COMMENTS OF THE UTILITY AIR REGULATORY GROUP

on the

PROPOSED ENDANGERMENT AND CAUSE

OR CONTRIBUTE FINDINGS FOR GREENHOUSE GASES

UNDER SECTION 202(a) OF THE CLEAN AIR ACT

Docket ID No. EPA-HQ-OAR-2009-0171

HUNTON & WILLIAMS LLP

Norman W. Fichthorn

Allison D. Wood

Aaron M. Flynn

E. Carter Chandler Clements

1900 K Street, N.W.

Washington, D.C. 20006

(202) 955-1500

Counsel for the Utility Air

Regulatory Group

June 23, 2009
i

TABLE OF CONTENTS

I. Executive Summary........................................................................................................ 3

II. Commenters’ Ability To Obtain a Fair Hearing on the Merits of the 

Endangerment Issue Is Undermined by the President’s Announcement of a New 

“National Policy” that Compels an Affirmative Endangerment Finding Under 

CAA Section 202(a)(1). .................................................................................................. 9

III. EPA’s Stated Rationale Regarding the Statutory Framework and Legal Basis for 

an Affirmative Endangerment Finding Is Inadequate and Fails To Address Critical 

Issues Concerning the Endangerment Criterion’s Preventative Purpose......................... 11

IV. EPA Must Address the Fundamental Threshold Issue of Whether EPA May 

Properly Consider Conditions Caused Largely by Emissions from Outside the 

United States in Making Endangerment and Contribution Findings Under the 

CAA. ............................................................................................................................ 21

V. EPA’s “Technical Support Document for Endangerment and Cause or Contribute 

Findings for Greenhouse Gases Under Section 202(a) of the Clean Air Act” 

Cannot Support a Finding of Endangerment.................................................................. 22

A. The TSD Reflects Fundamentally Flawed Policy Determinations About 

the Information Relevant to an Endangerment Assessment that Skew 

EPA’s Presentation of and Conclusions Regarding the Science.......................... 23

1. Exclusion of Adaptation Considerations................................................. 23

2. Commingling GHG Effects and Non-GHG Effects................................ 28

B. The TSD and the Proposed Endangerment Finding Rely on Sources of 

Scientific Information that Do Not Adequately Address the Issues 

Relevant Under the CAA................................................................................... 30

C. Conclusions in the Proposed Endangerment Finding Are Unclear and 

Must Be Revised. .............................................................................................. 38

D. Scientific Conclusions Stated in the TSD and Relied on by the 

Administrator Are Incorrect............................................................................... 42

1. GHG Emissions..................................................................................... 43

2. Observed and Projected Effects of GHG Concentrations........................ 50

a. Temperature Trends and Modeling ............................................. 50

b. Precipitation ............................................................................... 58

c. Sea Level Rise and Sea Ice......................................................... 59

d. Ocean Acidification.................................................................... 62
ii

e. Physical and Biological Systems ................................................ 62

f. Extreme Events.......................................................................... 66

g. “Abrupt” Climate Change........................................................... 69

h. Ozone and Air Pollution............................................................. 70

3. Effects on Public Health and Welfare..................................................... 73

a. Human Health ............................................................................ 73

b. Ozone and Air Quality................................................................ 80

c. Food Production and Agriculture................................................ 81

d. Forestry...................................................................................... 83

e. Water Resources......................................................................... 86

f. Sea Level Rise and Coastal Areas............................................... 88

g. Energy, Infrastructure, and Settlements ...................................... 89

h. Ecosystems and Wildlife ............................................................ 92

4. International Impacts ............................................................................. 94

VI. The Proposed Endangerment Finding and the TSD Fail To Comply with the Data 

Quality Act. .................................................................................................................. 96

A. Inadequate Peer Review .................................................................................. 100

B. Lack of Transparency...................................................................................... 101

C. Failure To Use Best Available Science ............................................................ 104

VII. EPA Has Not Presented a Proper Contribution Analysis for Public Comment. ............ 106

VIII. If EPA Decides To Promulgate Final Motor Vehicle GHG Rules, Regulation of 

Many Previously Unregulated Sources Will Result. .................................................... 107

IX. A Final Endangerment Finding with Respect to GHGs Under Section 202(a) of 

the CAA Would Not Satisfy the Prerequisites for Listing GHGs as Criteria Air 

Pollutants Under Section 108 of the Act...................................................................... 113

X. A Final Endangerment Finding for GHGs Under Section 202(a) of the CAA 

Would Not Satisfy the Criteria Necessary To Take Any Action Under Section 115 

of the Act.................................................................................................................... 117

XI. Conclusion.................................................................................................................. 118
1

COMMENTS OF THE UTILITY AIR REGULATORY GROUP

on the

PROPOSED ENDANGERMENT AND CAUSE OR CONTRIBUTE

FINDINGS FOR GREENHOUSE GASES UNDER

SECTION 202(a) OF THE CLEAN AIR ACT

Docket ID No. EPA-HQ-OAR-2009-0171

June 23, 2009

______________________________________________________________________________

The Utility Air Regulatory Group (“UARG”) submits the following comments on the 

Proposed Endangerment and Cause or Contribute Findings for Greenhouse Gases Under Section 

202(a) of the Clean Air Act (“Proposed Endangerment Finding”), which the U.S. Environmental 

Protection Agency (“EPA” or “Agency”) published for public comment on April 24, 2009. 74 

Fed. Reg. 18886 (April 24, 2009). UARG is a voluntary, not-for-profit group of electric 

generating companies and organizations and four national trade associations (the Edison Electric 

Institute, the National Rural Electric Cooperative Association, the American Public Power 

Association, and the National Mining Association). UARG’s purpose is to participate 

collectively on behalf of its members in EPA’s rulemakings and other proceedings under the 

Clean Air Act (“CAA” or “Act”) that affect the interests of electric generators and in litigation 

arising from those proceedings. UARG members would be significantly affected by any 

decisions EPA may make concerning the regulation of greenhouse gases (“GHGs”) under the 

existing provisions of the CAA. UARG appreciates the opportunity to comment on the Proposed 

Endangerment Finding and emphasizes that the issues raised by the potential regulation of GHGs 

under the Act are critical to its members as well as to the public and the business community 

generally.

UARG previously submitted extensive comments to EPA on its Advance Notice of 

Proposed Rulemaking Regarding Regulating Greenhouse Gas Emissions Under the Clean Air
2

Act (“ANPR”), which the Agency published on July 30, 2008. 73 Fed. Reg. 44354. In the 

ANPR, EPA sought comment on a broad array of issues relevant to EPA’s possible regulation of 

GHGs under the CAA. In particular, EPA noted that “[t]he potential regulation of greenhouse 

gases under any portion of the Clean Air Act could result in an unprecedented expansion of EPA 

authority that would have a profound effect on virtually every sector of the economy and touch 

every household in the land.” Id. at 44355/1. In the Proposed Endangerment Finding, EPA 

specifically requested that commenters “submit to the docket for today’s action any comments 

they want EPA to consider as it makes a decision on this proposed determination.” 74 Fed. Reg. 

at 18893 n.15. As a result, UARG’s ANPR comments are attached to the present comments as 

Attachment A and should be treated as part of these comments. For convenience, UARG’s 

comments are here referred to as “UARG ANPR Comments.”

UARG notes that, on June 9, 2009, it submitted, through its counsel, a request for a 60-

day extension of the public comment period in this rulemaking. See EPA-HQ-OAR-2009-0171-

2643 (June 9, 2009) (“UARG Letter”). UARG’s letter requested an extension “[b]ecause of the 

importance of this rulemaking and the complex nature of many of the issues addressed in the 

Endangerment Proposal and the accompanying Technical Support Document.” Id. UARG 

observed that “[t]he additional time would allow commenters to submit more detailed 

information that should assist EPA in its decision in this important matter.” Id. UARG added 

that no deadline or other specific time constraints would preclude an extension:

[A]s EPA has acknowledged, no legal deadline applies to this rulemaking, and 

EPA has not announced an intended date for final action. See, e.g., EPA, Spring 

2009 Regulatory Agenda, at 44 (May 11, 2009). In addition, the Agency has not 

yet proposed for public comment any motor vehicle emission standards that 

would be based on any final findings of endangerment and contribution. Thus, a 

60-day extension of the comment period on the Endangerment Proposal would 

neither interfere with any deadline nor delay any standard-setting.
3

Id. EPA responded to UARG’s letter on June 18, 2009, by denying an extension of any length, 

despite the absence of any rulemaking deadline or other timing constraint and without addressing 

UARG’s argument on that point. In the following comments, UARG describes what it believes 

to be the most critical deficiencies in the Proposed Endangerment Finding and in EPA’s 

“Technical Support Document for Endangerment and Cause or Contribute Findings for 

Greenhouse Gases under Section 202(a) of the Clean Air Act” (“TSD”). EPA’s unwarranted

refusal to extend the comment deadline, however, has limited the ability of UARG (and others) 

to submit additional comments and other information that would assist in the development of an 

appropriate outcome in this proceeding.

I. Executive Summary

UARG has great concern about the Proposed Endangerment Finding and the prospect that 

GHG emissions will be regulated under the CAA. Our comments on the Proposed 

Endangerment Finding focus on the following key issues:

· This action is unlawful because the outcome is preordained. The integrity of this 

proposed action is compromised by the apparent fact that the President and EPA already have 

definitively concluded that the Agency must make an affirmative endangerment finding 

under section 202(a)(1) for GHG emissions to allow implementation of a new national policy 

announced by the President on May 19, 2009.

· The asserted legal basis is insufficient. EPA provides a wholly inadequate explanation and 

assessment of the key CAA provisions that purportedly authorize and justify the Proposed 

Endangerment Finding.

· The scientific and factual basis that EPA has presented for the Proposed Endangerment 

Finding is inadequate and incomplete. For example, the Administrator unlawfully defers 

to the judgment of the Intergovernmental Panel on Climate Change (“IPCC”) rather than 

formulating her own assessment of the facts.

· The contribution analysis is misdirected. Among other things, EPA’s analysis incorrectly 

assumes that GHG emissions from all motor vehicles are a suitable surrogate for emissions 

from new motor vehicles, which are the only vehicles that EPA is potentially authorized to 

regulate under section 202(a)(1).
4

· The Agency has unreasonably failed to consider the full consequences of making an 

endangerment finding and of regulating new motor vehicle’s GHG emissions. EPA 

cannot put on blinders and willfully ignore such compelling issues as the potential

applicability of the Act’s Prevention of Significant Deterioration (“PSD”) requirements to 

GHGs and arguments that may be raised based on a section 202(a)(1) endangerment finding 

in the context of other CAA provisions, such as sections 108 and 115, that include an 

endangerment criterion.

As section II of these comments discusses, less than a month after EPA published the 

Proposed Endangerment Finding, the President on May 19, 2009, announced what the White 

House called “a new national policy” to “reduc[e] greenhouse gas pollution for all new cars and 

trucks sold in the United States.” White House Press Release, “President Obama Announces 

National Fuel Efficiency Policy” (May 19, 2009). The President’s new national policy requires 

the promulgation by EPA of GHG emission standards under section 202 of the CAA in 

conjunction with the establishment by the Department of Transportation (“DOT”) of comparable 

national fuel economy standards for vehicles under the Energy Policy and Conservation Act

(“EPCA”).

This Presidential announcement effectively set the course for EPA with respect to its 

decision whether to control GHG emissions from vehicles under section 202. The only real 

questions left to EPA concern certain details of how – but not whether – to control those 

emissions under section 202. See generally EPA and DOT, Notice of Upcoming Joint

Rulemaking To Establish Vehicle GHG Emissions and CAFE Standards, 74 Fed. Reg. 24007 

(May 22, 2009) (“Joint Rulemaking Notice”). Promulgation by EPA of a final affirmative 

endangerment finding, of course, is a necessary step for EPA to regulate under section 202 in 

fulfillment of the President’s policy. These circumstances undermine EPA’s ability to provide 

anything remotely approaching an objective consideration of, and legally adequate response to, 
5

rulemaking comments on the Proposed Endangerment Finding that question or rebut the 

Agency’s asserted basis for an affirmative endangerment finding.

Section III of these comments addresses the inadequacy of EPA’s rationale for its 

Proposed Endangerment Finding and its failure to address critical issues concerning the 

endangerment criterion’s purpose of preventing harm. The CAA and its endangerment 

provisions do not call for “regulation for regulation’s sake” but for regulation where it can be 

shown to achieve the statutory objective of preventing damage. As stated in 1977 legislative 

history quoted by EPA, the effect of the CAA’s endangerment criterion is “[t]o emphasize the 

preventive or precautionary nature of the Act, i.e., to assure that regulatory action can effectively

prevent harm before it occurs.” 74 Fed. Reg. at 18891 n.8 (emphasis added). The Agency 

inexplicably (and inadequately) attempts to refute this fundamental point in the Proposed 

Endangerment Finding. In particular, EPA states its disagreement

with comments that argue the Administrator cannot make a positive 

endangerment or contribution determination unless the emissions reductions 

required by the resulting standards would “effectively mitigate” or “fruitfully

attack” the impacts underlying the endangerment determination. . . . [S]uch an 

approach fails to appreciate the holistic approach that Congress adopted in [the] 

1977 [amendments to the CAA].

Id. at 18893/1.

