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because of this the USGCRP and NRC assessments must be 

flawed in the same way that IPCC AR4 is purported to be 

flawed by the petitioners. Volume 3, section 3.2 of the 

RTP document addresses this claim and EPA summarizes its 

response here. 

EPA finds no merit to this argument. The 

organizational and personnel differences, and the detailed 

and robust report development procedures employed by the 

IPCC, USGCRP, and NRC demonstrate that these assessment 

reports are separate and independent. Petitioners’ claims 

to the contrary are insufficient and unsubstantiated. 

The similarity of the conclusions among the assessment 

reports from the three bodies, for example, provides 

evidence of the strength of the science in that it 

consistently points different scientific reviewers in the 

same direction. The fact that each of these bodies 

referenced many of the same studies and IPCC AR4 or arrived 

at consistent conclusions is not evidence that these 

reports are not independent assessments of the available 

science related to climate change. The test of separation 

and independence is not whether an assessment reaches a 

different result or conclusion, it is whether independent 

discretion and judgment were exercised. To assert, as the 

petitioners do, that consistency of results represents a 
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weakness rather than a strength of the underlying science 

is an unwarranted argument that assumes fundamental flaws 

in the IPCC and a resulting grand ripple effect across all 

the major assessments used by EPA. EPA discusses above and 

further demonstrates throughout the RTP document 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, including the IPCC 

AR4 conclusions and its underlying studies, and therefore 

EPA rejects the premise of this argument. 

Furthermore, the USGCRP, the IPCC, and NRC have their 

own, separate report development procedures. These 

separate processes have already been described in the TSD 

and in the RTC document, Volume 1. The differences in the 

organizations, the groups of scientists who developed the 

assessments, and scope of the assessments produced by each 

body is discussed in detail in Volume 1 of the RTC 

document. 

 The IPCC, created in 1988 by the United Nations 

Environment Programme and the World Meteorological 

Organization (WMO), is open to all member countries of 

the United Nations and the WMO. At regular intervals, 

the IPCC prepares comprehensive assessments of 

scientific, technical, and socio-economic information 

relevant for the understanding of human induced 

climate change, potential impacts of climate change, 

and options for mitigation and adaptation all at 

global and regional scales. The most recent 

assessment—the AR4—included thousands of scientists 
Page 134 of 217

from all over the world, who participated on a 

voluntary basis as authors, contributors, and 

reviewers (IPCC, 2007a). While many federal and 

nonfederal scientists from the United States were 

involved in the development of the AR4, the United 

States is just one of 194 countries that contribute to 

the assessments. 

 The USGCRP is part of the United States Executive 

Branch. Thirteen departments and agencies participate 

in the USGCRP, including EPA. A critical role of the 

interagency program is to coordinate research and 

integrate and synthesize information to achieve 

results that no single agency, or small group of 

agencies, could attain. Between 2004 and 2009, the 

USGCRP produced 21 synthesis and assessment reports on 

a wide range of topics (e.g., temperature trends in 

the lower atmosphere; weather and climate extremes in 

a changing climate; and the effects of climate change 

on agriculture, land resources, water resources, and 

biodiversity). The USGCRP assessment reports are 

developed to enhance understanding of natural and 

human-induced changes in the Earth’s global 

environmental system; to monitor, understand, and 

predict global change in the United States; and to 

provide a sound scientific basis for national and 

international decision-making. Each of these reports 

had a unique team of authors, drawn from relevant 

disciplines. Many authors were federal scientists, 

and in some cases, nonfederal scientists contributed 

their expertise to the process. While some of the 

USGCRP authors participated in the development of the 

IPCC AR4, most did not. 

 The NRC is an independent scientific organization that 

is not affiliated with either the IPCC or USGCRP. As 

described in Appendix C of Volume 1 of the RTC 

document, the NRC: 

enlist(s) the nation’s foremost scientists, 

engineers, health professionals, and other 

experts to address the scientific and technical 

aspects of society’s most pressing problems. 

Each year, more than 6,000 of these experts are 

selected to serve on hundreds of study committees 

that are convened to answer specific sets of 

questions. All serve without pay. Federal 

agencies are the primary financial sponsors of 
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the Academies’ work. Additional studies are 

funded by state agencies, foundations, other 

private sponsors, and the National Academies 

endowment. The Academies provide independent 

advice; the external sponsors have no control 

over the conduct of a study once the statement of 

task and budget are finalized. Study committees 

gather information from many sources in public 

meetings but they carry out their deliberations 

in private in order to avoid political, special 

interest, and sponsor influence. 

Ten NRC reports are cited in the Endangerment Finding 

and TSD. Each of these reports has a unique author 

committee, selected based on their areas of expertise. 

While some of the NRC study committee members have 

participated in either the IPCC or USGCRP report 

development processes, many have not. 

The USGCRP and NRC reports on which EPA relied were 

the result of an objective review and assessment of the 

scientific literature available at the time of their 

development (including any previously published 

assessments), related to the effects of greenhouse gas 

emissions on the climate system and the impacts of these 

changes on ecosystems and society. The organizations 

conducting the reviews were distinct and separate, and 

neither organization had control or supervision over the 

other. The groups of scientists involved in the reviews 

overlapped to some degree, but significant numbers of 

scientists were involved with one but not other reports. 

In all cases, personnel at NRC who supervised the review 
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and preparation of the final reports were different from 

those who performed these functions for USGCRP. 

Like the IPCC, the USCGRP and NRC provide public 

opportunities to provide input and comment during report 

development (see RTC document, Volume 1). In addition, the 

NRC reports undergo a rigorous, independent external review 

by experts whose comments are provided anonymously to the 

committee members. 

Separate and apart from the issue of the independence 

of these assessment reports, the petitioners provide no 

information to demonstrate that the key scientific 

conclusions of the IPCC, USGCRP, and NRC are wrong or that 

EPA erred in relying upon them. The specific science 

issues raised by petitioners are discussed throughout this 

Decision and in the RTP document. Thus, whether or not the 

various assessment reports are separate and independent, 

EPA reasonably relied upon them as reflecting the current 

state of the science and the degree of broad consensus 

within the science community on these issues. 

Bolstering the case that the IPCC, USGCRP and NRC 

assessments available at the time of the final Endangerment 

Finding in December 2009 were robust and appropriate for 

EPA to use, the May 2010 assessment of the NRC, “Advancing 

the Science of Climate Change,” states that its major 
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scientific conclusion is “consistent with the conclusions” 

of those previous assessments. Note also that this May 

2010 NRC assessment was able to incorporate scientific 

literature published since EPA completed its scientific 

record to finalize the 2009 Endangerment Finding. 

b. Approaches and Processes Used to Develop the 

Scientific Support for the Findings 

Several petitioners object to the process and approach 

EPA used in developing the scientific support for the 

Endangerment Finding. One of these specific arguments is 

new whereby the petitioners allege that EPA ignored public 

concerns about the implications of the e-mails involving 

scientists at the CRU, and instead “plowed ahead with 

compromised data, undermining its core conclusions in the 

process.” EPA discusses and responds to this issue in 

section (i) below and in section 3.1.2 of the RTP document. 

The petitioners also raise issues that EPA already 

responded to in Volume 1 of the RTC document. Some of the 

concerns submitted are supported with ‘new information’ and 

some are not. In (ii) below, EPA summarizes the response 

to the claim that EPA did not independently judge the 

underlying science, and in (iii) below EPA concludes that 

the Agency did not violate the Information Quality Act 

(IQA, or the Data Quality Act), as alleged by petitioners. 
Page 138 of 217

Section 3.1.3 of the RTP document more fully responds to 

these three allegations and other related concerns raised 

by the petitioners regarding the process and approach EPA 

used in developing the scientific support for the 

Endangerment Finding. 

(i) Issues Regarding Consideration of the CRU E-mails 

The sole new argument raised by petitioners regarding 

the approach and process EPA used into develop the Findings 

is that EPA ignored public concerns about the implications 

of the e-mails involving scientists at CRU, and instead 

“plowed ahead with compromised data, undermining its core 

conclusions in the process.” EPA responds to this issue in 

Volume 3, section 3.1.2 of the RTP document and summarizes 

its response here. 

Prior to finalizing the Endangerment Finding, EPA 

carefully reviewed many of the CRU e-mails, and determined 

that many of the issues raised therein had also been raised 

through the public comments on the proposed Findings. EPA 

reviewed the underlying scientific issues that were 

presented to EPA at the time (see, for example, RTC Volume 

2). Based on that initial review, EPA concluded that the 

fundamental conclusions of the assessment literature 

remained sound as to the state of the science on greenhouse 

gases and climate change. EPA did not inappropriately 
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“plow ahead;” EPA assessed the issues raised by commenters 

and the CRU e-mails in light of our comprehensive review of 

climate science and all of the objections to the science 

raised by commenters, and concluded that our review of the 

science and the conclusions based on it were sound. 

Petitioners have now raised more specific concerns 

with respect to the CRU e-mails. EPA has reviewed all of 

the CRU e-mails, and our responses to the particular 

science issues raised by petitioners in light of these emails are provided in other sections of this Decision and 

in the RTP document. As discussed there, petitioners have 

routinely misunderstood or mischaracterized the scientific 

issues, drawn faulty scientific conclusions, resorted to 

hyperbole, impugned the ethics of climate scientists in 

general, characterized actions as “falsification” and 

“manipulation” with no basis or support, and placed an 

inordinate reliance on blogs, news stories, and literature 

that is often neither peer reviewed nor accurately 

summarized in their petitions. Petitioners often “cherrypick” language that creates the suggestion or appearance of 

impropriety, without looking deeper into the issues or 

providing corroborating evidence that improper action 

actually occurred. 
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(ii) Claims that EPA Did Not Independently Judge the 

Underlying Science

Several petitioners argue that the Administrator did 

not independently judge the primary scientific literature 

and data. Instead, they claim that she improperly relied 

on summary scientific reports produced by third parties or 

“foreign entities.” This is not a new issue brought to 

EPA, but was raised and addressed during the public comment 

period. Section III.A of the Findings responds to comments 

that EPA should have conducted its own independent 

assessment of the primary scientific literature and not 

relied on scientific reports produced by third parties such 

as the USGCRP, NRC or IPCC. See also Volume 1 of RTC 

document, particularly Response 1-1. 

It is useful to describe the process EPA followed in 

exercising its scientific judgment in making the 

Endangerment Finding. EPA did not passively and 

uncritically accept a scientific judgment and finding of 

endangerment supplied to it by outsiders. Instead, EPA 

evaluated all of the scientific information before it, 

determined the current state of the science on greenhouse 

gases, the extent to which they cause climate change, how 

climate change can impact public health and public welfare, 

and the degree of scientific consensus on this science. 
Page 141 of 217

EPA applied this science to the legal criteria for 

determining endangerment, i.e., whether greenhouses gases 

cause, or contribute to, air pollution that may reasonably 

be anticipated to endanger public health or welfare. EPA 

did this after presenting its scientific views before the 

public for comment and evaluating and considering all 

comments received, as well as documenting responses to all 

significant public comments (see volumes 1-11 of the RTC 

document). EPA properly and carefully exercised its own 

judgment in all matters related to the Endangerment 

Finding. 

The core of petitioners’ objection is that they do not 

agree with important parts of the scientific information 

upon which EPA relied. They frame this as a failure of EPA 

to exercise its own judgment, or as EPA ceding to an 

outside body its responsibility to exercise independent 

judgment. It is clear from the record for the Findings 

that EPA exercised its own judgment and did not cede its 

authority or judgment to anyone. The fact that petitioners 

disagree with the information EPA relied upon and EPA’s 

conclusions is not evidence of a lack of exercise of 

discretion or judgment. 