EPA does not dispute that the “fruitfully attack” phrase comes directly from the decision 

of the U.S. Court of Appeals for the District of Columbia Circuit in the seminal case addressing 

the CAA endangerment criteria, Ethyl Co. v. EPA, 541 F.2d 1, 31 n.62 (D.C. Cir. 1976) (en 

banc). Indeed, EPA characterizes Ethyl as providing the conceptual foundation for the 1977 

statutory amendments to the endangerment provisions that the Agency cites. 74 Fed. Reg. at

18891/2. The point of the “fruitfully attack” language and other quoted passages from Ethyl, of

course, is that “the preventive or precautionary nature of the CAA” that EPA ostensibly 
6

recognizes in the CAA’s endangerment provisions, id. at 18891/3 n.8, calls for regulatory action 

where that action promises to avert the threatened harm. Yet, while failing to provide any 

meaningful explanation of its “holistic approach” theory, EPA fails to show that the 

contemplated regulation resulting from its Proposed Endangerment Finding would prevent at 

least a substantial part of the danger from the global climate change at which the regulation 

ostensibly is aimed.

As Section IV of these comments discusses, EPA also has failed to address the threshold 

issue of whether EPA, in making its proposed findings, properly may consider conditions caused 

largely by emissions from non-U.S. sources that are inherently beyond the scope of U.S. 

regulatory authority. This failure to address a central issue in the proceeding constitutes a critical 

procedural flaw. On the merits, EPA lacks authority to base an endangerment and cause or 

contribute finding on conditions predominantly attributed to non-U.S. sources.

Section V below addresses EPA’s discussion of the science. EPA bases the Proposed 

Endangerment Finding on numerous alleged scientific grounds. The discussion of the science in

the Proposed Endangerment Finding, however, is woefully incomplete and the Agency’s 

conclusions are simultaneously overbroad and, at times, impenetrably vague. These 

shortcomings render the basis for EPA’s policy judgments unsound and require significant 

revisions and enhancements before EPA could proceed in this rulemaking.

Further, EPA bases its proposed scientific judgments on the TSD, which is an inaccurate 

and inadequate assessment of the current state of climate-related science. This document also

would have to be substantially revised if EPA is to proceed further with its proposal to make an 

endangerment finding. The TSD: (1) reflects fundamentally flawed policy determinations about 

the relevant information that skew EPA’s presentation of the science; (2) relies on sources of 
7

information that do not adequately address the scientific issues relevant under the CAA; 

(3) contains improper and inaccurate characterizations of the conclusions that can reasonably be 

drawn from the scientific studies and assessments it cites; and (4) ignores important scientific 

information that undermines EPA’s stated conclusions regarding the negative and positive 

impacts of climate change, including representations concerning the import of substantial 

uncertainties in the scientific record. A wide range of flaws identified in these comments on the 

TSD are reflected in the Proposed Endangerment Finding as well. Moreover, as Section VI of 

these comments details, the serious shortcomings of the Proposed Endangerment Finding and the 

TSD constitute violations of the Data Quality Act.

Section VII of the comments discusses elements of EPA’s “contribution” analysis under 

section 202(a)(1) of the Act. That analysis should address the contribution of emissions from the 

relevant U.S. sources to total worldwide GHG emissions and atmospheric concentrations. 

Because the stated purpose of this proceeding is to address contributions to what EPA 

characterizes as air pollution that consists of global atmospheric concentrations of certain gases, 

it makes no sense to assess U.S. emissions of the sources to be regulated in relation to all U.S.

emissions, with respect to either a single GHG or all six GHGs in the aggregate. Moreover, the 

relevant emissions to be assessed in the contribution analysis are those from new U.S. motor 

vehicles only, not from all U.S. motor vehicles. The emission percentage that EPA cites (4.3%), 

74 Fed. Reg. at 18906/3, reflects emissions from all section 202(a)(1) sources, not emissions 

from that subset of section 202(a)(1) sources, i.e., new vehicles, that EPA is authorized to 

regulate. Moreover, EPA should further refine the contribution assessment to address that subset

of new section 202(a)(1) sources whose GHG emissions it plans to address through regulation.
8

Section VIII of the comments discusses implications of this proceeding for the PSD and 

Title V programs under the Act. As EPA recognized in the ANPR, “if EPA were to regulate 

greenhouse gas emissions from motor vehicles under the Clean Air Act, then regulation of 

smaller stationary sources that also emit GHGs – such as apartment buildings, large homes, 

schools and hospitals – could also be triggered” through the Act’s PSD program. 73 Fed. Reg. at 

44355/1. The potential for regulation of GHGs under the PSD program presents an enormous 

challenge for EPA and the nation. Similar challenges would be posed under the Title V program.

Sections IX and X address possible arguments that could arise under two CAA provisions 

concerning stationary sources -- sections 108 and 115, respectively -- if EPA makes an 

affirmative endangerment finding for GHGs under section 202(a)(1). Should EPA decide to 

make final the Proposed Endangerment Finding, that finding would not be dispositive with 

regard to section 108, which governs the listing of criteria air pollutants. Section 108 contains 

different language from that in section 202. Unlike section 202(a), sections 108 and 109 of the 

CAA authorize listing of a pollutant as a criteria air pollutant, and regulation of that pollutant 

through NAAQS, for the purpose of addressing any endangerment of the public health or welfare 

that may reasonably be anticipated due to the quantities of the pollutant in the ambient air, i.e., 

the relatively limited portion of the atmosphere to which the general public has access. Thus, 

before the Agency could list any GHGs as criteria air pollutants under section 108 of the Act, it 

would have to determine what, if any, effects on U.S. public health or welfare occur due to the 

presence of GHGs in the ambient air in the United States. The Proposed Endangerment Finding

and TSD do not address this matter. Indeed, the absence of information regarding the effects of 

GHGs on public health and welfare due to their presence in the U.S. ambient air could, in fact, 

provide at least one reason for the Administrator to conclude that she has no “plans to issue air 
9

quality criteria” for GHGs – which also is a prerequisite for listing under section 108. CAA § 

108(a)(1)(C). Likewise, for reasons discussed in Section X below, if the Administrator makes a 

final endangerment finding in the present proceeding, that finding would not satisfy the 

requirements of section 115, the Act’s provision addressing international pollution.

II. Commenters’ Ability To Obtain a Fair Hearing on the Merits of the Endangerment 

Issue Is Undermined by the President’s Announcement of a New “National Policy” 

that Compels an Affirmative Endangerment Finding Under CAA Section 202(a)(1). 

Less than a month after EPA published the Proposed Endangerment Finding, the 

President on May 19, 2009, announced what the White House called “a new national policy” to 

“reduc[e] greenhouse gas pollution for all new cars and trucks sold in the United States.” White 

House Office of the Press Secretary, Press Release, “President Obama Announces National Fuel 

Efficiency Policy” (May 19, 2009). The President’s new national policy requires the 

promulgation by EPA of GHG emission standards under section 202 of the CAA in conjunction 

with the establishment by DOT of comparable national fuel economy standards for vehicles 

under EPCA. The White House and Administrator Jackson, who appeared with the President at 

his announcement of the new policy, presented the decision as the resolution of controversies -- a 

resolution, brokered by the President and his staff, to which certain “stakeholders” reportedly

had agreed after closed-door discussions -- about whether and how to control new motor 

vehicles’ GHG emissions. The White House and the Administrator made the announcement of 

this “national policy on fuel economy standards and greenhouse gas emissions” in terms that 

indicate that the Executive Branch deems the present endangerment rulemaking little more than a 

formality and a final endangerment finding essentially a fait accompli:

This groundbreaking policy delivers on the President’s commitment to enact more 

stringent fuel economy standards and represents an unprecedented collaboration 

between the Department of Transportation (DOT), the Environmental Protection 

Agency (EPA), the world’s largest auto manufacturers, the United Auto Workers, 
10

leaders in the environmental community, the State of California, and other state 

governments.

“The President brought all stakeholders to the table and came up with a plan to 

help the auto industry, safeguard consumers, and protect human health and the 

environment for all Americans,” said EPA Administrator Lisa P. Jackson. “A 

supposedly ‘unsolvable’ problem was solved by unprecedented partnerships. As a 

result, we will keep Americans healthier, cut tons of pollution from the air we 

breathe, and make a lasting down payment on cutting our greenhouse gas 

emissions.”

Id. (emphases added). The President himself referred to “this rule” -- “this new national 

standard” -- as an accomplished fact; he stated, for example, that “the Department of 

Transportation and EPA will adopt the same rule.”1The White House Office of the Press 

Secretary, “Remarks by the President on National Fuel Efficiency Standards,” Rose Garden, 

May 19, 2009 (emphasis added).

In short, the President’s Rose Garden announcement -- a major news event that 

commanded front-page headlines and led television news programs throughout the country --

establishes a new national policy that requires EPA to adopt section 202 GHG standards. Thus, 

the outcome of the present proceeding appears to be preordained and therefore, necessarily, the 

merits of the endangerment issue to be prejudged.

Whatever the arguments may be for this new national policy, its announcement by the 

President effectively sets the course for EPA with respect to its decision whether to control GHG 

1

The fact that, as the President stated, DOT “will” adopt “the same rule” as EPA will adopt 

makes EPA’s prospective section 202 emission standards -- and its section 202(a)(1) 

endangerment finding -- unnecessary to the achievement of the GHG emission reductions that 

would be based on that finding. As discussed in section III of these comments, this fact 

undermines any claim that the Proposed Endangerment Finding is grounded in the preventative 

principle on which section 202(a)(1) is based. In other words, even assuming that the emission 

reductions that would occur under the contemplated section 202 standards would prevent any 

appreciable part of the endangerment EPA proposes to find (an implausible assumption that EPA 

has not even attempted to support), those emission reductions would, due to the DOT standards, 

occur even in the absence of any section 202 regulation.
11

emissions from vehicles under section 202. In essence, the only real questions left to EPA 

concern certain details of how -- but not whether -- to regulate those emissions under section 

202. See generally Joint Rulemaking Notice, 74 Fed. Reg. 24007 (discussing details of ways to 

structure section 202 standards in conjunction with fuel efficiency standards). Promulgation by 

EPA of a final affirmative endangerment finding, of course, is a necessary step for EPA to take 

in order to regulate under section 202 in fulfillment of the President’s policy. These 

circumstances seriously undermine EPA’s ability to provide anything remotely approaching an 

objective consideration of, and a legally adequate response to, rulemaking comments that 

question or rebut the Agency’s asserted basis for an affirmative endangerment finding.2

III. EPA’s Stated Rationale Regarding the Statutory Framework and Legal Basis for an 

Affirmative Endangerment Finding Is Inadequate and Fails To Address Critical 

Issues Concerning the Endangerment Criterion’s Preventative Purpose. 

Given the volume and range of comments that EPA received on legal issues raised by the 

ANPR,3and given the enormous importance of the present proposal, UARG expected a much 

more substantial treatment by EPA of the legal issues implicated by the Proposed Endangerment 

Finding than appears in the proposed rule. Perhaps the limited nature of EPA’s discussion of 

relevant legal issues here is explained by its implicit reliance on the ANPR to supplement EPA’s 

present statement of basis for purposes of public notice. See 74 Fed. Reg. at 18893 n.15. EPA 

has, however, only attempted “to respond to a few key [ANPR] comments related to the test that 

2

See 74 Fed. Reg. at 18889 n.4 (applying the procedural requirements of CAA section 307(d) to 

this proceeding). If EPA now believes, notwithstanding the President’s directive that the Agency 

regulate GHG emissions under section 202, that it can provide fully objective consideration, on 

the merits, of all comments in this proceeding, the Agency should explain the basis for that belief 

in a supplemental notice of proposed rulemaking. 

3 As noted above, UARG includes here its comments on the ANPR, filing them in this 

rulemaking docket for EPA’s review and response. 
12

some stakeholders believe guides the Administrator when undertaking an endangerment analysis 

and cause or contribute evaluation.” Id. EPA’s attempted response is not only limited but also

inadequate in key respects.

EPA expresses its disagreement with ANPR comments, presumably including UARG’s 

(see UARG ANPR Comments at 32-33), that address the preventative, or precautionary, test 

established by CAA provisions such as section 202(a)(1). EPA states its disagreement

with comments that argue the Administrator cannot make a positive 

endangerment or contribution determination unless the emissions reductions 

required by the resulting standards would “effectively mitigate” or “fruitfully

attack” the impacts underlying the endangerment determination. . . . [S]uch an 

approach fails to appreciate the holistic approach that Congress adopted in [the]

1977 [amendments to the CAA].

Id. at 18893/1. 

Yet EPA does not dispute that the “fruitfully attack” phrase quoted in UARG’s ANPR 

comments comes directly from the decision of the U.S. Court of Appeals for the District of 

Columbia Circuit in the seminal case addressing the CAA endangerment criteria, Ethyl Co. v. 

EPA, 541 F.2d 1, 31 n.62 (D.C. Cir. 1976) (en banc). Indeed, EPA characterizes the Ethyl

decision as providing the conceptual foundation for the 1977 statutory amendments to the 

endangerment provisions that the Agency cites. 74 Fed. Reg. at 18891/2. The point of the 

“fruitfully attack” language and other quoted passages from Ethyl, of course, is that “the 

preventive or precautionary nature of the CAA” that EPA ostensibly recognizes in the CAA’s 

endangerment provisions, id. at 18891/3 & n.8, calls for regulatory action where that action 

promises to avert the threatened harm. See also id. at 18890/2 (statutory purpose is to “prevent 

harm”); id. at 18890/3 (same); id. at 18891/1 (same). In other words, the CAA and its 

endangerment provisions do not call for “regulation for regulation’s sake” but for regulation 

where it can be shown to achieve the statutory objective of preventing damage. As stated in 
13

1977 legislative history quoted by EPA here, the effect of the CAA’s endangerment criterion is 

“[t]o emphasize the preventive or precautionary nature of the Act, i.e., to assure that regulatory 

action can effectively prevent harm before it occurs.” Id. at 18891 n.8 (emphasis added).

EPA never explains what it means by the “holistic approach” that it says Congress

adopted in the 1977 CAA amendments and how that supposed approach should apply here; it 

says little more on that point than that Congress directed EPA to “consider the whole picture.”4

Id. at 18893/2. Instead, EPA sets up a strawman: The Agency implies that commenters such as 

UARG suggest that regulatory action under the endangerment criterion can be justified only if 

that action “alone can solve the problem.” Id. (emphases added). As EPA characterizes this 

putative “all or nothing” position, commenters’ “various narrow approaches to the endangerment 

and cause or contribute criteria . . . would preclude the Administrator from making a positive 

finding for any complex pollution problem that cannot be solved by one regulatory action alone.” 

Id. But that does not represent at all the view advanced in UARG’s comments. To the contrary, 

as explained in its ANPR comments (included here as Attachment A), UARG observes that the 

facts that justified “endangerment” regulation in Ethyl illustrate the principle that must guide 

EPA here:

In the case of the lead in motor vehicle fuels addressed in Ethyl, . . . there were 

strong reasons for EPA to believe that regulation of the lead in fuels would 

prevent at least a substantial part of the danger to public health posed by human 

exposure to that air pollutant. See, e.g., Ethyl, 541 F.2d at 31 (The Administrator 

“determined that absorption of lead automobile emissions, when added to all other 

human exposure to lead, raises the body lead burden to a level that will endanger 

health. He realized that lead automobile emissions were, far and away, the most 

readily reduced significant source of environmental lead.”). 

4 Resort to the dictionary is of limited help here. See, e.g., Funk & Wagnalls Standard College 

Dictionary (1977) (defining “holism” as “[t]he theory that a material object, especially a living 

organism, has a reality other and greater than the sum of its constituent parts”). 
14

UARG ANPR Comments at 32 (emphasis added). It was for this reason that the Ethyl court said 

the emission control regulation that would be based on EPA’s endangerment finding can 

“fruitfully ... attack” -- not necessarily solve by itself, but meaningfully and substantially reduce

-- the environmental and public health danger at hand. See, e.g., Ethyl, 541 F.2d at 8, 9 (“lead 

particulate emissions from gasoline engines [i.e., the emissions that would be regulated] account 

for approximately 90 percent of the lead in our air”; these “easily . . . controllable” emissions 

“can be simply eliminated by removing lead from gasoline”).

Thus, it is not a valid defense of the Proposed Endangerment Finding for EPA to make 

the (presumably) undisputed point that no single section 202 GHG emission standard (and no 

other individual CAA emission standard) can, on its own, “solve” global climate change or 

“solve” the array of problems EPA says are associated with that global change. 74 Fed. Reg. at 

18893/2. The CAA does not necessarily set the bar so high. But EPA here has fallen short of a 

much lower hurdle that it must clear to produce a defensible rationale for an affirmative 

endangerment finding: It has failed to show -- indeed, it has failed even to attempt to show --

that the contemplated regulation resulting from such a finding would prevent at least a 

substantial part of the danger from the global climate change at which the regulation ostensibly is 

aimed.5

Given the importance of this issue in administration of the CAA’s endangerment 

provisions, if EPA believes that a basis exists to conclude that regulation of GHG emissions from 

5

EPA acknowledges in the Proposed Endangerment Finding that, in applying the endangerment 

and contribution criteria in section 202(a)(1), it is appropriate to consider whether meaningful 

emission reductions would occur as a result of making a finding under that provision. See, e.g., 

74 Fed. Reg. at 18908/1 (citing the asserted availability of “valuable reductions” in methane 

emission levels as a “primary” reason that methane emissions should be the subject of a section 

202(a)(1) finding).
15

new U.S. motor vehicles would meaningfully reduce the endangerment it proposes to find, then 

EPA should publish for public comment a supplemental notice providing that basis. Any 

assessment of this issue, however, would have to take into account the degree of contribution to 

the asserted endangerment that section 202 regulation actually would address. In that regard, 

EPA would need to begin by refining its “contribution” analysis in the Proposed Endangerment 

Finding to address issues such as those described below. 

In the Proposed Endangerment Finding, EPA presents information on the contribution to 

total GHG emissions6of “all of the section 202(a) source categories,” meaning passenger cars, 

light-duty trucks, motorcycles, buses, and medium/heavy-duty trucks. Id. at 18905/3. EPA has 

failed to present information, however, on the part of the contribution that is attributable to the 

statutorily covered sources, i.e., the contribution of emissions from that portion of “the section 

202(a) source categories” that constitutes “new” motor vehicles within those source categories. 

CAA § 202(a)(1). Section 202(a)(1) plainly gives EPA no authority to impose additional 

emission control regulations on, or to make an endangerment finding concerning, existing 

vehicles. Thus, for example, the maximum degree of any global climate change endangerment 

that might be removed or prevented by section 202(a)(1) standards would be far less than that 

represented by the 4.3% of global GHG emissions that EPA attributes to all section 202(a) 

sources, both existing and new. See 74 Fed. Reg. at 18906/3.

Moreover, since publication of the Proposed Endangerment Finding, EPA has explained 

that only a subset of even the new-source subcategory of section 202(a) sources would in fact be 

6 As discussed in section VII below, the contribution to total emissions must be assessed in terms 

of contribution to total global emissions, not in terms of contribution to total U.S. emissions. 

That is because any global climate change endangerment found by EPA would result, in the 

aggregate, from global atmospheric concentrations of GHGs, which are influenced in an 

undifferentiated way by emissions from all sources of all types in all parts of the world.
16

regulated under section 202(a) as a result of a final endangerment finding. In the May 22 Joint

Rulemaking Notice, EPA states that it intends, based on its anticipated section 202(a)(1) 

endangerment finding, to propose GHG emission standards under section 202(a) for “passenger 

cars, light-duty trucks, and medium-duty passenger vehicles (light-duty vehicles) built in model 

years 2012 through 2016.” 74 Fed. Reg. at 24007/3. Thus, the subcategory of new section 

202(a) sources that EPA is targeting for regulation includes some, but not all, types of U.S. 

vehicles built in five specified model years but excludes certain classes of “section 202(a) source

categories” altogether, including motorcycles, buses, and medium/heavy-duty trucks. Compare

74 Fed. Reg. at 18905/3 (listing, in the Proposed Endangerment Finding, “Section 202(a) source 

categories”) with 74 Fed. Reg. at 24007/3 (describing, in the Joint Rulemaking Notice, the

section 202(a) source categories EPA plans to regulate under section 202(a)). From the 

information EPA has presented, it is unclear what portion of a projected 4.3% total contribution 

to GHG emissions can be attributed to new U.S. “passenger cars, light-duty trucks, and mediumduty passenger vehicles (light-duty vehicles) built in model years 2012 through 2016” -- as 

opposed to the far larger collection of sources, including existing motor vehicles of all sorts and 

new medium- and heavy-duty trucks, buses, and motorcycles, that EPA’s Proposed 

Endangerment Finding characterizes as the “section 202(a) source categories.” 74 Fed. Reg. at 

18905/3. Thus, the 4.3% contribution percentage cited by EPA greatly overstates the 

contribution to total GHG atmospheric concentrations that section 202(a) regulation would 

address. 

Furthermore, even if one determined what part of the asserted 4.3% contribution reflects 

emissions from the limited subset of section 202(a) sources that EPA plans to regulate, that lower 

amount would still be far higher than the emissions that would be controlled by the section 
17

202(a) regulation -- which is the legally relevant portion of the emissions. EPA’s section 202(a) 

emission standards obviously will not eliminate anything remotely approaching all GHG 

emissions from the subset of vehicles that are regulated under those standards. 

EPA intends to adopt a “generally linear phase-in from [model year] 2012 through to 

model year 2016,” leading to an average limit of 250 grams of carbon dioxide (“CO2”) per mile 

in the last of those five model years. 74 Fed. Reg. at 24008/3. Given this phase-in approach, 

emissions from regulated vehicles built in the earlier years will have higher CO2 emissions than 

those built in the later years. EPA’s planned approach involves a gradual reduction from what 

might be considered an emission baseline of 325.5 grams per mile in model year 2011. See 74 

Fed. Reg. 14196, 14412/2 (Mar. 30, 2009) (final fuel economy standards for model year 2011 

passenger cars and light trucks). That amounts to approximately an eventual 23% reduction in 

the emission rate, phased in slowly over a period of six model years and, of course, still leaving 

77% of the baseline emissions. The ability of the Proposed Endangerment Finding to prevent or 

reduce asserted harms should be evaluated in respect to the emission reduction actually 

contemplated, which is far less than all emissions from the subcategories of new sources to be 

regulated. 

In evaluating the potential of the section 202(a) regulations to prevent or reduce the 

asserted endangerment, moreover, EPA would need to address the fact that individual 

consumers, businesses, and other vehicle purchasers can be expected to continue to operate

existing vehicles to a greater extent than would otherwise be the case in order to avoid or defer 

paying the increased prices for new vehicles that will have to be manufactured, at greater cost, to 

meet more demanding emission and fuel economy standards. As a result of the expected 

emission and fuel economy standards, “EPA estimates an average increased cost of about $1,300 
18

per vehicle in 2016 compared to today’s vehicles.” EPA Office of Transportation and Air 

Quality, “Regulatory Announcement: EPA Will Propose Historic Greenhouse Gas Emissions 

Standards for Light-Duty Vehicles,” at 1, EPA-420-F-09-028 (May 2009). Although EPA 

believes fuel savings over time would offset the higher cost, see id. at 1-2, it is unclear that that 

fact, even if correct, would overcome vehicle purchasers’ reluctance to pay -- or, in many cases, 

their inability to afford -- a higher upfront vehicle price. The disincentive of higher vehicle 

prices, and the resulting retention of existing vehicles that are not subject to GHG emission 

controls and are less fuel efficient, would further limit the emission reductions that would result 

from EPA’s promulgation of a final endangerment finding. See, e.g., Elizabeth Shogren, 

“Environmentalists Say Obama’s Auto Plan Is a Start,” National Public Radio Transcript (May 

20, 2009) (“NPR Transcript”) (“Some experts say Obama’s proposal would drive up the cost of 

new cars -- by $1,300, according to the White House -- and make people more likely to hold on 

to their old cars. ‘Those older cars tend to be of lower fuel efficiency and significantly more 

polluting, so there’s a counterproductive effect,’ says Robert Stavins, director of Harvard 

University’s environmental economics program.”); see also National Research Council, 

Effectiveness and Impact of Corporate Fuel Economy (CAFE) Standards, National Academy 

Press (2002) (finding increased fuel efficiency leads to additional driving, which increases 

vehicle emissions, and substantially adds to traffic-related mortality).

Moreover, any assumption that overall GHG emission reductions will result from any

shift that might occur to vehicles with lower GHG emissions per mile rests on the implausible 

premise that total vehicle miles traveled will not increase due to consumers’ recognition of the 

per-mile fuel-cost reduction that the White House argues will offset higher vehicle prices. 

National Public Radio (“NPR”) reports that Harvard Professor Robert N. Stavins “points to 
19

another shortcoming of the fuel economy [and the tandem GHG] standards. ‘Once you’ve 

bought the car, it doesn’t provide an incentive to drive it any less,’ he says. ‘In fact, by 

increasing fuel efficiency, it actually provides an incentive to use the car more because it lowers 

the operating cost.’” NPR Transcript. Similarly, according to NPR, David Friedman, the 

Research Director of the Union of Concerned Scientists’ Clean Vehicles Program and a 

supporter of the President’s plan to impose GHG vehicle emission controls, “concedes that total 

greenhouse gas pollution from vehicles might not be any less 10 years from now because of 

more motorists on the road driving more miles.” Id.

The factors described above call into question any conclusion that EPA might make that 

an affirmative endangerment finding and resulting section 202(a) standards would have any 

appreciable effect, let alone a substantial effect, in preventing or reducing any danger from 

global climate change. Yet these factors are among those that EPA fails to examine in the 

Proposed Endangerment Finding. If EPA intends to proceed with this rulemaking, it must assess 

these factors objectively, and not merely to support a predetermined regulatory outcome, and 

must then provide a discussion of them in a supplemental proposal for public review and 

comment. 

EPA, however, may already have concluded that making final the Proposed 

Endangerment Finding would, in fact, have no meaningful effect in preventing or reducing any

endangerment from the section 202(a) sources that it intends to regulate. For example, in an 

interview broadcast on May 20, 2009, the day after announcement of the President’s new 

national policy, Administrator Jackson said, referring to the planned section 202(a) standards, 
20

that “[t]his action alone -- I don’t want to mislead anyone -- is not going to change global 

temperatures.”

7

Id. (emphasis added).