EPA relied on the existing assessment reports of the 

USGCRP, IPCC, and NRC as a primary source for determining 
Page 142 of 217

the current state of the science relating to greenhouse 

gases and climate change, and for determining the degree of 

scientific consensus on these issues. EPA’s view then and 

now is that these assessment reports represent the best 

primary references to provide the scientific underpinnings 

to inform the Administrator’s judgment regarding 

endangerment. These assessment reports provide exactly the 

kind of information that is required, i.e., they 

demonstrate how greenhouse gases are affecting the climate 

now, are projected to affect climate in the future, and how 

these current and projected climate changes impact public 

health and welfare. These assessment reports also bring 

together and synthesize the numerous individual studies in 

the scientific literature to draw overarching conclusions 

about the state of the science. Finally, each of these 

assessment reports go through rigorous and transparent 

peer-review processes, such that the conclusions carry 

significant weight in a way that is typically not possible 

for one individual study in a scientific journal. EPA’s 

review of the objections raised by petitioners to the 

process and the substance of the various assessment reports 

does not support changing this view. 

The petitioners appear to imply that EPA would have 

drawn different conclusions had it conducted its own 
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separate assessment. After examining the breadth and 

quality of the USGCRP, IPCC, and NRC assessments, EPA 

disagrees. These reports already reflect the body of 

underlying scientific literature that EPA itself would have 

had to synthesize had it decided to conduct yet another 

assessment, independent from USGCRP, IPCC and NRC. These 

assessments have been reviewed and formally accepted by, 

commissioned by, and in some cases authored by U.S. 

government agencies and individual government scientists. 

By relying on the assessment literature, EPA is benefitting 

from the confidence and strength of an entire federal 

research enterprise. There is no reason to think that 

these assessments do not represent the best primary source 

material to determine the state of science on the relevant 

issues. 

Petitioners disagree with some of the conclusions of 

the assessment literature and believe that not all 

scientific points of view were fully considered therein. 

However, there was a robust public comment process on EPA’s 

proposed Endangerment Finding, which provided an 

opportunity for the public to evaluate and comment on EPA’s 

preliminary scientific conclusions. Many commenters 

provided literature and/or arguments to support their views 

and EPA reviewed such literature and arguments in the 
Page 144 of 217

Agency’s responses. EPA’s final judgment was based on 

EPA’s evaluation of both the assessment literature and the 

additional information and views provided through public 

comment. EPA has no reason to believe that putting this 

significant body of work aside and attempting to develop a 

new and separate assessment would provide any better 

scientific basis for making the endangerment decision. 

(iii) Claims that EPA Violated the Information Quality 

Act 

EPA already provided a detailed response to arguments 

of alleged IQA violations in RTC Volume 1. The petitioners 

now make essentially the same general argument that EPA’s 

use of third-party assessment reports violates the IQA. 

EPA notes that the petitioners are re-raising this issue in 

the petitions for reconsideration because they believe that 

the CRU e-mails show that “IPCC authors deleted information 

and hid behind foreign laws to avoid disclosure of key 

data” and that EPA would not have been able to obtain the 

data anyway. EPA responds to allegations involving the 

behavior of CRU scientists, including the allegation that 

data was destroyed, in (c) below, Volume 1 of the RTP 

document and Sections 3.3 and 3.4 of the RTP document. As 

stated in these sections, the evidence submitted by the 

petitioners in the form of the CRU e-mails does not support 
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their allegation that data were destroyed. Therefore, the 

“new” information presented by the petitioners does not 

call into question the overall integrity of the science, 

nor does it call into question the process EPA used in 

developing the Findings. As noted in RTC Volume 1, the IQA 

requires that an agency issue guidelines regarding data 

quality and ensure their implementation. EPA complied with 

the IQA by issuing its Guidelines for Ensuring and 

Maximizing the Quality, Objectivity, Utility and Integrity 

of Information Disseminated by the Environmental Protection 

Agency (U.S. EPA, 2002)43 and has acted consistently with 

these guidelines in developing the Findings. As stated in 

RTC Volume 1, EPA’s use of the assessment literature “is 

consistent with these guidelines because we thoroughly 

reviewed and evaluated the author selection, report 

preparation, expert review, public review, information 

quality, and approval procedures of IPCC, USGCRP/CCSP, and 

NRC to ensure the information adhered to a basic standard 

of quality, including objectivity, utility, and integrity.” 

The CRU e-mails cited by the petitioners do not 

undermine this view. EPA’s responses on the science issues 

raised by petitioners concerning these e-mails are 

 

43 U.S. EPA (2002). Guidelines for Ensuring and Maximizing the Quality, 

Objectivity, Utility, and Integrity of Information Disseminated by the 

Environmental Protection Agency. Washington, DC: U.S. Environmental 

Protection Agency. EPA/260/R-02/008. 
Page 146 of 217

discussed in detail in several other sections of this 

Decision as well as in the RTP document. As our detailed 

responses show, petitioners’ science-based claims do not 

support the conclusion that the IPCC or other assessment 

reports were biased, inaccurate, or scientifically 

incorrect. 

c. Freedom of Information Act Issues 

Several petitioners claim that the CRU e-mails provide 

evidence that leading climate scientists deliberately 

withheld key data and computer codes and attempted to 

obstruct or avoid UK Freedom of Information (FOI) and U.S. 

Freedom of Information Act (FOIA) requests from “climate 

skeptics.” These claims are addressed in Volume 3, section 

3.4 of the RTP document and EPA’s response is summarized 

here. 

 EPA’s review of the CRU e-mails indicates that in many 

cases, the data at issue were in fact released by the 

scientists, including data concerning a human “fingerprint” 

in the tropics, data underlying the HadCRUT temperature 

record, and data concerning historic temperature 

reconstructions. In addition, significant data were 

publicly available. Petitioners have not explained or 

shown why the amount of data and other information that was 

available was not adequate for researchers to replicate or 
Page 147 of 217

otherwise evaluate key findings, or to conduct other 

research. In addition, there was a robust and public 

process to submit, review, and publicly respond to comments 

on the scientific issues involved in all parts of the IPCC 

AR4. Petitioners do not rely on science or science based 

arguments to support their claim that the assessment report 

resulting from this robust process should not be relied 

upon by EPA. Instead, they rely on unsupported conclusions 

drawn from e-mails concerning a FOI request for personal 

communications between various scientists, where it appears 

that the appropriate University FOI officers had determined 

that these e-mails were exempt from release. This evidence 

does not support petitioners’ claims that the IPCC AR4 

should not be considered as part of the scientific basis 

for the Endangerment Finding. 

 EPA agrees with the results of the various 

investigations, which found that the scientists at issue 

conducted their research with scientific integrity and 

rigor, the research utilized methods which are fair and 

satisfactory, and that their actions were consistent with 

the common practice in climate research at that time. EPA 

also agrees with the recommendations of the Independent 

Climate Change E-mails Review supporting greater 

transparency in the future in this area of climate 
Page 148 of 217

research. Petitioners' evidence, however, does not support 

their conclusions that the research produced by these 

scientists was suspect, flawed, or biased, or that IPCC AR4 

or other assessment reports were suspect, flawed, or 

biased. Their evidence does not support the conclusion 

that the science at issue should not be relied upon by EPA. 

EPA has reviewed the petitioners’ claims and the emails and finds that in many cases, the petitioners make 

overly broad generalizations based on suggestions of 

inappropriate actions that are not supported by the 

evidence provided by the petitioners. Regarding the quote 

from the UK Information Commissioner’s Office, the recent 

inquiry by the UK House of Commons Science and Technology 

Committee (2010)44 concluded that this statement was the 

personal opinion of the Deputy Information Commissioner and 

was not based on the results of a formal government 

investigation. 

EPA finds that most of the language in the CRU e-mails 

that petitioners allege shows impropriety is taken out of 

context. Petitioners do not provide corroborating evidence 

that improper action actually occurred, let alone evidence 

that any alleged improper action led to biased or 

 

44 UK Parliamentary (2010). House of Commons, Science and Technology 

Memoranda. Available at: 

http://www.publications.parliament.uk/pa/cm200910/cmselect/cmsctech/mem

o/climatedata/contents.htm. 
Page 149 of 217

inaccurate science that was ultimately used by EPA to 

support the Findings. Based on our review of the e-mails, 

the authors were dismayed at what they viewed as frivolous 

requests that were wasting their time, not that the 

requestors were going to uncover “fraud” or “wrongdoing” 

with regard to their research, as has been alleged by the 

petitioners. 

EPA finds from its review that the e-mail authors 

expressed significant frustration at repeated requests for 

specific explanations and computer codes when the basic 

data had already been made available and the methodology 

for replicating particular studies had already been 

published in the literature. This type of approach was 

considered to be common practice at the time, as the UK 

House of Commons Science and Technology Committee (2010)45

also found in their analysis of the CRU e-mails: “In the 

context of the sharing of data and methodologies, we 

consider that Professor Jones’s actions were in line with 

common practice in the climate science community. It is 

not standard practice in climate science to publish the raw 

data and the computer code in academic papers.” EPA finds 

that the petitioners’ evidence does not provide a basis to 

 

45 UK Parliamentary (2010). House of Commons, Science and Technology 

Memoranda. Available at: 

http://www.publications.parliament.uk/pa/cm200910/cmselect/cmsctech/mem

o/climatedata/contents.htm. 
Page 150 of 217

question the scientific integrity or conclusions of the 

climate change research conducted by CRU researchers. 

d. Integrity of Peer-Reviewed Literature 

Several petitioners claim that the CRU e-mails provide 

evidence that leading climate scientists engaged in actions 

to suppress dissenting views about anthropogenic global 

warming. Specifically, petitioners claim that these 

scientists unfairly gave favorable reviews of each other’s 

manuscripts while providing negative reviews of manuscripts 

authored by “climate skeptics,” made efforts to unfairly 

expedite publication of their responses to papers by 

“climate skeptics,” conspired to remove editors of 

prominent journals that had published dissenting views of 

climate change, and boycotted the journals in reprisal. 

The petitioners argue that the cumulative effect of these 

alleged actions with regard to peer-reviewed literature has 

been to create an artificial consensus about anthropogenic 

climate change that has “tainted [climate change 

literature] in favor of desired papers.” Some petitioners 

conclude that EPA has lost the basis for its Findings 

because the Agency assumed a “legitimate, objective 

‘consensus’ regarding anthropogenic global warming” existed 

among scientists and disregarded any contrary views or 
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contrary evidence. EPA responds to these claims in Volume 

3, section 3.3 and summarizes its response here. 

Petitioners’ claims are not based on scientific 

analysis or arguments, and their evidence does not support 

changing or revising EPA’s use of the major assessments of 

peer-reviewed literature or the overall scientific 

conclusions about climate change reached from the thousands 

of papers considered in the assessments. The objections 

raised by the petitioners have not called into question or 

changed EPA’s conclusion that the science supporting the 

Endangerment Findings is robust, compelling, and has been 

appropriately characterized by EPA. 

EPA disagrees with the petitioners’ argument that the 

Findings were based on a false consensus regarding 

anthropogenic climate change, and that EPA disregarded 

contrary views or evidence including those not represented 

in the peer-reviewed literature. For reasons stated 

throughout this Decision and section 3.3 of the RTP 

document, EPA’s view is that the state of the science has 

been carefully and appropriately characterized by EPA and 

properly interpreted by the Administrator in the 

Endangerment Finding. 

Many diverging viewpoints and a variety of findings 

are represented in the scientific literature on climate 
Page 152 of 217

change. The assessment reports routinely identified the 

degree of certainty around any conclusion and recognized 

the existence of ongoing debate within the scientific 

community on all of these issues, as is the norm in all 

science endeavors. The Administrator’s Endangerment 

Finding relied on a careful consideration of the full 

weight of scientific evidence and a thorough review of 

hundreds of thousands of public comments, which contained 

many different opinions and interpretations of the science. 

Therefore, to claim, as the petitioners do, that these emails demonstrate that EPA did not take into account any 

dissenting views on the subject of climate change science 

is a gross mischaracterization of the total record that 

supports the Administrator’s Findings. 