Even if section 202(a) standards would produce emission reductions that would 

meaningfully reduce the threat EPA would purport to address through a final endangerment 

finding, the Agency’s Proposed Endangerment Finding fails to address questions concerning 

whether some (or all) of such emission reductions would occur anyway. One of the central 

tenets of the new national policy announced on May 19 is that EPA and DOT will establish “a 

harmonized and consistent” set of regulations for vehicle GHG emissions and fuel efficiency, 

leading to “a single light-duty national fleet that would satisfy all requirements under both 

programs.” 74 Fed. Reg. at 24007/3; see also id. at 24009/3 (stating the program’s goal of 

“providing regulatory compatibility that allows auto manufacturers to build a single national 

light-duty fleet that would comply with both the GHG and the CAFE standards”). Accordingly, 

there is no reason to believe that section 202(a) regulation -- or the accompanying EPA 

endangerment finding -- is needed to accomplish any emission reductions that the coordinated 

program may yield. For all practical purposes, any such reductions will occur due to the CAFE

standards even in the absence of any EPA action under section 202(a) of the CAA. Thus, the 

Proposed Endangerment Finding is not necessary -- even if it were otherwise justified -- because 

any contribution to global atmospheric concentrations of GHGs that would be addressed by 

section 202(a) standards will be addressed outside the CAA, by DOT under EPCA.

7 Administrator Jackson is not alone in espousing that view. For instance, Professor Ken 

Caldeira, a climate scientist at Stanford University’s School of Earth Sciences and the Carnegie 

Institution’s Department of Global Ecology, was quoted by NPR as saying that “‘[t]hese 

[emission] cuts are important as an act of political leadership, but these cuts in themselves will 

not produce any significant climate effect.’” NPR Transcript (emphasis added).
21

In sum, EPA’s Proposed Endangerment Finding provides no basis for concluding that the 

purpose of the section 202(a)(1) endangerment criterion would be served by making a final

endangerment finding. Accordingly, if the Agency intends to proceed to final affirmative action 

on the Proposed Endangerment Finding, it would, at a minimum, first have to prepare and 

publish a supplemental notice for public comment that explains what, if any, basis exists for a 

final endangerment finding in light of the preventative purpose of the section 202(a)(1) criterion.

IV. EPA Must Address the Fundamental Threshold Issue of Whether EPA May 

Properly Consider Conditions Caused Largely by Emissions from Outside the 

United States in Making Endangerment and Contribution Findings Under the CAA.

EPA has failed to address one of the most fundamental threshold legal issues underlying 

the Proposed Endangerment Finding -- whether the Agency may consider air emissions and the 

resulting air pollution from sources outside the sovereign authority of the United States in 

making endangerment and contribution findings that establish legally binding obligations for the 

Agency and entities under the CAA. This is a question of first impression that EPA has not 

answered (indeed, has not had to answer) in making any previous CAA endangerment finding. 

As a procedural matter, EPA’s failure to address this key legal issue is a fatal flaw in the 

proposal because it obviously is a question of central relevance to the outcome of this action and 

the public has been deprived of the right to understand EPA’s views on the issue and to provide 

meaningful comments in the context of an Agency articulation of its position.

On the substance of this issue, it is clear that EPA does not have authority under the Act 

to establish domestic rights and legally binding obligations based on environmental conditions 

that are largely attributed to foreign nations and entities that are under the authority of such 

nations (and outside the authority and jurisdiction of EPA and the CAA). To construe the CAA 

otherwise would create the anomalous result that the bulk of the emissions that would cause 

mandatory emissions controls to be prescribed under the CAA would not (and could not) be 
22

subject to those controls because the emissions emanate from foreign sources – which, of course, 

is the very situation presented by GHG emissions and their potential effect on the global climate. 

Just as CAA requirements cannot be enforced against foreign sources of air pollution, domestic 

obligations under the CAA cannot be caused by foreign emissions that are outside CAA 

jurisdiction.

V. EPA’s “Technical Support Document for Endangerment and Cause or Contribute 

Findings for Greenhouse Gases Under Section 202(a) of the Clean Air Act” Cannot 

Support a Finding of Endangerment.

EPA bases the Proposed Endangerment Finding on numerous alleged scientific grounds.

EPA’s discussion of the science in the Proposed Endangerment Finding, however, is woefully 

incomplete, and EPA’s conclusions related to the available scientific evidence are both

overbroad and, at times, impenetrably vague. Given these shortcomings, EPA has not provided 

an adequate basis for an affirmative endangerment finding.

The Administrator bases her proposed scientific judgments on the TSD, which EPA staff 

prepared and is itself an inaccurate and inadequate assessment of the current state of climaterelated science. This document would require substantial revision before the Administrator 

could rely on it for reaching endangerment-related policy conclusions. 

The TSD: (1) reflects fundamentally flawed policy determinations about the relevant 

information, determinations that skew EPA’s presentation of the science; (2) relies on sources of 

information that do not adequately address the scientific issues relevant under the CAA; (3) 

contains improper and inaccurate characterizations of the conclusions that can reasonably be 

drawn from the scientific studies and assessments it cites; and (4) ignores important scientific 

information that undermines EPA’s stated conclusions regarding the negative and positive 

impacts of climate change, including representations concerning the import of substantial 
23

uncertainties in the scientific record. The various flaws identified in the following comments on 

the TSD are reflected in the Proposed Endangerment Finding as well. 

A. The TSD Reflects Fundamentally Flawed Policy Determinations About the 

Information Relevant to an Endangerment Assessment that Skew EPA’s 

Presentation of and Conclusions Regarding the Science. 

EPA states that the TSD’s purpose is “to provide scientific and technical information for 

an endangerment analysis regarding greenhouse gas (GHG) emissions from new motor vehicles 

and engines under section 202(a) of the Clean Air Act.” TSD at 1. The scientific and technical 

information provided in the document, however, is wholly inadequate to support an affirmative 

endangerment finding under the provisions of the Act. This failing results from numerous 

problems detailed in these comments. Some of these flaws stem from unscientific policy 

determinations that, in turn, improperly influence the scope of the information considered in the 

document. These determinations distort EPA’s analysis, resulting in an assessment that is biased 

in favor of a positive endangerment determination. Accordingly, the Administrator’s proposed 

finding is likewise improper, as it is based on incomplete and inaccurate science. Fundamental

flaws in the TSD and Proposed Endangerment Finding include: (1) exclusion of information 

relevant to adaptation; and (2) failure to distinguish between GHG- and non-GHG-related 

climate effects.

1. Exclusion of Adaptation Considerations

Both the TSD and the Proposed Endangerment Finding reflect a proposed conclusion that 

consideration of the effects of adaptation are not appropriate in conducting an endangerment 

analysis. The TSD, for instance, states:

Adaptation to climate change is a key focus area of the climate change research 

community. This document, however, does not focus on adaptation because 

adaptation is essentially a response to any known and/or perceived risks due to 

climate change. Likewise, mitigation measures to reduce GHGs, which could 

also reduce long-term risks, are not addressed. The purpose of this document is to 
24

review the effects of climate change and not to assess any speculative policy or 

societal response to climate change. Adaptation will be mentioned to the extent 

that the impacts projections themselves contain some embedded assumptions 

about future adaptation.

Id. at 2. 

Thus, the Agency has determined, as a matter of policy, to exclude “a key focus area of 

the climate change research community” because it is essentially only a response to climate 

change.8Id. EPA’s position on this issue is illogical and internally inconsistent. Almost every

impact assessed in the TSD is a response to climate change. Animal migrations, additional 

expenditures for energy infrastructure, and even changes in air pollution levels are, at their most 

basic levels, responses to changing climate. Moreover, it is simply unsupportable for EPA to 

assert that adaptation is irrelevant to determining whether endangerment exists or will exist. 

Unless one made an assumption (which would be without foundation) that all changes are 

negative -- and EPA says it has made no such assumption

9

-- the fundamental inquiry of an 

endangerment analysis concerns the type and extent of harm that are believed likely to occur. 

This inquiry cannot proceed in the absence of an examination of the likely impacts of climate 

change, a matter that simply cannot be engaged rationally if the role of adaptation is ignored. In

8

EPA’s posited reasons for distinguishing between “acceptable” and “unacceptable” fields of 

scientific inquiry are particularly unconvincing given that the IPCC deemed it appropriate to 

devote an entire Working Group Report to adaptation and mitigation, wholly ignored in the TSD, 

even as EPA relies almost exclusively on the other IPCC Working Group Reports for the bulk of 

its analysis. Moreover, in a remarkable example of analytical selectivity, EPA states in the 

Proposed Endangerment Finding that “the IPCC North American chapter ... on ... adaptation

and vulnerability covers the U.S. and Canada (not Mexico) and ... the general findings in that 

chapter (drawn from many individual studies for the U.S.) are indeed applicable to U.S. 

conditions.” 74 Fed. Reg. at 18894/2 (emphases added).

9

See, e.g., id. at 18904/1 (“The Administrator’s proposed endangerment finding is based on 

weighing the scientific evidence, considering the uncertainties, and balancing any benefits to 

human health, society, and the environment that may also occur.”).
25

fact, EPA seems to admit this in its statement that “[a]daptation will be mentioned to the extent 

that the impacts projections themselves contain some embedded assumptions about future 

adaptation.”10 Id. (emphasis added). It is irrational and unscientific for EPA to consider a factor 

it acknowledges is relevant only when others, on which the Agency relies, have embedded 

assumptions about this factor in their projections. If adaptation is relevant in that context, it is

equally relevant where EPA itself must perform the assessment. 

Further, adaptation assessment is central to the statutory requirements governing EPA’s 

endangerment inquiry and is not some peripheral or minor consideration that the Agency may 

reasonably disregard. Indeed, the TSD quotes a significant conclusion of the U.S. Climate 

Change Science Program (“CCSP”) indicating that “[t]he United States is certainly capable of 

adapting to the collective impacts of climate change.” Id. at 69 (quoting CCSP (2008b)

(emphasis added)). This conclusion illustrates the fact that adaptation alone could avert what 

might otherwise constitute endangerment in a hypothetical world in which adaptation does not 

occur. EPA’s decision to exclude adaptation considerations from its endangerment assessment 

10 Indeed, in a number of instances, the TSD states that adaptation is a crucial factor in 

determining whether and when negative impacts, and thus (potentially) endangerment, will 

occur. See, e.g., TSD at 69 (“In the absence of effective adaptation, these [mortality and 

morbidity] effects are likely to increase with climate change. Depending on progress in health 

care and access, infrastructure, and technology, climate change could increase the risk of heat 

wave deaths, respiratory illness through exposure to aeroallergens and ozone ... and certain 

diseases.”) (internal citations omitted); id. at 70 (“Estimates of heat-related mortality attributable 

to climate change are reduced but not eliminated when assumptions about acclimatization and 

adaptation are included in models.... In other words, non-climatic factors related to 

demographics will have a significant influence on future heat-related mortality.”) (emphasis 

added); id. at 141 (“Current scientific information does not provide sufficient information to 

assess how effective current and future adaptation options will be at reducing vulnerability to the 

impacts of climate change.”); id. at 142 (“More adaptation will be required to reduce 

vulnerability to climate change. Additional adaptation can potentially reduce, but is never 

expected to completely eliminate[,] vulnerability to current and future climate change.”) (internal 

citations omitted); id. (“A portfolio of adaptation and mitigation measures can diminish the risks 

associated with climate change.”).
26

is, in essence, an arbitrary and unsupportable policy preference for an imagined scenario over 

reasonable scientific projections of actual future conditions. EPA should, therefore, reverse its 

decision to exclude these considerations from the endangerment assessment. Moreover, at the 

very least, it is inappropriate for EPA to omit assessment of adaptation from its analysis of 

climate change impacts in the TSD. See id. at 2 (“This document, however, does not focus on 

adaptation because adaptation is essentially a response to any known and/or perceived risks due 

to climate change.”). A technical support document in this context should present all of the 

information that may be relevant to the question whether public health and welfare will be 

endangered without prejudging what scientific information will be used in making the ultimate 

policy decision. See id. at 1 (“This document itself does not convey any judgment or conclusions 

regarding the two steps of the endangerment finding, as these decisions are ultimately left to the 

Administrator.”).

The Proposed Endangerment Finding itself reflects the TSD’s mistaken approach. See 74 

Fed. Reg. at 18894/2-3 (“[C]limate policy or societal responses to any known or perceived risks 

and impacts to public health or welfare, which may or may not be implemented in the future—

whether through planned adaptation or greenhouse gas mitigation measures—were not explicitly 

assessed in the endangerment analysis.”). EPA says it decided against assessing adaptation

because

the purpose of the endangerment analysis is to assess the risks posed to public 

health and welfare, rather than to estimate how various adaptation and greenhouse 

gas mitigation policies may ameliorate or exacerbate any endangerment that 

exists. Indeed, the presumed need for adaptation and greenhouse gas mitigation 

to occur to avoid, lessen or delay the risks and impacts associated with humaninduced climate change presupposes that there is endangerment to public health 

or welfare.