The petitioners rely upon some CRU e-mails (typically 

taken out of context), a small number of papers, and both 

actual and alleged events regarding scientific journals to 

claim that leading climate scientists conspired to keep 

dissenting views of climate change out of the broad body of 

peer-reviewed literature and create an artificial consensus 

about anthropogenic climate change. In all cases presented 

by the petitioners it appears the scientists involved were 

making their scientific objections known, and were basing 

their objections on the science and not on assumptions or 
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speculation. The evidence presented by petitioners does 

not support their claims of bias, either for the specific 

papers and individuals at issue, or for the much broader 

and sweeping challenges made concerning the integrity of 

all peer-reviewed climate literature. 

For the few papers at issue, the petitioners do not 

argue based on scientific merits, and instead assume that 

the few papers they cite received unjustified unfavorable 

reviews and were unfairly rejected for publication without 

providing supporting evidence. Petitioners do not address 

the possibility that these papers were scientifically 

inadequate and that the scientists were justified in 

recommending that they not be published. EPA notes that 

there is no evidence presented beyond these few papers of 

the claimed general effort to manipulate the peer-reviewed 

journal publication process. 

The evidence provided by the petitioners also does not 

show that the scientists engaged in improper behavior or 

sabotage of the two journals that are discussed in the emails, or their editors, nor is there evidence to conclude 

that any action on the part of these scientists involved in 

the e-mail correspondence resulted in the replacement of 

the journal editors. Our review of the full discussion of 

the e-mails indicates, again, that petitioners have 
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exaggerated the significance of actual or purported events 

in an attempt to cast doubt on the underlying science and 

the processes relied upon to produce the science. 

F. Petitioners’ Arguments Do Not Meet the Standard For 

Reconsideration

As discussed above, petitioners must demonstrate that 

their objections are of central relevance to the outcome of 

the underlying decision, and must demonstrate either that 

it was impracticable to raise the objections during the 

public comment period or that the grounds for raising such 

objections arose after the close of the comment period (but 

within the time specified for judicial review). The above 

analysis shows that science-based and other objections 

discussed in this Section III and the accompanying support 

document are not of central relevance to the 

Administrator’s decision on endangerment and thus 

reconsideration is properly denied. 

An objection is of central relevance if it provides 

substantial support for the argument that the underlying 

decision should be revised. As shown above, none of the 

petitioners’ arguments related to climate science and data 

issues, issues raised by EPA’s use of IPCC AR4, and process 

issues provide substantial support for the argument that 

the Administrator’s Endangerment Finding should be revised. 
Page 155 of 217

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. 

Importantly, petitioners’ claims and the information they 

submit do not change or undermine our understanding of how 

human emissions of greenhouse gases cause climate change 

and how human-induced climate change generates risks and 

impacts to public health and welfare. 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. 

A petition for reconsideration cannot merely cite to 

new information and claim that is sufficient to require 

initiating a reconsideration process, attendant with the 

same procedures as the original decision. Mere allegations 

that information is of central relevance will not suffice. 

New information, even new information related to an agency 

decision, does not by itself warrant undermining the 

finality of agency decision making. To justify 

reconsideration a petitioner must show why the new 
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information demonstrates that the agency’s decision should 

be changed. 

Petitioners fail to do this. 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. Petitioners 

routinely take private e-mail communications out of context 

and assert they are “smoking gun” evidence of wrongdoing 

and scientific manipulation of data. In contrast, EPA’s 

careful examination of the e-mails and their full context 

shows that the petitioners’ claims are exaggerated 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 woefully inadequate pieces of 

evidence to challenge the voluminous and well documented 
Page 157 of 217

body of science that is the technical foundation of the 

Administrator’s Endangerment Finding. 

Petitioners’ objections that a limited number of 

factual mistakes now identified in the IPCC AR4, as well as 

other claimed mistakes, call into question the climate 

science supporting the Administrator’s Endangerment 

Finding, are similarly flawed. The two factual mistakes 

in IPCC AR4 confirmed by EPA’s review are tangential and 

minor and do not change the key IPCC AR4 conclusions that 

are central to the Administrator’s Endangerment Finding. 

Finally, as shown above, regarding objections based on 

allegedly new scientific studies and data, 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 where the 

petitioners have failed to acknowledge other new studies in 

making their arguments. Thus, petitioners have failed to 

demonstrate that their objections related to climate 

science and data issues, issues raised by EPA’s use of IPCC 

AR4, and process issues provide substantial support for the 
Page 158 of 217

argument that the Administrator’s decision on endangerment 

should be revised. 

Moreover, regarding many of their objections, 

petitioners also fail to demonstrate that it was 

impracticable to raise the objections during the public 

comment period or that the grounds for raising such 

objections arose after the close of the comment period (but 

within the time specified for judicial review). In many 

but not all cases EPA has identified instances where 

petitioners fail to base an objection on such new 

information. Given the volume of individualized comments 

and objections, EPA is identifying some of the types of 

situations where the objection, or grounds for the 

objection, raised by a petitioner does not satisfy this 

requirement for reconsideration. Several types of 

objections are premised on studies and other information 

that were available before the close of the comment period. 

In some cases petitioners basically repeat or raise the 

same arguments that were raised and responded to in the 

rulemaking. In other cases, petitioners raise allegedly 

new grounds, such as CRU e-mails, that they claim should 

cause EPA to reconsider a prior comment, or that justifies 

petitioners’ raising a new issue for the first time in the 

reconsideration petition. But as explained above and 
Page 159 of 217

throughout this Denial and supporting documents, the 

allegedly new information is not of central relevance, and 

therefore, EPA essentially is left with arguments that 

either were made previously during the comment period, or 

could have been raised during the comment period. Thus, 

many of the petitioners’ objections not only are not of 

central relevance, but they also fail to meet the temporal 

requirement for a petition for reconsideration. 

IV. Other Issues 

In this section, EPA responds to various objections to 

the Endangerment Finding based on concerns raised with 

respect to the impact of stationary source permitting 

requirements, the relationship of the Findings to NHTSA’s 

recent CAFE rule, the effects of the Findings and 

subsequent rulemakings on states and businesses, the need 

for a Formal Rulemaking Process, and EPA’s justification 

for its exercise of discretion in making the Endangerment 

Finding. 

A. The Tailoring Rule/Impacts of PSD and Title V 

Permitting Are Not Of Central Relevance to the Findings

Several petitioners raise objections based on EPA’s 

proposed rule to tailor the Prevention of Significant 

Deterioration (PSD) and title V permit programs for 

greenhouse gases. Proposed Prevention of Significant 
Page 160 of 217

Deterioration (PSD) and Title V Greenhouse Gas Tailoring 

Rule, 74 FR 55292 (Oct. 27, 2009) (Proposed Tailoring 

Rule).46 Specifically, petitioners argue that EPA’s 

statements in the Proposed Tailoring Rule demonstrate that 

the Findings are contrary to law and/or arbitrary and 

capricious. Because the Proposed Tailoring Rule was issued 

after the close of the comment period, but before the 

period for judicial review ran, petitioners argue that it 

presents reasons for EPA to reconsider the Findings in 

general. 

Petitioners argue that the Proposed Tailoring Rule is 

of central relevance to the Findings because it involves 

the PSD and title V permitting requirements that flow as an 

inevitable result of the Findings, and the impacts of such 

permitting are relevant to the Findings. e.g., SLF 5th

Supp. at 15; Ohio Coal Assn. at 4. They point to the fact 

that the Tailoring Rule was proposed, and comments thereon 

were received, after the close of the comment period for 

the Findings, and request that EPA grant reconsideration 

and re-open the Findings docket “to allow the public to 

comment on the implications of the Tailoring Rule[sic] to 

the form and content of the Endangerment Finding,” SLF 5th

 

46 The Final Prevention of Significant Deterioration (PSD) and Title V 

Greenhouse Gas Tailoring Rule was signed on May 13, 2010, and published 

June 3, 2010. 75 FR 31514 (June 3, 2010). 
Page 161 of 217

Supp. at 15, and to “further explore the extent to which 

implementation of the Endangerment Finding is practically 

impossible...since impossibility calls into question all 

justification for the Endangerment Finding.” Ohio Coal 

Assn. at 4. 

At least one petitioner points to the alleged 

implementation problems identified in the Proposed 

Tailoring Rule and comments received thereon as a basis for 

reconsidering the appropriateness of the Findings. Ohio 

Coal Assn. at 6-9. The petitioner argues that despite 

statements in the final Findings that EPA did not consider, 

and indeed could not have considered, policy concerns about 

the repercussions of impact of the finding when making the 

endangerment finding, EPA did “give credence and 

expression” and “did in fact consider the widespread and 

economically crippling” PSD permitting implementation 

issues. Ohio Coal Supp. at 15, 18. Therefore, the 

petitioner continues, new information about EPA’s ability 

to tailor the PSD program justifies granting 

reconsideration. Specifically, the petitioner cites to 

comments filed by state permitting authorities that they 

allege call into question the approach EPA proposed in the 

Tailoring Rule to address the negative impacts that EPA 

acknowledges “would inexorably flow from the Endangerment 
Page 162 of 217

Finding – that is, triggering the PSD and Title V 

permitting requirements at the low applicability levels 

provided under the Clean Air Act.” Ohio Coal Supp. at 16-

18. They claim that statements made by state permitting 

agencies about the ability of the proposal to address state 

law concerns, and the remaining burden even at the higher 

thresholds all undermine EPA’s claim that it can fashion a 

reasonable and common-sense solution to the perceived 

problem. Thus, petitioners conclude, the “most viable and 

sensible option” would be instead for EPA to withdraw the 

Findings until the impacts of the PSD and title V 

permitting programs can be fully assessed and resolved. 

Ohio Coal Assn. at 8; Ohio Coal Supp. at 22. 

Another petitioner provides slightly different reasons 

for claiming the Proposed Tailoring Rule necessitates 

granting reconsideration and re-opening the Findings for 

comment.47 This petitioner argues that the Proposed 

Tailoring Rule reflects an acknowledgement by EPA that 

regulating GHG under the CAA is absurd. Chamber at 3. The 

petitioner also argues that new information demonstrates 

 

47 This petitioner also stated in its petition that if EPA had neither 

“granted the petition nor contacted the [petitioner] to establish a 

mutually agreeable schedule for reconsideration by April 14, 2010, such 

inaction will be deemed a denial of the petition.” Chamber at 1. No 

EPA action, or inaction, other than this Decision and supporting 

material constitutes a denial of the petitions. See, e.g., Final LDVR, 

75 FR at 25402; EPA’s Combined Opposition to Remand (filed April 29, 

2010 in D.C. Cir. No. 09-1322). 
Page 163 of 217

that some of the public health and welfare effects from 

stationary source emission reductions that EPA expected 

when issuing the Findings will be legally unavailable. Id. 

at 9-10. The petitioner alleges that EPA recognized the 

“ill-fit” between pollutants like greenhouse gases, which 

become well-mixed in the atmosphere and cause global 

problems, and the existing structure of the CAA. The 

petitioner further claims that it was because of this illfit that EPA crafted the Tailoring Rule in order to avoid 

the absurd result of trying to regulate GHGs under part of 

the CAA. Petitioner’s suggested solution is for EPA to 

reconsider the Findings in light of EPA’s recognition that 

regulation of GHGs under the CAA is “absurd.” In so doing, 

the petitioner reiterates comments it, and others, 

submitted during the public comment period arguing that EPA 

retains discretion under Massachusetts to consider, among 

other things, the impacts of an endangerment finding when 

deciding whether to issue an endangerment findings. 

Chamber at 10-12. 

More specifically, the petitioners argue that the 

Supreme Court decision did not address the issue of whether 

GHGs could be regulated under the CAA consistent with 

Congress’ intent and without triggering absurd results. 

Chamber at 11. Rather, they contend, the Supreme Court 
Page 164 of 217

decision was about the narrow issue of whether GHGs were 

air pollutants under CAA section 202(a). Chamber at 11. 