Id. at 18894/3 (emphasis added). 
27

EPA’s facile rationale that adaptation necessarily presupposes endangerment and thus 

should be excluded from assessment cannot withstand scrutiny. Adaptation to changing 

circumstances occurs constantly in the natural and human environment as a response to any 

number of conditions, as we have known since the time of Darwin, and certainly not all of those 

circumstances have constituted an “endangerment to public health or welfare.” The 

Administrator’s additional argument that she “would not consider, for example, the availability 

of asthma medication in determining whether criteria air pollutants endanger public health,” id.,

while factually accurate, is not a relevant analogy to adaptation in the context of climate change.

The availability of medication to treat the symptoms of a lung function response, and the need to 

medicate to prevent them, is not comparable to evolutionary responses in natural ecosystems or

to changes in human behavior that may prevent welfare or indirect health impacts from ever 

occurring at all. Indeed, in a variety of other settings, EPA has promulgated regulations and 

implemented policies to encourage adaptive responses to what might have otherwise developed 

into adverse public health and welfare impacts.11 Further, the Administrator’s rationale is flatly 

inconsistent with her consideration of “embedded . . . assumptions” regarding adaptation in 

specific instances. See id.

In sum, EPA fails to provide a reasoned analysis for excluding any assessment of 

adaptation effects. The Agency’s notion that the existence of adaptation “presupposes” 

11 For instance, EPA’s guidance related to its Air Quality Index recommends that individuals 

refrain from strenuous activities when air pollution reaches certain levels in order to avoid public 

health risks. See AirNow Partner Agencies, TV Weather -Air Quality Guide for Particle 

Pollution-Air Quality Index (AQI) At-A-Glance Messages, available at http://airnow.gov/index. 

cfm?action=tvweather.ataglance. Similarly, EPA’s Sunwise Program recommends a variety of 

behavioral responses to limit or avoid public health risks associated with sun exposure, including 

limiting time spent outdoors and use of sunscreen. See EPA, Sun Exposure: What You Can Do 

to Protect Yourself, available at http://www.epa.gov/radtown/sun-exposure.html#protect_ 

yourself.
28

endangerment is unsupported and suggests instead that it is EPA itself that is engaging in

presupposition. EPA should analyze the science, not make assumptions that arbitrarily truncate 

its analysis in order to reach preordained conclusions. 

2. Commingling GHG Effects and Non-GHG Effects

The Proposed Endangerment Finding includes statements that indicate that EPA is 

relying on effects of climate change in general. For instance, EPA says “the analysis was not 

restricted to only those climate and public health or welfare effects which may be attributable 

solely to greenhouse gas emissions from section 202(a) sources under the Act.” Id. at 18894/2. 

In addition to examining sources of GHG emissions that cannot be regulated under section 

202(a), the Administrator states:

There are other greenhouse gases and aerosols that have warming (and cooling) 

effects but are not being included in the proposed definition of air pollution. 

These include water vapor, chlorofluorocarbons (CFCs), 

hydrochlorofluorocarbons (HCFCs), halons, tropospheric ozone (O3), black 

carbon, and other short-lived precursor gases. For each of these substances, there 

are different scientific and policy reasons why these substances are not being 

included in the proposed definition of air pollution for purposes of section 202(a). 

Id. at 18896/3-18897/1.

The effects of these various causes of radiative forcing are not relevant to the question of

whether the six GHGs EPA addressed in the Proposed Endangerment Finding endanger public 

health or welfare. Nevertheless, although EPA notes that the “water vapor feedback mechanism 

in response to human-induced warming [is included] in all modeling scenarios of future climate 

change,” it fails to explain the extent to which these other causes of radiative forcing are 

included in the modeling results on which EPA relies. Id. at 18897/1, 18898/1.

Examination of the TSD reveals that EPA improperly commingles the effects on climate 

of the six GHGs for which it proposes to find endangerment with the effects of all other sources 

of climate change, both anthropogenic and biogenic. Accordingly, the TSD’s analysis is wholly 
29

unsuitable for the task of assessing endangerment for the group of GHGs that is the subject of 

this action. The Administrator’s proposed judgments based on the TSD are, therefore, inherently 

inaccurate. 

This fundamental flaw in the TSD is illustrated by many of the document’s specific 

descriptions of its purpose and content. For instance, EPA states that the TSD is intended to 

serve as an assessment of the 

extent to which observed climate change can be attributed to anthropogenic GHG 

emissions. . . . The term “climate change” in this document generally refers to 

climate change induced by human activities, including activities that emit GHGs.

Future projections of climate change, based primarily on future scenarios of 

anthropogenic GHG emissions, are shown for the global and national scale.

TSD at 1 (emphases added). 

As this quotation demonstrates, at the outset of its endangerment analysis, EPA 

simultaneously claims that it is assessing climate change associated with anthropogenic GHG 

emissions and that it is also addressing, in an unspecified manner, climate change that is not 

related to anthropogenic GHG emissions (or to GHG emissions of any sort). Further, as the 

Proposed Endangerment Finding does, the TSD describes the climate-related effects of changes 

in tropospheric ozone, anthropogenic emissions of aerosols, increases in stratospheric and 

tropospheric water vapor, changes in land cover, and changes in solar irradiance -- none of which 

are related to GHG emissions.

12 Id. at 20-22. 

Addressing the impacts that may result from climate change in general is not a proper

purpose of the TSD, and information on these impacts fails to support an endangerment finding. 

The proper purpose of the document is to assess whether anthropogenic emissions of the six 

12 Indeed, the Proposed Endangerment Finding makes clear that it is not seeking to regulate other 

sources of radiative forcing apart from the six GHGs. 74 Fed. Reg. at 18896/3-18898/1.
30

GHGs themselves contribute to an endangerment of public health or welfare. The TSD’s failure 

to limit the scope of its assessment to the effects of anthropogenic emissions of the six GHGs 

makes it impossible to determine from that document whether the effects described, and any 

asserted endangerment, result from anthropogenic emissions of the six GHGs or some 

combination of those emissions and other possible causes (e.g., anthropogenic emissions of other 

substances, biogenic emissions of GHGs or other substances, non-anthropogenic processes of 

various kinds such as natural climate variability, and human activities that do not involve 

emissions, such as land-cover practices). This hopelessly confounded analysis therefore cannot 

serve as a basis for an endangerment finding. Consequently, if it is to proceed further in this 

rulemaking, EPA must revise this document to address only those effects that are relevant to the 

proposed endangerment finding.

B. The TSD and the Proposed Endangerment Finding Rely on Sources of 

Scientific Information that Do Not Adequately Address the Issues Relevant 

Under the CAA.

The TSD and the Proposed Endangerment Finding rely on a number of sources of 

scientific information as the basis for their analysis and proposed conclusions regarding asserted 

public health and welfare endangerment from GHG-related climate change. Careful review of 

both the TSD and the Proposed Endangerment Finding indicates that EPA has relied almost 

exclusively on the IPCC’s Fourth Assessment Report and the Synthesis and Assessment Products 

prepared by the CCSP. See id. at ES-1 (“The conclusions here and the information throughout 

this document are primarily drawn from the assessment reports of the Intergovernmental Panel 

on Climate Change and the U.S. Climate Change Science Program.”). Nearly wholesale reliance 

on the IPCC and CCSP assessments is not consistent with EPA’s duties under the law or with 

sound scientific practice. EPA must conduct its own assessment of the science and cannot avoid 

this obligation for the sake of convenience.
31

Reliance on the IPCC is particularly problematic, as UARG explains in its comments on 

the Draft TSD released in conjunction with EPA’s ANPR. In those comments, UARG explains

that the IPCC Fourth Assessment Report does not contain the specific assessment of U.S. effects 

that would be required to support an endangerment finding. Instead, the IPCC Assessments are 

devoted primarily to global effects and global emissions. Further, UARG’s ANPR comments

argue that EPA’s adoption of the IPCC’s regional analysis of North American effects, including

projections of changes in temperature, precipitation, and sea level rise, is improper; analysis of 

such effects cannot substitute for a U.S.-specific analysis, particularly in light of the fact that the 

IPCC analysis and EPA’s discussion of that analysis fail to distinguish adequately between U.S. 

and Canadian effects. None of these shortcomings have been remedied, and EPA’s altered

rationale for continuing to rely on the IPCC analysis is as insufficient as its original rationale.

On the one hand, EPA has removed a reference to the opinions of two IPCC authors who 

stated that the “major conclusions” of the North American chapter “all apply to the United 

States” and that the topics and impacts discussed are “relevant to at least some locations in the 

United States.” Draft TSD, Doc. ID EPA-HQ-OAR-2008-0318-0082 at 63 (June 21, 2008)

(emphasis added). Removal of this attempted justification is appropriate because those opinions

were in no way dispositive, the exact meaning of the referenced statements was unclear, and 

reliance on the opinions of two individuals was inconsistent with the principles governing the 

IPCC’s work. 

Yet EPA now argues that the results of the North American assessment apply to the 

United States because “the IPCC North American chapter (of the Working Group II volume) on 

impacts, adaptation and vulnerability covers the U.S. and Canada (not Mexico) and . . . the 

general findings in that chapter (drawn from many individual studies for the U.S.) are indeed 
32

applicable to U.S. conditions.” 74 Fed. Reg. at 18894/2. Certain statements within the North 

American chapter may indeed apply to the United States; it would be remarkable if the IPCC had 

wholly ignored the United States. EPA fails, however, to address the critical issue, which is 

adequate delineation between U.S. and non-U.S. impacts, even though the Agency acknowledges 

that “the IPCC Working Group II report . . . may not provide as much regional detail within the 

U.S. as did the 2000 report, Climate Change Impacts on the United States: The Potential 

Consequences of Climate Variability and Change (NAST, 2000).” TSD at 5. 

The problems with reliance on the IPCC, however, extend beyond issues of the level of 

geographic detail. For instance, in describing the effects of climate change on -- in a section of 

the TSD titled “U.S. Precipitation” -- EPA cites the IPCC as the basis for its conclusions 

regarding changes to precipitation levels in Canada. Id. at 59; see also id. at 60 (discussing sea 

level rise in Canada under the heading “U.S. Sea Level Rise”). In the same section, and despite 

the Administrator’s assurances to the contrary, the TSD describes decreases in precipitation that 

may occur in Mexico. Id. at 59 (“more than 90% of the models project[] drying in northern and 

particularly western Mexico”). It should be obvious that Canadian and Mexican impacts are not 

U.S. impacts and do not belong in sections of the TSD that purport to address the effects of 

climate change in the United States. Moreover, this sort of confusion raises substantial questions 

about all of the TSD’s analyses. When EPA cites effects in “western North America,” based on 

IPCC analysis, to which nation is the Agency referring? Indeed, given that the Agency blatantly 

describes non-U.S. impacts in sections that are ostensibly intended to address the U.S., there is 

no reason to assume that EPA has not made similar, though perhaps more subtle, errors 

elsewhere. In short, the IPCC by and large does not provide U.S.-specific information, and EPA 
33

has not successfully extrapolated such information from the IPCC material. Reliance on the 

IPCC’s conclusions, therefore, is misplaced.

In addition, the IPCC Assessment Reports are not prepared in accordance with U.S. 

standards for scientific assessments. The IPCC is governed by its own official “Principles 

Governing IPCC Work,” available at http://www.ipcc.ch/pdf/ipcc-principles/ipcc-principles.pdf. 

These Principles emphasize that approval of the contents of IPCC Assessment Reports is 

obtained on the basis of consensus among IPCC member governments. Id. at 2. EPA’s TSD is 

subject not only to the CAA’s principles but also to the Data Quality Act (“DQA”), as discussed 

further in section VI of these comments, and to guidelines establishing standards for the quality,

objectivity, integrity, and utility of information disseminated by federal agencies. Pub. L. No. 

106-554, § 515; 67 Fed. Reg. 8452 (Feb. 22, 2002). Adopting scientific conclusions of a body 

not subject to these United States statutory requirements and principles -- and “generalizing” 

such conclusions to make them stand for propositions they were not designed to support --

undercut EPA’s claim that it has complied with the DQA’s requirements. Indeed, EPA itself 

highlights this issue when it describes the process for approving IPCC Assessment Reports and 

the DQA procedures used during review and approval of U.S. CCSP Synthesis and Assessment 

Products. See TSD at 3. Accordingly, EPA cannot continue to rely in this proceeding on the 

IPCC information and conclusions in the absence of an independent assessment by the Agency 

and establishment and application of transparent procedures to ensure compliance with U.S. 

standards.

There are additional reasons why EPA’s heavy reliance on IPCC documents, as well as 

CCSP reports, is improper. As EPA acknowledges, “scientific research is very active in many 

areas addressed in [the TSD] (e.g. aerosol effects on climate, climate feedbacks such as water 
34

vapor, and internal and external climate forcing mechanisms) as well as for some emerging 

issues (e.g. ocean acidification, and climate change effects on water quality).” Id. at 6-7. The 

Agency acknowledges that it received numerous comments on the draft TSD registering concern 

that the IPCC Fourth Assessment Report was “not current enough.” 74 Fed. Reg. at 18894/2. 