Some petitioners argue that EPA should have informed the 

Supreme Court of the impact of a positive endangerment 

finding under CAA section 202(a) on stationary source 

permitting, and the fact that it may require EPA to resort 

to the absurdity doctrine; if EPA had, they continue, the 

Court may have issued a different opinion. CEI Supp. at 4-

5. Another petitioner argues that the Supreme Court left 

open the option of EPA declining to make an endangerment 

finding, and that in making its decision EPA must adhere to 

the customary mode of statutory interpretation in Chevron 

v. NRDC, 467 U.S. 837 (1984), considering all relevant 

statutory language, legislative history and absurd results 

that may apply when regulating GHGs under the CAA. Chamber 

at 12. 

Based on this alleged premise, the petition then turns 

to EPA’s statements in the Proposed Tailoring Rule 

concerning the potential absurd results that could result 

from applying the statutory permitting thresholds of 100 

and 250 tons per year (tpy) to GHGs, and the additional 

administrative impossibility that would result from 

applying these statutory thresholds immediately when GHGs 

are regulated under CAA section 202(a). Petitioner submits 
Page 165 of 217

additional evidence it alleges demonstrates the absurdity 

of regulating GHGs from stationary sources: (1) the PSD 

program is designed to address pollutants with localized 

impacts in specific geographic areas (e.g,. the NAAQS), 

and not global pollutants like GHGs; (2) the statutory 

thresholds would require burdensome, expensive, 

individualized emissions controls at hundreds of thousands 

of small emissions sources, contrary to Congressional 

intent; and (3) the application of permitting to GHGs would 

jeopardize economic growth, which would be particularly 

absurd in the current economic situation. Chamber at 15-17. 

Thus, according to this and other petitioners, EPA 

must reconsider the Findings in light of the absurd results 

that would result from GHGs being regulated pollutants 

under the PSD and title V permitting programs. See, e.g., 

Chamber at 18; CEI Supp. at 5. Specifically, petitioners 

argue that the absurdity doctrine demands that EPA consider 

whether regulating GHGs under the CAA as a whole is absurd 

or not, but that EPA completely ignored this possibility 

when developing the Findings. Rather than relying on the 

absurd results doctrine to merely “tailor” the PSD and 

title V permitting programs, petitioners argue that EPA 

should rely on it to avoid creating the permitting program 

dilemma in the first place, or at the very least take 
Page 166 of 217

comment on that option. Chamber at 18-19; CEI Supp. at 5. 

At least one petitioner contends that case law regarding 

the absurd results doctrine requires adopting the 

narrowest, most restrictive interpretation of the statute, 

and that there may be an interpretation that authorizes EPA 

to avoid making the endangerment finding in the first 

place, not one that merely addresses the PSD and title V 

statutory thresholds (e.g., by interpreting “emissions” or 

“major emitting facility” narrowly). Chamber at 18-19. 

Petitioners argue that given EPA’s failure to consider this 

alternative, coupled with the alleged acknowledgement that 

the CAA motor vehicle rules are not necessary to achieve 

public health and welfare advantages in light of the NHTSA 

CAFE rule (see below), EPA must reconsider the Findings. 

See, e.g., Chamber at 23. 

Finally, other petitioners argue that the Proposed 

Tailoring Rule itself is illegal, pointing to numerous 

industry comments filed on the proposal. They contend that 

since the Tailoring Rule is illegal, it is “a patently 

unconstitutional attempt by the Executive Branch to 

unilaterally amend a statute.” SLF 5th Supp. at 16. In 

summary, they conclude that since EPA cannot regulate GHGs 

under the CAA without ignoring part of the statute, it 

cannot regulate GHGs in a manner consistent with the CAA 
Page 167 of 217

and any attempt to do so is beyond EPA’s legal authority, 

arbitrary and capricious, and an abuse of discretion. Id. 

at 17-19. The petitioners also contend that EPA’s 

Endangerment Finding is arbitrary and capricious and an 

abuse of discretion because, they allege, it is 

climatically pointless as well. They state that rather 

than undertake a course of illegal action, especially one 

that they allege does not have any detectable effect, EPA 

should start over and reconsider the Findings. Id. 

EPA is denying the petitions for reconsideration that 

raise objections based on the Proposed Tailoring Rule 

because these objections are not of central relevance to 

the outcome of the final Findings and/or could have been 

raised during the public comment period. 

These objections are not of central relevance to the 

Findings for three primary reasons discussed in more detail 

below. First, as EPA noted in the Findings, the impact of 

regulations that may flow from a positive endangerment 

finding, even if absurd, is not a relevant consideration to 

the science based question of whether air pollution may 

reasonably be anticipated to endangerment public health or 

welfare. See, 74 FR at 66501, 66515-16; RTC volume 11 at 

4-5. Thus, EPA disagrees with a fundamental basis for 

petitioners’ objections based on the Proposed Tailoring 
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Rule – i.e., that EPA could or must decline to issue an 

endangerment finding under CAA section 202(a), regardless 

of the scientific evidence relevant to determining 

endangerment, based on concerns with implementing 

stationary source permitting. Second, even if the absurd 

results doctrine could influence EPA’s interpretation of 

CAA section 202(a) after the Supreme Court’s decision in 

Massachusetts, EPA’s approach to resolving the absurdity is 

reasonable because it focuses narrowly on that part of the 

CAA where the absurdity originates while giving effect to 

other statutory provisions, in order to balance the goal of 

improving public health and the environment with the goal 

of avoiding absurd results. Third, EPA disagrees with the 

petitioners who argue that because EPA is relying on the 

absurd results doctrine as a result of the Findings, the 

Findings themselves must therefore be illegal. Reliance on 

a doctrine of administrative law when interpreting a 

statute is not an indication of the illegality of agency 

action; indeed, it shows just the opposite. By applying, 

inter alia, the doctrines of absurd results and 

administrative necessity, EPA has been able to issue 

effective regulations addressing greenhouse gases while 

avoiding the absurd results that could arise from 

immediately applying the statutory thresholds for PSD and 
Page 169 of 217

title V to greenhouse gases. Thus, petitioners’ objections 

do not provide substantial support for the argument that 

the final Findings should be revised. 

More specifically, EPA stated the following in the 

Findings in response to comments urging EPA to delay making 

an endangerment finding based on, among other things, 

concerns about the impact of the PSD program: 

“EPA agrees with the commenters who argue that 

the Supreme Court decision held that EPA is limited to 

consideration of science when undertaking an 

endangerment finding, and that EPA cannot delay 

issuing a finding due to policy concerns if the 

science is sufficiently certain (as it is here). The 

Supreme Court stated that “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” 549 U.S. at 533. Some 

commenters point to this last provision, arguing that 

the policy reasons they provide are a “reasonable 

explanation” for not moving forward at this time. 

However, this ignores other language in the decision 

that clearly indicates that the Court interprets the 
Page 170 of 217

statute to allow for the consideration only of 

science. For example, in rejecting the policy 

concerns expressed by EPA in its 2003 denial of the 

rulemaking petition, the Court noted that “it is 

evident [the policy considerations] have nothing to do 

with whether greenhouse gas emissions contribute to 

climate change. Still less do they amount to a 

reasoned justification for declining to form a 

scientific judgment. Id. at 533-34 (emphasis added).

Moreover, the Court also held that “[t]he 

statutory question is whether sufficient information 

exists to make an endangerment finding” Id. at 534. 

Taken as a whole, the Supreme Court’s decision clearly 

indicates that policy reasons do not justify the 

Administrator avoiding taking further action on the 

question here” (74 FR 66501,December 15, 2009). 

Furthermore, EPA noted the following when responding 

to comments arguing that EPA should consider the impact of 

regulating GHGs when determining whether they endanger 

public health and welfare: 

“At their core, these comments are not about 

whether commenters believe greenhouse gases may 

reasonably be anticipated to endanger public health or 

welfare, but rather about commenters’ dissatisfaction 
Page 171 of 217

with the decisions that Congress made regarding the 

response to any endangerment finding that EPA makes 

under CAA section 202(a). * * * 

What these comments object to is that Congress 

has already made some decisions about next steps after 

a finding of endangerment, and the commenters are 

displeased with the results. But if this is the case, 

commenters should take up their concerns with 

Congress, not EPA. EPA’s charge is to issue new motor 

vehicle standards under CAA section 202(a) applicable 

to emissions of air pollutants that cause or 

contribute to air pollution which may reasonably be 

anticipated to endanger public health or welfare. It 

is not to find that there is no endangerment in order 

to avoid issuing those standards, and dealing with any 

additional regulatory impact. 

Indeed, commenters’ argument would insert policy 

considerations into the endangerment decision, an 

approach already rejected by the Supreme Court. 

First, as discussed in Section I.B of these Findings, 

in Massachusetts v. EPA, the court clearly indicated 

that the Administrator’s decision must be a 

“scientific judgment.” 549 U.S. at 534. She must 

base her decision about endangerment on the science, 
Page 172 of 217

and not on policy considerations about the 

repercussions or impact of such a finding” 

74 FR at 66515; December 15, 2009). 

Thus, petitioners are wrong in their claim that either 

EPA statements in the Proposed Tailoring Rule, or comments 

received thereon, regarding potential implementation 

difficulties in the PSD or title V permitting programs are 

legally relevant at all, let alone of central relevance, to 

EPA’s Endangerment Findings.48 The agency’s statements in 

the Findings that it “does not believe that the impact of 

regulation under the CAA as a whole . . . .will lead to the 

panoply of adverse consequences that commenters predict,” 

and that “EPA has and will continue to take a measured 

approach to address greenhouse has emissions” do not mean 

that EPA gave “credence and expression to one key negative 

impact” as one petitioner alleges. Ohio Coal Supp. at 15. 

These statements, which immediately follow EPA’s 

explanation of how the Administrator must look at the 

science and not policy consideration, are merely EPA’s 

 

48 We note that EPA has addressed the concerns about the approach set 

forth in the Proposed Tailoring Rule raised by state permitting 

authorities. In response to the very comments raised by petitioners 

here, as well as other comments, EPA revised its approach for 

implementing its tailoring rule approach to allow for faster state 

adoption of the solution. Final Prevention of Significant 

Deterioration (PSD) and Title V Greenhouse Gas Tailoring Rule 75 FR at 

31518, 31579-84 (June 3, 2010) (Final Tailoring Rule). Moreover, EPA 

also finalized applicability thresholds that are higher than those 

proposed, and otherwise refined the phase-in of permitting for GHGs to 

better accommodate the workload. Id. at 31523-25. 
Page 173 of 217

response to the dire predictions submitted by commenters. 

EPA did not and could not consider such impacts in making 

its science based judgment on endangerment. 

EPA further disagrees with the arguments that it must 

grant reconsideration and reopen the Findings because since 

the close of the comment period EPA has recognized that the 

Findings would lead to the LDVR, which triggers the PSD and 

title V requirements, which in turn would give rise to 

“absurd results” in the permitting provisions applicable to 

some stationary sources. The fact that the impacts from 

PSD and title V permitting may be absurd does not mean that 

EPA can reinterpret section 202(a) to allow the 

consideration of those absurd results, and then find no 

endangerment or avoid making a determination on 

endangerment. 

What petitioners fail to analyze is how, given the 

overwhelming science supporting the endangerment finding 

(see above), EPA could decline to issue the Findings 

because of policy/implementation concerns unrelated to the 

science and unrelated to the question of whether there is 

endangerment, and not violate the Supreme Court’s decision 

in Massachusetts v. EPA. As discussed above, EPA disagrees 

with petitioners who argue that “Massachusetts requires EPA 

to carefully consider [the absurdity doctrine] implications 
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for the Agency’s overall statutory interpretation.” Chamber 

at 13. The Supreme Court was clear that GHG fit within the 

definition of “air pollutant” under the CAA, and that when 

considering the question of endangerment the Administrator 

may consider only the science. EPA “must ground its 

reasons for action or inaction in the statute,” and the 

statutory endangerment provision in section 202(a) required 

that EPA’s “exercise of judgment must relate to whether an 

air pollutant ‘cause[s ], or contribute[s] to, 

endangerment.” This was a “direction to exercise 

discretion within defined statutory limits,” and the Court 

explicitly rejected EPA’s authority to exercise its 

judgment for policy reasons not related to “compl[iance] 

with this clear statutory command.” Massachusetts at 532-

533. Petitioners would have us ignore the clear mandate 

of the Court’s decision on the premise that if the case had 

been argued differently, the Court would have rendered a 

different opinion. EPA reasonably followed the 

instructions from the Supreme Court as provided in 

Massachusetts. 

Even if EPA had the authority and could reconsider its 

statutory authority under CAA section 202(a) in light of 

the absurdity doctrine, rather than follow petitioners’ 

implied approach, EPA would follow the approach set out in 
Page 175 of 217

the Final Tailoring Rule – a narrow solution that focuses 

on that part of the CAA where the absurdity originates. 

EPA’s approach balances the goal of improving public health 

and the environment by tackling air pollution problems with 

the goal of avoiding absurd results.49 Petitioners would 

apply the absurd results doctrine too broadly, undertaking 

a sweeping approach that negates any and all regulation of 

GHGs under the CAA in order to avoid problems that have 

arisen in specific programs. EPA’s targeted use of the 

absurd results doctrine in the Tailoring Rule is the better 

approach to reconciling all its obligations under the CAA. 

EPA has interpreted the statute as a whole, and interpreted 

it in a manner that does not allow difficulties in one 

program to nullify the various other Congressional 

 

49 In response to objections which are based in part on 

allegations that EPA must reconsider its final decision 

because new evidence allegedly shows that the LDVR will not 

get meaningful reductions, EPA has already stated in the 

final Findings that it does not need to find that any 

attendant regulations flowing from an endangerment finding 

would “fruitfully attack” or prevent at least a substantial 

part of the danger in order to find endangerment. 74 FR at 

66507-08. 

Moreover, contrary to one petitioner’s implied allegation, 

EPA did not consider the benefits resulting from stationary 

source emissions reductions when issuing the Findings, and 

the petitioner did not point to any evidence that EPA did 

base the Findings on such considerations. Finally, to the 

extent petitioners are arguing that EPA should reevaluate 

its approach to absurd results because there is little 

environment or public health benefit from the LDVR which 

followed the Findings, EPA disagrees. See Section IV.B 

responding to comments regarding NHTSA rules. 
Page 176 of 217

provisions that may be relevant to climate change under the 

CAA. 

Applying the Chevron two step test, EPA must, at Step 

1, determine Congressional intent. Chevron U.S.A. v. NRDC, 

467 U.S. 837 (1984). Under the absurd results doctrine 

“the literal meaning of statutory requirements should not 

be considered to indicate Congressional intent if that 

literal meaning would produce a result that is senseless or 

that is otherwise inconsistent with – and especially one 

that undermines – underlying congressional purpose.” Final 

Tailoring Rule, 75 FR at 31517. Looking at section 202(a) 

of the CAA, congressional intent appears clear, under 

Chevron Step 1, that Congress intended the Administrator to 

regulate emissions of air pollutants from new motor 

vehicles if the Administrator found that such emissions 

cause or contribute to air pollution which endangered 

public health or welfare. The Supreme Court stated that 

“[i]f EPA makes a finding of endangerment, the Clean Air 

Act requires the agency to regulate emissions of the 

deleterious pollutant from new motor vehicles.” 

Massachusetts at 533. Moreover, the Supreme Court has held 

that when making the endangerment finding the Administrator 

must look only at the science. There are no absurd results 

in the specific actions under section 202(a) of either 
Page 177 of 217

issuing an endangerment finding itself or in issuing 

standards applicable to GHG emissions from new motor 

vehicles. The absurd results stem from the contents of 

other statutory provisions, the PSD and Title V provisions 

discussed in the Tailoring Rule, not section 202(a). Even 

for those provisions, in the Final Tailoring Rule EPA 

specifically determined that the PSD and title V provisions 

indicate a clear congressional intent to cover at least the 

largest sources of GHGs under these programs. Id. at 

31517. Taking all of these facts together, EPA’s approach 

to utilization of the absurdity doctrine gives the greatest 

effect to the various provisions of the CAA and the overall 

congressional intent under the CAA, by minimizing the scope 

of limitation on statutory provisions in the application 

of the absurd results doctrine. 

As EPA discussed in the Tailoring Rule: 

“[i]n determining and implementing congressional 

intent, it is important that the statutory provisions 

at issue be considered together – (1) The obligation 

to make a determination on endangerment and 

contribution under CAA section 202(a); (2) if 

affirmative endangerment/cause or contribute findings 

are made, the obligation to promulgate standards 

applicable to the emissions of any such air pollutant 
Page 178 of 217

from new motor vehicles or new motor vehicle engines 

under CAA section 202(a); and (3) the PSD and title V 

applicability provisions. The most appropriate 

reading, and certainly a reasonable reading, is that 

we are required to take the action we have taken, that 

is to issue the findings, promulgate the LDVR, and 

promulgate the Tailoring Rule. Our approach gives 

effect to as much of Congress’s intent for each of 

these provisions, and the CAA as whole, as possible. 

With respect to the endangerment/cause or 

contribute findings under CAA section 202(a), 

congressional intent is clear that, as we stated in 

making the Findings and the Supreme Court held in 

Massachusetts v. EPA, we are precluded from 

considering factors other than the science based 

factors relevant to determining the health and welfare 

effects of the air pollution in question. 

Accordingly, as discussed above, EPA determined that 

the Agency was precluded from deferring or foregoing 

the findings due to concern over impacts on stationary 

sources affected by PSD or title V requirements. See

74 FR at 66496, 66500-01 (“Taken as a whole, the 

Supreme Court’s decision clearly indicates that policy 

reasons do not justify the Administrator avoiding 
Page 179 of 217

taking further action on the questions here.”); see 

also Massachusetts v. EPA, 549 U.S. at 533; see also 

(74 FR 66515-16, December 9, 2009) (The Administrator 

“must base her decision about endangerment on the 

science, and not on the policy considerations about 

the repercussions or impact of such a finding.”). 

Moreover, as EPA also noted, “EPA has the ability to 

fashion a reasonable and common-sense approach to 

address greenhouse gas emissions and climate change. 

74 FR at 66516.” (75 FR 31574, June 3, 2010)(footnote 

omitted) 50. 

The petitioners merely continue to disagree with EPA’s 

interpretation of the Supreme Court decision and question 

EPA’s ability to address permitting concerns, rather than 

provide anything new in their petitions on this topic. 

To the extent the petitioners are requesting that EPA 

reconsider and defer or forego issuance of the Findings to 

avoid causing an absurd result from implementation of the 

separate PSD and title V programs until such time as EPA 

could fully implement these programs without an absurd 

result, underlying this claim is the assumption that this 

 

50 This reasonable and common-sense approach includes the kind of step 

by step approach that includes regulation of GHG emissions from new 

motor vehicles, as described by Justice Stevens in Massachusetts, when 

discussing the issue of standing. Id. at 524. 
Page 180 of 217

approach would allow EPA to avoid the “absurd results” that 

are discussed in the Tailoring Rule, which states: 

“...there is no basis at this point to determine 

that streamlining will ultimately allow full 

compliance with the PSD and title V requirements. 

Rather, it is possible that EPA may conclude that none 

of the available streamlining techniques will allow 

all GHG sources at the statutory thresholds to comply 

with PSD and title V requirements in a manner that 

does not impose undue costs on the sources or undue 

administrative burdens on the permitting authorities. 

Under these circumstances, EPA may then permanently 

exclude GHG source categories from PSD or title V 

applicability under the absurd results doctrine. 

Moreover, it may well take many years before EPA is in 

a position to come to a conclusion about the extent to 

which streamlining will be effective and therefore be 

able to come to a conclusion as to whether any source 

categories should be permanently excluded from PSD or 

title V applicability. In our rulemaking today, we 

describe what actions we expect to take in the first 6 

years after PSD and title V are triggered for GHG 

sources, and we may well be in a situation in which we 

continue to evaluate streamlining measures and PSD and 
Page 181 of 217

title V applicability to GHG sources after this 6-year 

period. 

Accordingly, deferring the endangerment/cause or 

contribute findings and LDVR until such time that PSD 

and title V streamlining would allow full 

implementation of these programs at the statutory 

limits would serve only to delay the benefits of the 

LDVR, as well as the benefits that come from phasing 

in implementation of the PSD program to cover larger 

sources first. It would rely on an assumption that is 

unfounded at this point, that is, that such full 

compliance will be required at some point in the 

future. Delaying the emissions benefits of the LDVR 

and the related emissions benefits from partial 

implementation of the PSD program fails to implement 

Congress’ intent that the endangerment/cause or 

contribute findings “shall” lead to emissions 

standards for new motor vehicles contributing to the 

endangerment, and related emissions controls for the 

same air pollutant under the PSD program. EPA need 

not determine at this time what approach would be 

appropriate if there was a determination that full 

compliance with PSD and title V would in fact occur at 

some point in the future. In this case, absent such a 
Page 182 of 217

determination, it would be improper to rely on 

speculation of such a future possibility as a basis 

under section 202(a) to defer or forego issuance of 

the LDVR on the grounds that EPA should defer or 

forego the LDVR to avoid causing an absurd result. 

Likewise there is no basis to defer proceeding at this 

time with the streamlining of the PSD and title V 

programs. 

With respect to the PSD and title V applicability 

requirements, as we discuss elsewhere, we believe that 

Congress expressed a clear intent to apply PSD and 

title V to GHG sources and that the phase-in approach 

incorporated in the Tailoring Rule is fully 

appropriate. Proceeding now with the 

endangerment/contribution findings and LDVR, even if 

phasing-in of the PSD and title V programs is 

required, is consistent with our interpretation of the 

PSD and title V applicability requirements. Delaying 

the endangerment/contribution findings or LDVR, and 

thereby delaying the triggering of PSD and title V 

requirements for GHG sources, would lead to the loss 

of a practicable opportunity to implement the PSD and 

title V requirements in important part, and thereby 

lead to the loss of important benefits. As discussed 
Page 183 of 217

elsewhere, promulgating the LDVR and applying the PSD 

and title V requirements to the largest GHG sources, 

as we do in this Tailoring Rule, is practicable 

because the sources that would be affected by the 

initial implementation steps we promulgate in this 

rule are able to bear the costs and the permitting 

authorities are able to bear the associated 

administrative burdens. Promulgating the LDVR now 

provides important advantages because the sources that 

would be affected by the initial steps are responsible 

for most of the GHG emissions from stationary sources. 

It should also be noted that as discussed 

elsewhere in this rulemaking, our ability to develop 

appropriate streamlining techniques for PSD and title 

V requirements is best done within the context of 

actual implementation of the permitting programs, and 

not in isolation of them. That is, because the great 

majority of GHG sources have not been subject to PSD 

and title V requirements, we will need to rely on the 

early experience in implementing the permitting 

requirements for the very large sources that initially 

will be subject to those requirements in order to 

develop streamlining techniques for smaller sources. 

It is the real world experience gained from this 
Page 184 of 217

initial phase that will allow EPA to develop any 

further modifications that might be necessary. This 

would not and could not occur if the LDVR were delayed 

indefinitely or permanently, so that PSD and title V 

requirements were not triggered. It is unrealistic to 

expect that delaying action until a future tailoring 

rule could resolve all of the problems identified in 

this rulemaking, absent any real world implementation 

experience. 