EPA has attempted to rectify this problem by including references to additional CCSP reports 

published since release of the draft TSD. Id. EPA thus acknowledges the importance of 

including the most recent scientific studies available. Unaccountably, however, EPA in most 

instances still fails to incorporate the results of important, peer-reviewed studies, studies of the 

same sort and caliber as those assessed by the IPCC and CCSP.13 The Agency cannot escape its 

obligation to review the current state of the science by suggesting that IPCC and CCSP reports 

are more valid than an independent Agency review would be, based on the broad assertion that 

those bodies have “assessed numerous individual studies in order to draw general conclusions 

about the state of science.” TSD at 5. Moreover, it is hardly dispositive that the IPCC and CCSP 

findings may be characterized as relatively “recent,” that they “have been reviewed and formally 

accepted by, commissioned by, or in some cases authored by, U.S. government agencies and 

individual government scientists,” or that “in many cases, they reflect and convey the consensus 

conclusions of expert authors.” Id. On an issue to which it ascribes such importance, EPA 

surely is capable of undertaking an analysis of its own that will address the current science in a 

responsible way. 

13 Likewise, EPA’s assertion that “[e]ven with more recent information available, the IPCC 

Fourth Assessment Report remains a standard reference, essentially serving as the benchmark 

against which new findings over the next few years will be compared,” is not a valid reason for 

EPA to continue to fail -- or refuse -- to make such comparisons in this proceeding. 74 Fed. Reg. 

at 18894/2.
35

Indeed, it is remarkable that, despite having had before it for months numerous comments 

on the ANPR alerting it to the need for independent Agency analysis to support any 

endangerment finding it may seek to make, EPA has flatly refused to conduct such an analysis. 

EPA’s position that it need not bother here, on such a momentous issue, with any independent 

scientific analysis -- the sort of scientific analysis EPA traditionally, and routinely, undertakes 

under the CAA when, for example, it reviews NAAQS -- is astonishing and plainly indefensible. 

It can be explained only by an Agency view that EPA “knows what the answer is” and need not 

investigate the facts. That is not an acceptable way for the Agency to discharge its 

responsibilities under the Act. 

That the IPCC and CCSP reports were prepared under conditions and for reasons 

substantially different from those related to an assessment of possible endangerment to U.S. 

public health and welfare in contemplation of regulation under the CAA reinforces the 

conclusion that EPA’s wholesale reliance on these reports is improper. As EPA notes, the 

IPCC has established rules and procedures for producing its assessment reports.

Report outlines are agreed to by government representatives in consultation with 

the IPCC bureau. Lead authors are nominated by governments and are selected 

by the respective IPCC Working Groups on the basis of their scientific credentials 

and with due consideration for broad geographic representation. . . . Drafts 

prepared by the authors are subject to two rounds of review; the second round 

includes government review. For the IPCC Working Group I report, over 30,000 

written comments were submitted by over 650 individual experts, governments 

and international organizations. . . . Each Summary for Policymakers is 

approved line-by-line, and the underlying chapters are then accepted, by 

government delegations in formal plenary sessions.

Id. at 3 (emphases added).

Thus, the IPCC Assessment development process is marked by pervasive

intergovernmental negotiations, including negotiations between the United States and other 

governments and among many non-U.S. governments, and by the influence of various forces that 
36

would have no sway in an independent analysis conducted by a U.S. government agency. In 

other words, as illustrated by EPA’s own description, in the TSD, of IPCC processes, IPCC 

products are at least as much a product of international diplomacy as they are of scientific 

inquiry. 

With regard to the CCSP Synthesis and Assessment Products, EPA notes that “[d]ifferent 

agencies have been designated the lead for different [synthesis and assessment products 

(“SAPs”)]; EPA is the designated lead for three of the six SAPs addressing impacts and 

adaptation.” Id. Accordingly, very few of the CCSP products have been developed consistent 

with EPA’s policies governing the preparation of influential scientific analyses or with the 

Agency’s particular expertise brought fully to bear.

Further, the development of these products is governed by the U.S. Global Change 

Research Act of 1990 (“GCRA”), which establishes standards for the preparation of scientific 

assessments that are wholly divorced from EPA’s obligations under the CAA. 15 U.S.C. §§ 

2921-2961. The primary purpose of the GCRA is the establishment and coordination of a 

national Global Change Research Program implemented by numerous federal agencies and 

overseen by the National Science and Technology Council, a cabinet-level entity chaired by the 

President and his Science Advisor. Id. §§ 2932, 2933; Executive Order 12881. The CCSP 

Reports were prepared to satisfy the requirements of section 106 of the GCRA, which calls for 

an integrative evaluation of the federal government’s Global Change Research Program. 15 

U.S.C. § 2936. This assessment is then used in the evaluation and refinement of the overall 

research program as new research areas are identified and funding priorities are established. Id.

§§ 2934, 2935. EPA’s analysis of endangerment under the CAA is wholly unrelated to 
37

evaluation and coordination of federal research programs and should be properly focused on the 

state of climate-related scientific understanding, whether publicly or privately conducted.

Indeed, EPA tacitly acknowledges the flaws in its approach when it discusses its chosen 

method of assessing the science related to ozone. Specifically, EPA states that it has “just 

recently completed and published an assessment of the literature on the effect of climate change 

on air quality (EPA, 2009). Therefore, because EPA evaluated the literature itself in the 

preparation of that assessment, EPA does cite some individual studies it reviewed in its summary 

of this topic in Section 8.” TSD at 6. Thus, with respect to ozone, EPA has itself evaluated the 

relevant studies, not simply adopted the conclusions of others.14 This approach allows the 

Agency to incorporate the most recent science and to decide for itself what is and is not relevant 

to an endangerment analysis. Moreover, although UARG does not necessarily agree with EPA’s 

statements on the ozone issue, the Agency’s discussion of that issue shows that it is capable of 

discharging its analytical responsibilities under the Act rather than outsourcing the job to other 

domestic and international entities that do not operate under, and are not bound by, the standards

of the CAA and U.S. administrative law.

In sum, the analysis and conclusions of the IPCC, as contained in its Fourth Assessment 

Report, are the primary basis for many of EPA’s proposed conclusions, including its most 

important determinations as to purported climate change-related effects in the United States. 

This is an inappropriate use of this information. Most of the IPCC conclusions concern global

14 In many cases, EPA simply reports IPCC and CCSP conclusions with respect to projected 

effects and the likelihood of the effects’ occurrence. See, e.g., 74 Fed. Reg. at 18888/2 & n.2 

(indicating that the IPCC believes the heating effects caused by GHGs are the likely cause of 

most observed global warming and that the IPCC believes this conclusion is characterized by 90 

to 99 percent confidence levels). As discussed above, EPA is obligated to provide its own 

judgments on these matters.
38

effects and emissions, information that, as used by EPA here, clouds the state of scientific 

knowledge with respect to whether GHG emissions from new U.S. motor vehicles will endanger

U.S. public health or welfare. Further, adoption of the IPCC’s North America conclusions as 

generally applicable to the United States is not scientifically justifiable. It is unclear precisely 

which effects cited in the TSD are relevant to the United States, and EPA’s failure to provide any 

additional analysis of this issue renders its conclusions unreliable. Further, the reports of both 

the IPCC and the CCSP fail to analyze the most recent relevant science and convey biases and 

irrelevant information that skew an assessment of the endangerment issue under the CAA. EPA 

may not proceed in this rulemaking on the basis of borrowed analyses that do not reflect the 

Administrator’s independent exercise of her statutory responsibilities. 

C. Conclusions in the Proposed Endangerment Finding Are Unclear and Must 

Be Revised. 

The Proposed Endangerment Finding contains a number of statements whose meanings 

are unclear. Given the importance of the issues addressed in this proposal, it is necessary that 

conclusions reached by the Administrator be clearly stated, precise, and accurate. This section of 

these comments identifies a number of statements in the Proposed Endangerment Finding that 

require greater explanation.

The Administrator states that the “atmospheric concentrations of greenhouse gases 

endanger public health and welfare within the meaning of Section 202(a) of the Clean Air Act.

She proposes to make this finding specifically with respect to six greenhouse gases that together

constitute the root of the climate change problem. . . .” 74 Fed. Reg. at 18886/1. Precisely what 

EPA means by the “root” cause requires explanation; EPA gives none. As the Administrator 

notes elsewhere, several factors other than anthropogenic emissions of the six EPA-targeted 

GHGs are believed to be sources of radiative forcing and climate change, and recent science 
39

indicates that some of these other factors may play a substantial role indeed.

15 Similarly, the 

Proposed Endangerment Finding states that “most of the observed global and continental 

warming can be attributed to this anthropogenic rise in greenhouse gases.” Id. at 18898/2 

(emphasis added). EPA cannot support an endangerment finding with such vague assertions. 

Some greater degree of scientific precision is required.

Elsewhere in the Proposed Endangerment Finding, the Administrator states that “[i]t is 

[her] judgment that the total body of scientific evidence compellingly supports a positive 

endangerment finding for both public health and welfare.” Id. at 18888/1. The Administrator 

adds that she “reached this judgment by considering both observed and projected future effects, 

and by considering the full range of risks and impacts to public health and welfare occurring 

within the U.S., which by itself warrants this judgment.” Id. Although this may, in fact, be the 

Administrator’s judgment, the Proposed Endangerment Finding must set out in significantly 

more detail which of the various effects the Administrator views to be adverse, which she 

believes are beneficial, and which may be neutral or characterized by such significant 

uncertainties as to frustrate development of an informed judgment as to their adversity or 

beneficence. Further, she must explain her specific assessment of the risks associated with each 

effect on which she bases any finding of endangerment. Instead, EPA states evasively that 

“[b]eneficial effects can coexist with harmful effects, and it is not necessary to reach a firm 

15 A recent study, for instance, demonstrates that global climate models consistently 

underestimate the percentage of climate forcing that is attributable to black carbon, a non-GHG. 

Further, this study found that a number of impacts associated with black carbon, including 

reduction of sea ice and snow albedo, dwarf similar effects that had been attributed to CO2. 

Ramanthan and Carmichael, Global and Regional Climate Changes Due to Black Carbon, 1 

NATURE GEOSCIENCE 221-27 (Apr. 2008).
40

conclusion, for particular domains and sectors, about the net result in order to reach an overall 

conclusion in favor of endangerment.” Id. at 18903/1.

Similarly, EPA states that it “believes . . . that serious risks and potential impacts to 

public health and welfare have been clearly identified, even if they cannot always be quantified 

with confidence.”16 Id. at 18904/1. EPA may believe these things, but the Proposed 

Endangerment Finding fails to demonstrate that any of them is true. Indeed, EPA notes that

when exercising her judgment the Administrator balances the likelihood and 

severity of effects. This balance involves a sliding scale; on one end the severity 

of the effects may be significant, but the likelihood low, while on the other end 

the severity may be less significant, but the likelihood high. Under either 

scenario, the Administrator is permitted to find endangerment.

Id. at 18890/2. There is, however, no indication in the Proposed Endangerment Finding 

that EPA has conducted this sort of balancing and assessment of severity and likelihood. 

The Proposed Endangerment Finding should explain EPA’s conclusions as to each of 

these factors for every climate-related effect that EPA evaluates. The current approach 

taken is insufficiently transparent and fails to provide an adequate scientific basis for the 

Proposed Endangerment Finding.

The Administrator’s further descriptions of various effects similarly fail to fulfill the 

obligation to explain clearly the Agency’s rationale for an endangerment finding. In many cases, 

the Administrator simply quotes findings of other entities, such as the IPCC, articulating nothing 

about her own judgments as to the accuracy of the descriptions, or the projections of the 

16 EPA also states that the Proposed Endangerment Finding “is based on weighing the scientific 

evidence, considering the uncertainties, and balancing any benefits to human health, society and 

the environment that may also occur.” 74 Fed. Reg. at 18904/1. The Proposed Endangerment 

Finding does not, however, demonstrate or describe EPA’s attempt to weigh evidence, consider 

uncertainties, or balance positive and negative impacts. All relevant details of any such 

assessment and rationale are completely missing.
41

probability, of the climate change-related effects that others have identified. See, e.g., id. at 

18888/2, 18896/2-3; see also id. at 18899/1-2 (providing a similar description of CCSP 

conclusions without providing any indication as to EPA’s assessment of these conclusions). For 

instance, in discussing international effects, EPA does nothing more than recite IPCC 

conclusions. Id. at 18903/2. Myriad questions remain unanswered: Does the Administrator 

agree with these assessments? Has she examined the basis for the IPCC’s conclusions? Has she 

examined relevant new science? Or are these statements simply information that the 

Administrator has considered but not fully adopted as accurate? These sorts of statements need 

to be placed in context. Likewise, EPA states:

Warming of the climate system is now unequivocal, as is 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 0.74°C (1.3°F) over the last 100 years. 

Eight of the ten warmest years on record have occurred since 2001.

Id. at 18896/2. This statement, as with the one noted above, simply raises additional questions. 

Does the Administrator view these changes as wholly negative? Has EPA evaluated positive 

effects of such changes? Until greater explanation is given for these types of assertions and 

conclusions, the overall import of these statements is unclear.

In sum, the Proposed Endangerment Finding does not adequately explain the basis for the 

Administrator’s proposed conclusion that anthropogenic emissions of six GHGs cause or 

contribute to air pollution that endangers the public health and welfare. For example, specific 

effects are not clearly identified by EPA as either positive or negative (or neutral). EPA also 

does not clearly express its determinations on many issues, instead uncritically quoting or citing 

conclusions of others. Thus, the Proposed Endangerment Finding does not provide a sufficient 

basis for proceeding to a final finding of endangerment under section 202(a) of the CAA.
42

D. Scientific Conclusions Stated in the TSD and Relied on by the Administrator 

Are Incorrect. 

The TSD fails to take into account a number of recent scientific studies that present

serious challenges to many of the specific conclusions stated in the document and that undermine 

certain key assumptions adopted in the IPCC and CCSP reports on which EPA relies.

Accordingly, conclusions stated by EPA in the Proposed Endangerment Finding do not rest on a 

sound foundation. 

The following section describes material from IPCC and CCSP reports on which EPA 

has chosen to rely, argues that additional sources should be assessed and included, and highlights 

major recent findings of significance to any endangerment analysis. 

The TSD itself has an elaborate and complicated system of organization. It begins by 

discussing GHG emissions and atmospheric concentrations. It then describes observed climate 

change effects, such as temperature changes, precipitation changes, sea level changes, ocean 

acidification, changes in physical and biological systems, and extreme event impacts. The TSD 

then addresses attribution of observed climate change to anthropogenic GHG emissions. Next, it

addresses projected GHG concentrations and future climate change effects, including emissions 

scenarios, changes in temperature, precipitation, sea level rise, ocean acidity, snow and ice, 

extreme events, and air pollution. Finally, the TSD assesses the impact that these various effects 

are projected to have on public health and welfare interests, including human health, air quality,

food production and agriculture, forestry, water resources, sea level and coastal areas, energy, 

infrastructure, settlements, and ecosystems and wildlife, as well as international impacts. The 

Administrator’s assessment in the Proposed Endangerment Finding is less detailed and addresses 

only certain of these issues.
43

The comments on the following pages reflect the TSD’s basic structure and address the 

scientific infirmities that afflict that document’s sections in order, adding references to the 

Proposed Endangerment Finding where relevant. It should be noted at the outset, however, that 

certain of the flaws identified in one section of the TSD are relevant to conclusions presented 

elsewhere in the document. Deficiencies in the TSD’s assessment of climate models or in its 

analysis of temperature trends, for instance, undermine all of the TSD’s stated conclusions 

derived from those models’ projections of future temperatures. Similarly, inaccuracies in 

descriptions of effects such as sea level rise or extreme events influence the TSD’s and the 

Proposed Endangerment Finding’s conclusions with respect to nearly all of the health and 

welfare impact assessments. These overarching issues are noted throughout these comments.

Additional problems result from the TSD’s structure. In particular, the document 

discusses the science addressing attempted attribution of potentially climate-related impacts to 

GHG emissions separately from its assessment of the severity and potential adversity of those

impacts. In effect, this results in an assessment of health and welfare impacts that ignores 

uncertainties and conflicting evidence by relegating all such discussion to earlier chapters that do 

not themselves address issues (such as severity, adversity, or beneficial effects) that may be 

ultimately determinative of the endangerment question. The Agency’s approach produces a 

misleading and inaccurate set of conclusions on questions of fundamental significance to the 

Agency’s endangerment inquiry. A result is overstatement of the certainty that various projected 

effects will occur.

1. GHG Emissions

The TSD describes both current and projected U.S. and global anthropogenic GHG

emissions. The accuracy of this information is critical because it forms the basis for linking 

specific effects of climate change to current and future GHG concentrations. Inaccuracies will 
44

distort assessment of risks. In almost every case, inaccuracies and flaws in EPA’s assessment of 

the science in this area lead to overstatement of risks. Correcting these inaccuracies is crucial, as 

it is clear that EPA has based the proposed endangerment and cause or contribute findings on this 

information. See 74 Fed. Reg. at 18886/1-3 (stating that emissions levels of six GHGs are part of 

the basis for the proposed endangerment and cause or contribute findings).

First, the TSD relies on EPA’s annual Inventory of U.S. Greenhouse Gas Emissions and 

Sinks (“U.S. Inventory”) for information regarding the primary GHGs of interest and indicates 

that this information is used to project effects of climate change. TSD at 1. As UARG notes in 

its comments on the draft TSD, the U.S. Inventory does not account for emissions and sinks 

resulting from land use changes and the forestry sector. This is important given the significance 

of U.S. land use changes and the TSD’s statement that, in the United States, the forestry sector is 

“a significant net sink, while in some developing countries it is a significant net source of 

emissions.” Id. at 10. EPA describes the nature of U.S. sinks excluded from the inventory as 

follows:

Removals of carbon through land use, land-use change and forestry activities are 

not included in Figure 2.2, but are significant; net sequestration is estimated to be 

883.7 TgCO2eq in 2006, offsetting 12.5% of total emissions (EPA, 2008).

Id.

As noted in the above-quoted language, however, the TSD does not include this 

information in the primary Figure stating the purported level of U.S. GHG emissions. Likewise, 

it ignores these important sinks in various other descriptions of U.S. emission levels. See, e.g., 

id. at 12 (“Excluding land use, land-use change, and forestry, U.S. emissions were 19% of the 

total year 2005 global emissions.”). While the TSD notes in passing the nature and significance 

of U.S. sinks, it fails to incorporate this information properly in all relevant sections of the TSD, 
45

including the key Figures, which EPA can be expected to use in its decisionmaking. Exclusion 

of this information results in a bias toward a finding that U.S. emissions contribute to

endangerment. This problem is exacerbated by the fact that EPA’s global emissions estimates 

may indeed include other countries’ forestry-related emissions and sinks, thereby skewing the 

Agency’s assessment of the relative importance of U.S. emissions. The significant deficiencies 

in EPA’s analysis include its failure to clarify what sources and sinks, both in the U.S. and 

internationally, are taken into account in its endangerment assessment and, in particular, its 

failure to represent fully and accurately U.S. carbon sinks.

Similarly, the TSD does not accurately reflect the state of scientific knowledge of

emissions of specific GHGs. For instance, regarding hydrofluorocarbons (“HFCs”), 

perfluorocarbons (“PFCs”), and sulfur hexafluoride (“SF6”), the TSD states: 

Concentrations of many of these gases have increased by large factors (between 

1.3 and 4.3) between 1998 and 2005. Their total radiative forcing in 2005 was 

+0.017 [±0.002] Wm-2and is rapidly increasing by roughly 10% per year. These 

gases are almost entirely anthropogenic in origin (Forster et al., 2007).

Industrial fluorinated gases . . . have relatively low atmospheric concentrations.

Concentrations of many of these gases have increased by large factors (between 

1.3 and 4.3) between 1998 and 2005. 

Id. at 15. The TSD cites the IPCC for these conclusions but misrepresents the conclusions 

reached in the Fourth Assessment Report. The IPCC states that these fluorinated gases come 

from “anthropogenic and natural sources.” IPCC Working Group I, Ch II at 145, Forster, P. et 

al., 2007 (emphasis added). Perhaps more significant, the above-quoted passage in the TSD 

implies that emissions of these gases are “rapidly increasing,” even though the IPCC Working 

Group I report on which EPA relies says that emissions of some of them have decreased or 

remained at relatively constant levels over the past 10 to 20 years. TSD at 15, see also id. at ES1; IPCC Working Group I, Ch. II at 145, Forster, P. et al., 2007 (describing decreases in 
46

fluorinated gases). Further, as the IPCC notes, concentration levels of some PFCs have not been 

updated “since 1997.” IPCC Working Group I, Ch II at 145, Forster, P. et al., 2007. EPA cannot 

overlook these important discrepancies. An endangerment determination must be based on a 

thorough assessment of all relevant facts, not on an oversimplified summary of the relevant 

information. Information on decreasing or stabilized emission levels in particular may warrant 

against a finding of endangerment and should be prominently reported, not hidden or muddled in 

confusing and internally contradictory statements.

Similar misrepresentations exist with respect to the TSD’s discussion of methane 

concentrations. The TSD states, for instance, that the global atmospheric concentration of 

methane (“CH4”) has “increased by 149% since pre-industrial levels (through 2007).” TSD at 

ES-1. Elsewhere, the TSD notes that global CH4 growth rates “declined between the early 1990s 

and mid-2000s” and further notes that concentrations grew between 2006 and 2007, “the first 

year-to-year increase since 1998.” Id. at 14. These conclusions are based primarily on the 

findings of the IPCC, which states that since the 1990s the emissions growth rate for CH4 has 

been “close to zero” and “below zero in 2001, 2004, and 2005,” the most recent years for which 

the IPCC examined emissions and concentration data. IPCC Working Group I, Ch II at 140, 

143, Forster, P. et al., 2007. As the IPCC notes, the result of these reductions is that what EPA 

believes is the second largest source of GHG radiative forcing (at least among the six GHGs 

targeted by the proposed EPA finding) has been significantly reduced. EPA fails to incorporate 

this significant information in any meaningful way in its analysis or to explain its relevance. 

EPA does note that the reasons for the single recent year of increase “are not yet known” and 

admits that the overall “decrease in the atmospheric CH4 growth rate and the implications for 

future changes in its atmospheric burden are not well-understood.” TSD at 14. EPA does not, 
47

however, explain how these uncertainties or the general trend toward lower CH4 atmospheric 

concentrations affect its analysis of endangerment. The TSD cannot provide a basis for an 

endangerment finding without an adequate explanation of this matter. 

The TSD also fails to address CO2 emissions adequately. It notes in passing that there is 

“year-to-year variability” in the annual CO2 concentration growth rate and that the growth rate is 

characterized by uncertainty estimated at 0.11 ppm/yr. Id. at 13 & n.9. The Agency fails to 

describe the implications of this variability and the related uncertainty. Does this have, for 

instance, any effect on attributing current observations to CO2 emission levels? Does it have any 

relevance to projecting future CO2 concentrations? EPA must explain the import of these facts 

and how they relate to its endangerment analysis. In addition, the TSD inaccurately reports that 

“[t]he present atmospheric concentration of CO2 exceeds by far the natural range over the last 

650,000 years (180 to 300 ppm) as determined from ice cores (Jansen et al., 2007).” Id. at 13. It 

cites Chapter 2 of the IPCC’s Working Group I Report for this conclusion. This information, 

however, does not appear in that chapter, and any basis that may exist for this statement is 

unclear.17

Further, the TSD misleadingly describes certain CO2-related effects that, while 

theoretically possible, are in no way likely to occur under any projected emissions scenario. 

Specifically, the document states that “[c]arbon dioxide concentrations above 5% may be 

dangerous for vegetation and as concentrations approach 20%, CO2 becomes phytotoxic. Carbon 

17 A similarly inaccurate citation to the IPCC appears on page 14 of the TSD with respect to 

methane concentrations. Further, the TSD states that “[i]ce core data show that the present 

atmospheric concentration of N2O is higher than ever measured in the ice core record of the past 

650,000 years (Jansen et al., 2007).” TSD at 15. This information does not appear in the IPCC 

Assessment that the TSD cites as its source. Indeed, the cited chapter of the IPCC report 

indicates that ice core data for N2O cover only 2,000 years. See IPCC Working Group I, Ch II at 

143, Forster, P. et al., 2007.
48

dioxide can cause death of plants through ‘root anoxia’, together with low oxygen concentration 

(IPCC, 2005).” Id. at 17. The Agency fails to mention, however, that these concentrations and 

these particular effects have been observed in, and are relevant to, only those areas that are 

exposed to massively high CO2 concentrations, such as those that result from large volcanic 

eruptions. Indeed, the IPCC report cited in the TSD for this proposition addresses the risk of this 

particular type of harm in the context of hypothetical massive CO2 releases. IPCC, Special

Report on Carbon Dioxide Capture and Storage at 248 (2005). The TSD instead implies that 

such effects could somehow result from atmospheric concentrations and other anthropogenic 

emissions in a manner that is plainly inconsistent with the information contained in the cited

source for this statement. TSD at 17. The TSD’s misrepresentation on this issue is not only

troubling but ironic, given that increased CO2 concentrations that may occur at more modest

levels in the atmosphere generally are very likely to have positive effects on plant growth and 

health, as described below in these comments.

In addition, in discussing projected future emissions scenarios, the TSD states that “[a]ll 

future GHG emission scenarios described in this section assume no new explicit GHG mitigation 

policies -- neither in the U.S. nor in other countries -- beyond those which were already enacted 

at the time the scenarios were developed.” Id. at 45. With regard to the scenarios developed by 

the CCSP and presented in the TSD, EPA further notes that “[t]he CCSP scenarios, because they 

were developed more recently than the IPCC SRES [Special Report on Emissions Scenarios] 

scenarios, do account for the implementation of the Kyoto Protocol for participating countries, 

but no explicit GHG mitigation policies beyond the Kyoto Protocol.” Id. at 47. Elsewhere, the 

TSD states that “mitigation measures to reduce GHGs, which could also reduce long-term risks, 

are not addressed. The purpose of this document is to review the effects of climate change and 
49

not to assess any speculative policy or societal response to climate change.” Id. at 2. Further, “it 

is the Administrator’s position that the purpose of the endangerment analysis is to assess the 

risks posed to public health and welfare, rather than to estimate how various . . . greenhouse gas 

mitigation policies may ameliorate or exacerbate any endangerment that exists.” 74 Fed. Reg. at

18894/3. Even assuming for the sake of argument that it is appropriate to exclude “speculative”

mitigation measures from EPA’s assessment of endangerment, it is indefensible to exclude 

existing and virtually certain mitigation measures from that assessment. Emission reductions 

that are planned or expected in foreign nations and at the federal, regional, state, and local levels 

in the United States should not be excluded from EPA’s projections simply because they are not 

in all cases guaranteed. Indeed, nothing addressed in the TSD is absolutely certain to occur; the 

Agency should attempt to base its projections on what is most likely to occur, not on arbitrary 

rules designed to evade difficult questions. EPA is willing to speculate as to large GHG 

emission increases; purposeful exclusion of likely mitigation measures is arbitrary and reflects a 

significant lack of balance in EPA’s analytical approach.