At its core, commenters’ argument is that EPA 

should delay (if not forego altogether) doing anything

to address GHG emissions and the problems they cause 

until it can do so in a way that does not cause any 

implementation challenges, even if that delay results 

in continued endangerment to public health and 

welfare. EPA does not take such a myopic view of its 

duties and responsibilities under the CAA. Congress 

wrote the CAA to, among other things, promote the 

public health and welfare and the productive capacity 

of the population. CAA §101(b)(1). EPA’s path 

forward does just this. Thus, proceeding with the 

endangerment/cause or contribute findings, the LDVR, 

and with PSD and title V through the phase-in approach 

of the Tailoring Rule maximizes the ability of EPA to 
Page 185 of 217

achieve the Congressional goals underlying CAA 

sections 202(a) and the PSD and title V provisions, 

and the overarching CAA goal of protecting public 

health and welfare. Congress called for EPA (1) to 

determine whether emissions from new motor vehicles 

contribute to air pollution that endangers, (2) if 

that the determination is affirmative, to issue 

emissions standards for new motor vehicles to address 

the endangerment, and (3) to implement the PSD and 

Title V program to address similar emissions in their 

permitting program as another tool to address the air 

pollutant at issue. Delaying both the LDVR and 

PSD/title V implementation, as commenters have called 

for, would run directly counter to these Congressional 

expectations. Commenters’ calls for deferral or 

foregoing of the findings or LDVR are generally 

phrased in a conclusory fashion, and do not 

demonstrate how EPA could take the required CAA 

actions concerning GHGs while remaining within the 

requirements of each of the various CAA provisions, 

and achieving the overall goals of the CAA. As such 

the comments do not provide a valid basis for the 

deferral of agency action they suggest.” (75 FR 31575-

56; June 3, 2010). 
Page 186 of 217

As explained above, EPA is resolving the absurdity 

caused by the statutory thresholds in the PSD and title V 

permitting programs not by avoiding an endangerment finding 

or avoiding all regulation under the CAA, but rather by 

interpreting the statute in a way that gives effect to the 

greatest extent possible to both section 202(a) and the 

applicable permitting provisions. This gives the greatest 

effect possible to the congressional intent about 

addressing air pollutant problems that endanger public 

health and welfare, while also focusing the permitting 

programs, at least initially, on large stationary sources. 

EPA’s targeted use of the absurd results doctrine in the 

Tailoring Rule is a reasonable approach to reconcile the 

various statutory obligations under the CAA at issue here. 

EPA also disagrees with petitioners who argue either 

implicitly or explicitly that EPA has admitted, through its 

invocation of the absurd results doctrine in the Proposed 

Tailoring Rule, that it cannot regulate GHGs under the CAA 

without violating the statute. While, in the Tailoring 

Rule, EPA has noted that applying the statutory thresholds 

in the PSD and title V programs to greenhouse gases 

immediately for all sources would present problems, and may 

indeed lead to absurd results even in the long run, EPA did 

not and does not take the position that all regulation of 
Page 187 of 217

GHGs under the CAA leads to absurd results or is illegal. 

In fact, just the opposite is true. EPA has issued 

reasonable, effective GHG emissions standards for light 

duty vehicles, and has announced plans for further GHG 

emissions standards for later model year light-duty 

vehicles. EPA also plans to propose the same for heavyduty motor vehicles. Moreover, by applying, inter alia, 

the doctrines of absurd results and administrative 

necessity, EPA has been able to avoid the absurd results 

that could arise from applying the statutory thresholds for 

PSD and title V to greenhouse gases.51 The concept behind 

the absurd results doctrine is that an agency can (if not 

must) ignore the literal meaning of a statute in order to 

effectuate congressional intent. That is exactly what 

EPA’s approach does – ignore only the statutory thresholds 

for PSD and title V in order to effectuate congressional 

intent under the CAA as a whole. EPA’s reliance on one or 

 

51 Contrary to one petitioner’s argument, EPA did not craft 

the Tailoring Rule in response to the global nature of 

greenhouse gas concentrations and climate change. Rather, 

it is the much higher amounts at which greenhouse gases are 

emitted by stationary sources, compared to existing 

criteria and other regulated air pollutants, that 

necessitated EPA’s reasonable approach to permitting. The 

absurdity that EPA was trying to avoid was permitting 

stationary sources much smaller than Congress intended when 

writing the permitting provisions of the CAA. The global 

nature of greenhouse gases and climate change was not the 

reason for the Tailoring Rule. 
Page 188 of 217

more doctrines of administrative law when interpreting the 

statute is not evidence of the illegality of EPA’s actions; 

rather it is evidence of the reasonable approach EPA took 

to interpreting and implementing the statute. 

Finally, EPA is also denying the petitions because, 

while the Tailoring Rule was proposed after the close of 

the comment period for the Findings, EPA discussed the 

impact of applying the PSD and title V statutory thresholds 

to GHGs, and the potential need to tailor those programs as 

appropriate, in the July 2008 ANPR. 73 FR 44354, 44497-

514, 44503 (“we have identified two legal doctrines that 

may provide EPA with discretion to tailor the PSD program 

to GHGs: Absurd results and administrative necessity.”), 

44512 (discussing same legal theories in context of title 

V). Indeed, EPA received comments from some of the same 

entities that are petitioning for reconsideration now 

regarding the Agency’s position about its ability to craft 

a reasonable approach to addressing GHGs under the CAA, 

including the CAA permitting programs. See, e.g., Comments 

submitted by Marlo Lewis for the Competitive Enterprise 

Institute (EPA-HQ-OAR-2009-0171-2898.1). Thus, while EPA 

itself may have elaborated regarding the potential for 

absurd results from GHG permitting at the statutory 

thresholds in the Proposed Tailoring Rule, the issue was 
Page 189 of 217

not raised for the first time in the Tailoring Rule; it had 

already been raised in the ANPR, and there was nothing 

preventing petitioners from commenting on the issue in 

their comments on the proposed Findings (as indeed some 

did). Commenters on the proposed Findings also argued that 

the Supreme Court was unaware of the impacts of the 

permitting programs when deciding Massachusetts. RTC 

Volume 11 at 5. Thus, objections based on the need to 

apply the absurd results doctrine to the PSD and title V 

programs, and on arguments related to how EPA defended its 

actions in Massachusetts, could have been (and indeed were) 

raised during the comment period on the Findings and are 

not appropriately raised in petitions for reconsideration. 

B. NHTSA Rule

The Chamber of Commerce raised objections based on the 

authority of the National Highway Traffic Safety 

Administration (NHTSA) to issue Corporate Average Fuel 

Economy (CAFE) standards for new motor vehicles. 

Specifically, the Chamber argued that the federal 

government must choose between two alternative regulatory 

approaches: seeking to regulate GHG emissions using NHTSA’s 

authority, under EPCA as revised by EISA or, alternatively, 

regulating such emissions on authority of Title II of the 

CAA. According to the Chamber, NHTSA has recently 
Page 190 of 217

acknowledged it has adequate legal authority under EPCA and 

EISA to regulate greenhouse gas emissions, independent from 

EPA’s authority under CAA section 202(a), therefore EPA 

must reconsider the Endangerment Finding because it cannot 

claim to generate the public health benefits from CAA 

mobile source GHG emissions reductions. The Chamber argues 

that according to EPA, the Endangerment Finding, standing 

alone, produces no current public health or welfare 

benefits but will instead produce such benefits in the 

future, but only if it effectively serves as a precondition 

for the regulation of GHG emissions from new motor vehicles 

or some other category of emission sources. Thus, the 

Chamber concludes, EPA has justified the Endangerment 

Finding as a means to the end of new motor vehicle 

regulation. 

The Chamber claims that this core rationale for EPA’s 

Endangerment Finding and regulatory program can no longer 

bear scrutiny. It argues that if EPA affirmatively wishes 

to pursue an Endangerment Finding to regulate emissions 

from new motor vehicles, it must explain what it can add to 

a NHTSA-only rulemaking. According to the Chamber, EPA may 

not rely on a presumed need for motor vehicle regulations 

that could be accomplished through NHTSA regulations alone. 

(Chamber, 19-23) 
Page 191 of 217

Petitioner claims that EPA issued and justified the 

Endangerment Finding based on the need for emissions 

reductions from EPA regulation of new motor vehicles, and 

the expectation that such EPA regulation would achieve 

the expected emissions reductions. That argument 

mischaracterizes EPA’s position. 

Consistent with the statutory language, legislative 

history and Supreme Court case law, EPA determined whether 

atmospheric concentrations of greenhouse gases are 

reasonably anticipated to endanger public health or 

welfare, and based that determination on the scientific and 

other evidence relevant to the issues of endangerment. As 

EPA made clear, CAA section 202(a) limited the issues EPA 

could consider in making a determination concerning 

endangerment, and they did not include consideration of the 

degree of reductions that would reasonably be achieved by 

regulations to control emissions from new motor vehicles. 

EPA clearly stated that: 

“As the Supreme Court made clear in Massachusetts 

v. EPA, EPA’s judgment in making the endangerment and 

contribution findings is constrained by the statute, 

and EPA is to decide these issues based solely on the 

scientific and other evidence relevant to that 

decision. EPA may not "rest[] on reasoning divorced 
Page 192 of 217

from the statutory text," and instead EPA’s exercise 

of judgment must relate to whether an air pollutant 

causes or contributes to air pollution that endangers. 

Massachusetts v. EPA, 549 U.S. at 532. As the Supreme 

Court noted, EPA must "exercise discretion within 

defined statutory limits." Id. at 533. EPA’s belief 

one way or the other regarding whether regulation of 

greenhouse gases from new motor vehicles would be 

"effective" is irrelevant in making the endangerment 

and contribution decisions before EPA. Id. Instead 

"[t]he statutory question is whether sufficient 

information exists to make an endangerment finding" 

Id. at 534. 

The effectiveness of a potential future control 

strategy is not relevant to deciding whether air 

pollution levels in the atmosphere endanger. It is 

also not relevant to deciding whether emissions of 

greenhouse gases from new motor vehicles contribute to 

such air pollution. Commenters argue that Congress 

implicitly imposed a third requirement, that the 

future control strategy have a certain degree of 

effectiveness in reducing the endangerment before EPA 

could make the affirmative findings that would 

authorize such regulation. There is no statutory text 
Page 193 of 217

that supports such an interpretation, and the Supreme 

Court makes it clear that EPA has no discretion to 

read this kind of additional factor into CAA section 

202(a)’s endangerment and contribution criteria. In 

fact, the Supreme Court rejected similar arguments 

that EPA had the discretion to consider various other 

factors besides endangerment and contribution in 

deciding whether to deny a petition. Massachusetts v. 

EPA, 549 U.S. at 532–35.” (74 FR 66496, 66507-8; 

December 15, 2009). 

This excerpt was in response to comments arguing that 

EPA should take into account the emissions impacts of EPA’s 

then upcoming rule to control emissions of greenhouse gases 

from light-duty vehicles and trucks, and consider that the 

CAFE standards issued by NHTSA would effectively achieve 

the same reductions. Id at 66501, 66507. Just as the 

effectiveness of future motor vehicle regulations was not 

relevant to determining endangerment, EPA made it clear 

that CAA section 202(a) did not allow EPA to consider 

issues such as future adaptation and mitigation, which 

reflected how society responded to the issue of 

endangerment, not whether endangerment existed. Id. at 

66512-514. 
Page 194 of 217

Thus, it is clear that EPA did not justify or base its 

Endangerment Finding on either the need for emissions 

reductions from EPA regulations of new motor vehicles, or 

the expectation that such an EPA regulation would achieve 

emissions reductions. EPA rejected suggestions during the 

rulemaking that EPA refrain from issuing and Endangerment 

Finding because NHTSA has the authority to issue CAFE 

standards that also reduce greenhouse gases, as discussed 

above. The Chamber is raising basically the same issue 

raised in the rulemaking, and has presented no reason that 

would support any different response. EPA is rejecting 

Chamber’s request for the same reasons it rejected these 

same kinds of requests in the rulemaking. 

It is also clear that it was eminently practicable for 

the Chamber to raise this issue in the comment period. As 

described above, various commenters pointed to NHTSA’s 

separate authority, and argued that NHTSA would effectively 

achieve the same reductions as EPA, undermining the basis 

for EPA’s Endangerment Finding. Id. at 66507. Also see 

66544, in the context of the Contribution Finding. The 

Chamber raises the same kind of objection here, and could 

have raised it during the comment period. While they point 

to a subsequent statement by NHTSA indicating that NHTSA’s 

statutory authority is separate from EPA’s, that is not new 
Page 195 of 217

or different information concerning NHTSA’s authority and 

does not change the nature of the Chamber’s objection. 

Their failure to raise their objection in a timely manner 

is another reason to reject their request to reconsider on 

these grounds. 

As part of their argument, the Chamber claims that EPA 

must explain what it can add to a NHTSA-only rulemaking. 

This is one part of the argument raised above, and is 

rejected for the same reasons. As with the arguments 

discussed above, the Chamber could have raised this 

argument during the comment period, and the failure to do 

so is another reason to reject their request to reconsider 

on these grounds. 

In any case, EPA has explained in detail how the 

recently issued regulations under CAA section 202(a) to 

control emission of greenhouse gases from light-duty 

vehicles and trucks differ from NHTSA’s CAFE program for 

the same vehicles, and why it was important for EPA to 

issue its rule. In the final rule issuing greenhouse gas 

emissions standards for new motor vehicles, EPA responded 

to comments that it should delay issuance of the motor 

vehicle standards until a later time, to avoid concerns 

over stationary source permitting impacts. EPA stated: 
Page 196 of 217

“[The Supreme Court in Massachusetts] stated that 

under section 202(a), "[i]f EPA makes [the 

endangerment and cause or contribute findings], the 

Clean Air Act requires the agency to regulate 

emissions of the deleterious pollutant." 549 U.S. at 

534. As discussed above, EPA has made the two 

findings on contribution and endangerment. 74 FR 66496 

(December 15, 2009). Thus, EPA is required to issue 

standards applicable to emissions of this air 

pollutant from new motor vehicles. 

The Court properly noted that EPA retained 

“significant latitude” as to the “timing * * * and 

coordination of its regulations with those of other 

agencies” (id.). However it has now been nearly three 

years since the Court issued its opinion, and the time 

for delay has passed. In the absence of these final 

standards, there would be three separate Federal and 

State regimes independently regulating light-duty 

vehicles to increase fuel economy and reduce GHG 

emissions: NHTSA’s CAFE standards, EPA’s GHG 

standards, and the GHG standards applicable in 

California and other states adopting the California 

standards. This joint EPA–NHTSA program will allow 

automakers to meet all of these requirements with a 
Page 197 of 217

single national fleet because California has indicated 

that it will accept compliance with EPA’s GHG 

standards as compliance with California’s GHG 

standards. 74 FR at 49460. California has not 

indicated that it would accept NHTSA’s CAFE standards 

by themselves. Without EPA’s vehicle GHG standards, 

the states will not offer the Federal program as an 

alternative compliance option to automakers and the 

benefits of a harmonized national program will be 

lost. California and several other states have 

expressed strong concern that, without comparable 

Federal vehicle GHG standards, the states will not 

offer the Federal program as an alternative compliance 

option to automakers. Letter dated February 23, 2010 

from Commissioners of California, Maine, New Mexico, 

Oregon and Washington to Senators Harry Reid and Mitch 

McConnell (Docket EPA–HQ–OAR–2009–0472–11400). The 

automobile industry also strongly supports issuance of 

these rules to allow implementation of the national 

program and avoid "a myriad of problems for the auto 

industry in terms of product planning, vehicle 

distribution, adverse economic impacts and, most 

importantly, adverse consequences for their dealers 

and customers." Letter dated March 17, 2010 from 
Page 198 of 217

Alliance of Automobile Manufacturers to Senators Harry 

Reid and Mitch McConnell, and Representatives Nancy 

Pelosi and John Boehner (Docket EPA–HQ–OAR–2009–0472–

11368). Thus, without EPA’s GHG standards as part of a 

Federal harmonized program, important GHG reductions 

as well as benefits to the automakers and to consumers 

would be lost. In addition, delaying the rule would 

impose significant burdens and uncertainty on 

automakers, who are already well into planning for 

production of MY 2012 vehicles, relying on the ability 

to produce a single national fleet. Delaying the 

issuance of this final rule would very seriously 

disrupt the industry’s plans” (75 FR 25314, 25402; May 

7, 2010). 

EPA also noted that the greenhouse gas standards 

issued by EPA achieved greater overall reductions in 

greenhouse gases than NHTSA’s CAFE standards. Id at n.165, 

25402; also see 25397, 25549-50. Thus, EPA has explained 

in full the reasons for refusing to delay issuance of EPA’s 

motor vehicle emissions standards, and what EPA’s rule adds 

to NHTSA’s CAFE rule. As noted above, these issues are not 

relevant to the issues EPA considers in making a 

determination on endangerment under CAA section 202(a). 

C. Other Issues
Page 199 of 217

1. Effects of the Findings and Subsequent Rulemakings on 

States and Businesses 

Many of the petitioners provide detailed information 

regarding the impact that they allege would flow from the 

Findings; these discussions are in addition to arguments 

based on the Proposed Tailoring Rule (see Section IV.A of 

this Notice for the response to the arguments based on the 

Proposed Tailoring Rule). For example, the State of Texas, 

in addition to providing information regarding efforts the 

State has made to address GHGs, details harm it predicted 

could occur to the State through allegedly adverse impacts 

to its farming and ranching, mineral interest revenue 

stream, and oil and gas sector. Texas at 5-7, 32-34. The 

State also discusses what it describes as the “fallout” 

from the Findings. Id. at 34-38. More specifically, the 

State of Texas discusses resolutions and bills that have 

been introduced in the U.S. House of Representatives and 

the U.S. Senate, comments from the Small Business 

Administration’s Office of Advocacy on the Proposed 

Tailoring Rule,52 and various inquiries into, or statements 

about, the CRU e-mails and IPCC. 

 

52 The State of Texas stated that this letter was provided to the 

endangerment docket (EPA-HQ-OAR-2009-0171), but it was actually 

submitted to the docket for the Proposed Tailoring Rule (EPA-HQ-OAR2009-0571). 
Page 200 of 217

The State of Virginia, while not providing any 

additional information regarding the alleged impacts of the 

Findings, states that “EPA’s remote finding of endangerment 

to health and welfare fail to consider and properly weigh 

the offsetting harms to health and welfare necessarily 

flowing from economically destructive regulation.” 

Virginia at 3. 

The petitioners’ information regarding the impact to 

petitioners and others often follows sections of the 

petitions in which petitioners raise allegedly new concerns 

with the science underlying the Findings. The information 

regarding the impact from the Findings is most often 

provided in order to emphasize to EPA the necessity of 

reconsidering the Findings based on those earlier 

concerns.53 See, e.g., Texas at 35 (“In light of these ... 

concerns . . . the Administrator’s improper handling of the 

scientific assessment process takes on an even greater 

meaning.”); Letter from WV Coal Assn. at 1 (“EPA’s findings 

would have a grave impact on our industry and the thousands 

of West Virginian who depend on the production and use of 

our high quality coal everyday....This makes it all the more 

 

53 Petitioners also provide this information in the context of 

requesting an administrative stay of the Findings from EPA. See 

Section II for a discussion of EPA’s denial of these stay requests. 
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important that EPA suspend its decision and reconsider it 

in light of these important new developments.”). 

The objections based either explicitly or implicitly 

on EPA’s decision to not consider the impacts of greenhouse 

gas regulations when making the Findings could have been, 

and indeed were, raised during the public comment period on 

the Findings. Thus, they are not properly raised in CAA 

section 307(d) petition for reconsideration and are 

therefore denied. 

Moreover, as discussed elsewhere in this Decision and 

supporting material, this information is essentially 

irrelevant to the scientific based questions before EPA 

when making the endangerment and contribution findings. 

EPA already explained in the Findings how the potential 

impacts from the regulations that may follow an 

endangerment finding are not proper considerations when 

determining whether GHGs may reasonably be anticipated to 

endanger public health or welfare. See generally, 74 FR at 

66515-16; see also id. at 66515 (The Administrator “must 

base her decision about endangerment on the science, and 

not on policy considerations about the repercussions or 

impact of such a finding.”); id. at 66516 (“Therefore, it 

is reasonable to interpret the endangerment test as not 

requiring the consideration of the impacts of implementing 
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the statute in the even of an endangerment finding as part 

of the endangerment finding itself.”). 

Finally, as detailed elsewhere in this Decision and 

RTP document, the CRU e-mails and other scientific 

information provided by the petitioners do not call into 

question the underlying science, EPA’s reliance on it, or 

the Administrator’s final determination. 

2. A Formal Rulemaking Process is Not Required

One petitioner discusses why EPA should not only 

reconsider the Findings, but also utilize the formal 

rulemaking process in the reconsideration proceedings. 

Peabody Energy at IX-9 to IX-18. Essentially, the 

petitioner believes that the questions raised by the CRU emails and errors in IPCC AR4 are so serious that EPA’s 

responsibilities to address them can be discharged only 

through granting reconsideration, and undertaking a formal 

rulemaking process. More specifically, the petitioner 

states that “[a]n on-the-record proceeding is necessary to 

rectify the substantial flaws in the process that EPA has 

employed, flaws that stem from the abuses infecting the 

studies on which the Endangerment Finding is principally 

based.” Peabody Energy at IX-9. 

In support of its argument, petitioner first notes 

that while EPA may not be required by the CAA to undertake 
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an on-the-record proceeding, nothing prohibits EPA from 

undertaking more process than is required by statute. Id. 

at IX-9 to IX-10. The petitioner then argues that case law 

and “other authoritative guidance,” specifically guidance 

from the Administrative Conference of the United States 

(ACUS), “make clear than an evidentiary hearing” on the 

petitions for reconsideration is warranted. Id. at IX-10. 

The petitioner contends that a formal evidentiary hearing 

will fix EPA’s record, which they claim is “wholly 

inadequate” and cannot justify finding endangerment to 

public health.54 More specifically, they claim that a 

“responsive thrust and parry” about the science underlying 

the Administrator’s decision, including “secondary sources” 

such as the IPCC, should occur and that the informal 

rulemaking proceeding EPA undertook does not allow for 

this. Peabody Energy at IX-16. 

Comments suggesting that EPA undertake a formal 

rulemaking process, not only could have been raised, but 

were raised, during the comment period for the Findings. 

74 FR at 66504-05, 66510-12. Thus, they are not 

appropriately raised in petitions for reconsideration. 

Please see the above portions of the Findings, RTC Volume 

1, and Section III of this Decision for further discussion 

 

54 EPA responds to the argument regarding the public health finding in 

section IV.B.I of the Findings and Volume 5 of the RTC document. 
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on why EPA’s denial of the request for formal hearing in 

the Findings, and the agency’s continued reliance on the 

assessment reports, is reasonable. 

To the extent that the petitioners are re-raising 

these comments in light of the CRU e-mails and IPCC 

developments, and asking for EPA to reconsider its prior 

denial of the request for a formal rulemaking hearing, for 

the reasons explained elsewhere in this Decision and 

supporting materials, these materials do not necessitate 

EPA granting reconsideration, let alone initiating the 

exceedingly rare process of a formal, on-the-record 

rulemaking. When all is said and done, the CRU e=mails and 

IPCC errors do not call into question the science 

supporting the Administrator’s decision. They surely do 

not rise to the level of “extremely compelling 

circumstances” that petitioner argues would justify a court 

dictating that EPA undertake formal rulemaking procedures. 

Peabody Energy at IX-10. 

Petitioner argues that while EPA is not required by 

the CAA to follow a formal rulemaking process, EPA has the 

authority to convene such a hearing and nothing in the CAA 

should be read to “limit EPA’s discretion in deciding 

whether to do so.” Peabody Energy at IX-9. n. 494. The 

petition also notes that EPA is equipped to undertake such 
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a hearing, citing the existing procedures for 

adjudications, 40 C.F.R. § 22.3(a). While EPA may have the 

discretion to provide more process than the minimum 

required by CAA section 307(d), EPA notes that the petition 

does not discuss how a formal on-the-record hearing process 

would fit within the informal rulemaking proceedings 

mandated by the CAA. See 74 FR at 66505 (noting that 

original request also did not discuss how a formal hearing 

would fit with CAA requirements). Nor does it discuss how 

the 40 C.F.R. Part 22 regulations, which are entitled 

“Consolidated Rules of Practice Governing the 

Administrative Assessment of Civil Penalties and 

Revocation/Termination or Suspension of Permits” and cover 

administrative adjudicatory proceedings for specifically 

delineated civil penalty or permit actions, would authorize 

the type of hearing petitioner suggests, or even how they 

would work assuming EPA chose to apply them as suggested by 

petitioner. 

The cases cited by petitioner stand for the 

unsurprising proposition that some circumstances justify 

more or different procedures than others. But they do not, 

as petitioner alleges, lead to the inevitable conclusion 

that the only reasonable recourse for EPA is to undertake a 
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formal rulemaking process.55 Indeed, that would be a 

departure “from the very basic tenet of administrative law 

that agencies should be free to fashion their own rules of 

procedure.” Vermont Yankee Nuclear Power Corp. v. NRDC, 

435 U.S. 519, 544 (1978). In Vermont Yankee the Supreme 

Court rejected an argument similar to that being made by 

petitioner here – that the issues before the agency were so 

complex and important that they necessitated more process, 

including cross-examination, even if such procedures were 

beyond the minimum required. Id. at 539-49. Also see 

Kennecott, 684 F.2d at 1020 fn 33. 

To the extent that petitioner argues that EPA’s record 

is inadequate if it does not include the “thrust and parry” 

 

55 The extremely compelling circumstances found by courts in 

the cases cited by petitioners do not exist here. See 

People of the State of Illinois v. United States, 666 F.2d 

1066, 1082-83 (7th Cir. 1981) (court relied upon a 

combination of unique factors including that the Interstate 

Commerce Commission had allowed cross-examination on some 

information in an adjudicatory proceeding, but not other 

similar information, and the cross-examination had been 

found to be “critical to achieving an accurate 

determination of the facts.”); National Wildlife Federation 

v. Marsh, 721 F.2d 767, (11th Cir. 1983) (the court merely 

required the Army Corps of Engineers to follow its own 

longstanding internal procedures when issuing a permit). 

EPA also notes that two of the cases the petitioner cites 

for the proposition that “cross examination is the most 

effective way to ascertain the truth,” Peabody at IX-15, 

are criminal cases, therefore it is not surprising that 

cross-examination was at issue. The third, discussed 

above, involved a decision in which the agency had already 

decided to allow cross-examination. People, 666 at 1083.
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of a formal rulemaking hearing, with cross examination, EPA 

disagrees. Congress clearly indicated that the robust 

informal rulemaking procedures of CAA section 307(d) are 

appropriate for the myriad complex issues that EPA must 

address when issuing particular CAA rules. Nothing that 

petitioners have provided call into question EPA’s decision 

to follow the clear direction provided in section 307(d). 

Indeed, the robust informal rulemaking requirements of 

section 307(d) of the CAA ensure adequate and appropriate 

notice and comment for CAA decisions. See generally 74 FR 

66500-05 (discussing the public involvement in development 

of the Findings, including EPA’s careful review and 

response to more than 380,000 public comments). Moreover, 

the section 307(d) reconsideration process provides ample 

opportunity for petitioners, and any other interested 

party, to submit to EPA for consideration new information 

which they believe is of central relevance to the 

Administrator’s final decision, and hence necessitates 

reconsideration of that decision. Other than continuing to 

disagree with EPA’s denial of the original request for a 

formal rulemaking, and continuing to state its opinion that 

the science and regulatory impact from an endangerment 

finding demands more process, petitioner has not 

demonstrated why the clearly applicable procedures of 
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section 307(d) are inadequate, let alone why only the 

rarely-used formal rulemaking process is the only 

reasonable path forward. Petitioners have submitted over 

500 pages of reconsideration petitions, as well as 

attachments consisting of hundreds of pages that contain 

information including dozens of studies, more than 300 

pages of computer code, and more than 1000 e-mails. 

Peabody Energy and other petitioners have had a full 

opportunity, both in the underlying rulemaking and in the 

reconsideration process, to submit whatever information or 

evidence they want concerning the variety of scientific and 

other issues of concern to them, such as those identified 

at Peabody IX-12. EPA’s lengthy and detailed Denial, 

including this document and the RTP document, carefully 

examines each objection raised and explains why each 

objection is untimely and/or not of central relevance. The 

CAA reconsideration process provides ample opportunity for 

interested parties to present new information to EPA, and 

for EPA to examine that information. Petitioner has not 

identified what cross examination it thinks is required to 

“ensure that results reached by EPA reflect scientific 

truths”. For example, do they envision cross examination 

of all of the authors of the thousands of studies discussed 

in the rulemaking, or discussed in an assessment report? 
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Cross examination of every author and other participant in 

an assessment report? Cross examination of agency 

scientists? And for all of these, on what subjects and 

issues? The administrative record includes the assessment 

reports and their integration of the science within areas 

of climate research and across various areas of climate 

research, as well as EPA’s TSD and additional reports and 

studies provided by commenters. The proposed and final 

Findings also included the Administrator's judgments and 

conclusions on all of this evidence. Petitioners have 

failed to explain what facts they would like cross 

examination on, what witnesses they envision cross 

examining, and how any such examination would add in any 

way, much less a practical way, to the ability they already 

have, through submission of comments and petitions to 

reconsider, to attack and contest at length any and all of 

these parts of the informal rulemaking record. They have 

failed to demonstrate how their broad, general assertions 

of a better process would actually work as a practical way 

to better ensure the scientific integrity of the record 

before the Agency. It is quite reasonable for EPA to rely 

on the robust and in-depth informal rulemaking procedures 

followed in this rulemaking, as mandated by Congress, 
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rather than embark on the rarely-used formal rulemaking 

pathway. 

As discussed in the final Findings, the ACUS 

guidelines are non-binding recommendations regarding 

“important circumstances tending to suggest the 

desirability of such procedural devices”. 1 U.S.C. § 

305.76-3(1). EPA notes that the ACUS recommendations cited 

by petitioner are not specifically for the formal 

rulemaking proceedings suggested by petitioner. Rather, 

they are more general, for “[h]earing argument and other 

oral presentation, when the presiding agency official or 

officials may ask questions, including questions submitted 

by interested persons.” 1 U.S.C. § 305.76-3(1)(f). The 

CAA requires a hearing and opportunity for oral 

presentation, CAA § 307(d)(5), and EPA held two hearings 

during which interested parties could present their 

arguments and information and EPA could ask questions. 

Thus, EPA has already undertaken procedures similar to 

those recommended by the ACUS. 

Last, part of the recommendation of the ACUS not 

raised by petitioner is the following: 

An agency should employ any of the devices 

specified in paragraph 1 or permit crossexamination only to the extent that it believes 
Page 211 of 217

that the anticipated costs (including those 

related to increasing the time involved and the 

deployment of additional agency resources) are 

offset by anticipated gains in the quality of the 

rule and the extent to which the rulemaking 

procedure will be perceived as having been fair. 

1 U.S.C. § 305.76-3(3). For all the reasons stated above, 

in the final Findings, and elsewhere in this document and 

supporting material, EPA does not believe that the 

potential for gains in the quality of the Administrator’s 

decision, if any, would offset the costs, both in terms of 

agency resources and delay. Moreover, the section 307(d) 

rulemaking process is quite fair, providing adequate 

opportunity for everyone, and not just parties who could 

afford to participate in a formal hearing, to present their 

views. Contrary to petitioner’s argument, it resulted in a 

record that is both scientifically sound and adequate. 

For all the foregoing reasons, the request to 

reconsider its prior decision and undertake a formal 

rulemaking, evidentiary hearing process, is denied. 

3. Discretion in making an endangerment finding

Peabody Energy argues that whatever discretion EPA may 

have in making an Endangerment Finding, it must justify and 

defend the specific findings of endangerment it actually 
Page 212 of 217

made. More specifically, Peabody Energy argues that EPA did 

not assess the danger as low risk/high magnitude. It found 

instead both a high risk and high magnitude of harm, citing 

the following quotes from the Findings -- “[t]he scientific 

evidence is compelling that elevated concentrations of 

heat-trapping greenhouse gases are the root cause of 

recently observed climate change” and “[m]ost 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,” with “very likely” 

defined as 90-99% probability. Thus, they conclude, EPA 

must now defend its high risk/high harm conclusion, even if 

arguendo it had discretion to make a lower finding of 

endangerment. 

Peabody Energy argues that this distinction between 

the Endangerment Finding that EPA might be authorized to 

make and the Endangerment Finding it actually made is 

crucial in light of the CRU material. Peabody contends that 

even if EPA might still be able to make an Endangerment 

Finding of some kind (a fact that Peabody does not 

concede), that would not justify the Endangerment Finding 

that EPA actually made and would not form a sufficient 

basis to allow EPA to deny the petitions for 

reconsideration. Peabody argues that the regulation that 
Page 213 of 217

EPA ultimately proposes must be guided by the nature and 

extent of the endangerment that EPA has found, because a 

high risk/high magnitude endangerment finding might justify 

one level of regulation, while a different finding might 

justify a different level. Thus, Peabody Energy claims the 

question that EPA must answer at the endangerment phase is 

not just “endangerment, yes or no?,” but specifically what 

type of endangerment. In that context, Peabody Energy 

argues that the revelations in the CRU material mean that 

EPA must reconsider its Endangerment Finding no matter what 

level of legal discretion the Agency has. Peabody Energy 

at IX-6 to 9. 

Peabody Energy vastly oversimplifies the basis for 

EPA’s Endangerment Finding, characterizing it as a simple 

“high risk/high magnitude” decision. With respect to 

existence of climate changes and attribution to 

anthropogenic emissions of greenhouse gases, the 

Administrator concluded that: 

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. 
Page 214 of 217

74 FR at 66523. Based on this, the Administrator 

considered a wide variety of categories of public health 

and welfare that could be affected by the climate changes. 

The Administrator: 

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. 

Id at 66509. For each of these categories the 

Administrator took into account the varying degree of 

certainty of an impact as well as the potential magnitude 

of an impact. She considered both beneficial as well as 

adverse impacts. Id at 66524-537. There was no simple 

“high risk/high magnitude” paradigm. Instead, the 

Administrator was aware that: 
Page 215 of 217

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. 

Id at 66523-24. Instead of the simple approach described 

by Peabody Energy, the Administrator properly exercised her 

judgment by taking into consideration the complexity and 

breadth of the range of risks and harms presented by the 

evidence. 

In this context, Peabody Energy and other petitioners 

focus their arguments and claims almost exclusively on the 

question of the existence of climate change and its 

attribution to anthropogenic emissions of greenhouse gases. 

After considering their claims, EPA is denying the 
Page 216 of 217

petitions to reconsider for the reasons described above. 

They have not provided substantial support for the argument 

that the Endangerment Finding should be revised, and EPA 

continues to find that 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.” 

In sum, contrary to Peabody Energy’s assertion EPA did 

not employ a simplified “high risk/high magnitude” paradigm 

in making the Endangerment Finding. Instead the 

Administrator carefully and comprehensively considered the 

recognized broad range of varying risks and harms across 

multiple sectors of public health and welfare. In 

addition, EPA is not now changing its Endangerment Finding 

or using its discretion under section 202(a) to base it on 

a “lower finding of endangerment”.