Finally, EPA notes in passing that there are considerable uncertainties associated with 

future GHG emissions projections. TSD at 48 (“The broad ranges of EMF-21 emissions 

projections in Figure 6.3, especially for N2O and the F-gases, illustrate the uncertainties in 

projecting these future emissions, which is generally consistent with the range found in SRES.”). 

Further, the TSD states:

Scenarios are story lines regarding possible futures. These storylines are designed 

to be internally consistent in their assumptions regarding population and 

economic growth, implementation of policies, technology change and adoption, 

and other factors that will influence emissions. Scenarios are not projections of 

the future, but are used to illustrate how the future might look if a given set of 

events occurred and policies [are] implemented.

Id. at 45 (emphases added).
50

Because these scenarios are “not projections of the future,” EPA does not assign 

probabilities to specific outcomes. On the one hand, because of the significant uncertainties 

inherent in such an endeavor, it is perhaps understandable that EPA would avoid undertaking this 

task. On the other hand, however, the Agency fails to address or resolve the fundamental 

problems that its approach creates. The bulk of the TSD describes possible effects associated 

with these projected scenarios, thereby implying that these effects will in fact occur in the future. 

Further, the Administrator proposes to base her endangerment and cause or contribute findings 

on these projected effects. 74 Fed. Reg. at 18898/2 (“Based on the total weight of evidence, ... it 

is the Administrator’s judgment that current and projected levels of the mix of the six 

greenhouse gases endanger the public health and welfare of current and future generations. The 

Administrator’s proposed endangerment finding is based on the entire range of observed risks 

and potential harms to public health and welfare.”) (emphases added). The scientific basis for 

reaching endangerment and cause or contribute findings is not adequately established due to the 

serious limitations on the Agency’s assessment of the substantial uncertainties associated with 

these issues. EPA would have to describe the relative probabilities of various future emissions 

projections before it could determine that the projected effects of those emissions endanger 

public health or welfare.

2. Observed and Projected Effects of GHG Concentrations

a. Temperature Trends and Modeling 

The science addressing temperature trends and their historical record has overarching and 

significant implications, similar to those related to projections of future GHG concentrations, for 

all of the various health and welfare impacts that EPA assesses in the TSD and Proposed 

Endangerment Finding. First, with regard to observed temperature trends, providing accurate 
51

information can guard against unfounded attribution of various phenomena to climate change. 

The TSD, however, does not assess adequately current temperature trends and often engages in 

broad generalizations while failing to explain the import of various conclusions and facts that are 

presented. 

For instance, the Proposed Endangerment Finding states:

2005–2007 were exceptionally warm years (among the top 10 warmest on 

record), while 2008 was slightly warmer than average (the 39th warmest year on 

record), 0.2 °F (0.1 °C) above the 20th century (1901–2000) mean.

The last ten 5-year periods (2004–2008, 2003–2007, 2002–2006, 2001–2005, 

2000–2004, 1999–2003, 1998–2002, 1997–2001, 1996–2000, and 1995–1999), 

were the warmest 5-year periods in the 114 years of national records, 

demonstrating the anomalous warmth of the last 15 years.

Id. at 18899/1; see also TSD at 27. Neither the Proposed Endangerment Finding nor the TSD, 

however, provides any insight into the significance of these facts. The TSD notes that 2008 was 

significantly cooler than recent preceding years but that it “tied with 2001 as the eighth warmest 

year on record for the Earth.” TSD at 24. The TSD also notes that “1998 and 2005 remain the 

two warmest years on record.” Id. Further, EPA reports without comment that the addition of 

data from 2006 through 2008 to temperature trend analysis performed by the IPCC alters trends 

“from + 0.11°C to + 0.15°C per decade compared to the estimate of + 0.12°C to + 0.19°C per 

decade given in IPCC (2007a).” Id. at 25. It may be arguable that year-to-year variation does 

not significantly alter overall trends and that the years selected and five-year bins that EPA has 

reported are in some way significantly revealing as to overall temperature trends. Yet EPA 

neither attempts to make such arguments nor to explain the significance and reliability of the 

data it includes in the TSD and the Proposed Endangerment Finding. Similarly, EPA offers no 

discussion of uncertainties related to the relevance of this information or a description of the role 

that inter-annual variability may play in assessing the robustness of any trends. Accurate 
52

representation of this information is crucial, especially given that, as EPA points out, a variety of 

short-term factors -- such as radiative forcing resulting from solar-modulated cosmic ray

ionization, surface albedo changes, water vapor, and black carbon -- are likely to play a 

significant role in temperature changes and do so over short timescales. Id. at 22. 

These same problems are also evident in EPA’s discussion of warming trends over 

various geographic regions. For instance, the TSD states:

Between 1901 and 2005, warming is statistically significant over most of the 

world’s surface with the exception of an area south of Greenland and three 

smaller regions over the southeastern U.S. and parts of Bolivia and the Congo 

basin. The lack of significant warming at about 20% of the locations, and the 

enhanced warming in other places, is likely to be a result of changes in 

atmospheric circulation.

Id. at 24; see also id. at 28 (“Regional data . . . indicate warming has occurred throughout most 

of the U.S., with all but three of the eleven climate regions showing an increase of more than 1oF 

since 1901 through 2006 (NOAA, 2007). . . . [T]he greatest temperature increase occurred in 

Alaska (3.3°F per century). The Southeast shows essentially no trend over the entire period, but 

has warmed since 1979.”) (emphasis added).

EPA states that 20 percent of the globe, including portions of the United States, has 

shown no statistically significant warming, but suggests that this anomaly is not compelling and 

should be ignored. But EPA does not assess the uncertainties in its hypothesis or discuss any 

evidence that may support or refute its conclusions. Likewise, EPA provides no discussion of

the basis for its conclusion that “statistically significant” warming has occurred or the relative 

confidence it has in that conclusion. 

Similar vagueness plagues EPA’s general comparisons of recent temperatures to 

temperatures in the past. EPA states, for instance, that “global mean surface temperature was 

higher during the last few decades of the 20th century than during any comparable period during 
53

the preceding four centuries.” Id. at 26. Yet the Agency also notes that “[l]arge-scale surface 

temperature reconstructions . . . yield a generally consistent picture of temperature trends during 

the preceding millennium, including relatively warm conditions centered around A.D. 1000 

(identified by some as the “Medieval Warm Period”) and a relatively cold period (or “Little Ice 

Age”) centered around 1700.” Id. The Medieval Warm Period, of course, falls outside the fourcentury period EPA selectively identifies as the baseline period for comparing historic 

temperatures to those in recent decades. This sort of general and imprecise discussion is not a 

sufficient basis on which to evaluate the endangerment question.

Another instance of selective and misleading timescale choice is found in EPA’s use of 

the year 1750 as the pre-industrial base point from which subsequent radiative forcing, i.e.,

warming or cooling effects, is measured. See, e.g., id. at ES-2, 19, 22, 31; 74 Fed. Reg. at 

18896/2. The IPCC, which the Agency cites for this information, indicates that in the period 

between the years 1600 and 1800, CO2 mixing ratios actually dropped by 5 to 10 ppm and that 

using 1750 as the pre-industrial index “may slightly overestimate the RF [radiative forcing], as 

the changes in the mixing ratios of CO2, CH4 and N2O after the end of this naturally cooler 

period may not be solely attributable to anthropogenic emissions.” IPCC Working Group I, Ch 

II at 140, Forster, P. et al., 2007. EPA fails to acknowledge this important caveat.

While relying on vaguely stated conclusions regarding observed temperature trends, the 

TSD further suffers from failure to evaluate thoroughly the implications of errors and flaws in 

the historical climate record. This information, for instance, is crucial for evaluating the 

reliability of climate change-related modeling results, which are compared to climate records to 

assess their ability to replicate accurately past climatic conditions. Moreover, the temperature 

record is used as an input in climate models and thus influences how those models perform and 
54

the projections they generate. A number of studies address flaws of this sort. EPA largely 

ignores them. Similarly, the TSD notes that “[s]urface temperature is calculated by processing 

data from thousands of world-wide observation sites on land and sea. Parts of the globe have no 

data, although data coverage has improved with time. The long-term mean temperatures are 

calculated by interpolating within areas with no measurements using the collected data 

available.” TSD at 22. This is significant information noting shortcomings in the available data. 

Yet, while the TSD notes that other issues may result in biases or inaccuracies (only to reject the 

biases and inaccuracies as inconsequential), it fails even to mention, let alone analyze, the 

possible distortions introduced by interpolation of temperature data. The TSD also does not

explain in any useful detail what parts of the globe continue to lack data, and it likewise presents 

no meaningful assessment of the nature of the data improvements that EPA believes have 

occurred. These yawning gaps in EPA’s analysis almost inevitably heighten uncertainty and 

introduce further bias to the endangerment assessment, but, again, EPA is silent on such matters.

Further, additional studies have uncovered significant flaws in the temperature record --

flaws EPA wholly ignores. Regarding ocean temperatures, one study recently uncovered 

previously undocumented biases that have resulted in significant overestimation of long-term

temperature changes in the global ocean. Gouretski and Koltermann, How Much is the Ocean 

Really Warming?, 34 GEOPHYSICAL RESEARCH LETTERS L01610 (2007). The significance of the 

ocean temperature record was recently reinforced by the investigations of Keenlyside et al.,

Advancing Decadal-Scale Climate Prediction in the North Atlantic Sector, 45 NATURE 84-88 

(May 2008), which found that use of more accurate sea surface temperatures resulted in global 

surface temperature projections that, over the next several decades, would fall within natural 

climate variability. Similarly, a number of recent studies have uncovered comparable flaws, 
55

uncertainties, and biases in the multi-decadal surface air temperature record. Thompson et al., A 

Large Discontinuity in the Mid-Twentieth Century in Observed Global-Mean Surface 

Temperature, 453 NATURE 646-49 (May 29, 2008); Pielke et al., Unresolved Issues With the 

Assessment of Multidecadal Global Land Surface Temperature Trends, 112 J. OF GEOPHYSICAL 

RESEARCH D24508 (Dec. 29, 2007); Pielke et al., Documentation of Uncertainties and Biases 

Associated with Surface Temperature Measurement Sites for Climate Change Assessment, 

AMERICAN METEOROLOGICAL SOCIETY 913-28 (June 2007); Lin et al., An Examination of 1997-

2007 Surface Layer Temperature Trends at Two Heights in Oklahoma, 34 GEOPHYSICAL 

RESEARCH LETTERS L24705 (Dec. 22, 2007). These findings require reanalysis of modeling 

results previously relied on by the IPCC and the other synthesis reports cited by EPA, as they are 

likely to have substantial effects on climate projections. Such reanalysis could, in turn,

fundamentally alter projections with respect to all other purported climate change-related

impacts. Findings of this sort demonstrate the need for EPA to perform its own comprehensive 

literature search and scientific assessment.

Other studies, unrelated to discrepancies and flaws in the temperature record, also

indicate that similarly pervasive inaccuracies may affect past climate modeling projections and 

that considerable reanalysis would be required before EPA could reasonably use those 

projections in this proceeding. For instance, Spencer, R.W., and W.D. Braswell, Potential 

Biases in Feedback Diagnosis from Observational Data: A Simple Model Demonstration, 21 J.

OF CLIMATE 5624-28 (Nov. 2008), determined that previous estimates of the sensitivity of the 

climate system based on satellite data were biased toward the high side due to the neglect of 

natural cloud variability. This study found that failure to account for natural, chaotic cloud 

variability, a problem that continues to plague climate modeling, will always project a climate 
56

system that appears more sensitive than it really is. Another recent study, Ramanthan and 

Carmichael, Global and Regional Climate Changes Due to Black Carbon, 1 NATURE 

GEOSCIENCE 221-27 (Apr. 2008), demonstrates that global climate models underestimate the 

percentage of climate forcing that is attributable to black carbon, a non-GHG. Accordingly, 

climate models that instead attribute this forcing to GHGs are necessarily inaccurate and their 

results require reassessment.

The TSD chooses to ignore these very real issues. It cites the IPCC for the conclusion 

that:

Biases may exist in surface temperatures due to changes in station exposure and 

instrumentation over land, or changes in measurement techniques by ships and 

buoys in the ocean. It is likely that these biases are largely random and therefore 

cancel out over large regions such as the globe or tropics (Wigley et al., 2006). 

Likewise, urban heat island effects are real but local, and have not biased the 

large-scale trends (Trenberth et al., 2007).

TSD at 22.

The findings of the studies described above, however, constitute direct challenges to 

IPCC conclusions and those that EPA cites as reasons for ignoring potential biases resulting from 

temperature-record flaws. It is inappropriate and internally inconsistent for EPA to continue to 

disregard the most current scientific findings on historical temperature records in favor of 

outdated IPCC conclusions even as the Agency updates IPCC conclusions with temperature data 

for the most recent years. The new information described above requires reconsideration of 

those modeling results that attributed various changes to GHG emissions where significant 

variables were ignored or where other factors may have been the primary causes of climate 

effects. These issues go directly to the asserted basis for the Proposed Endangerment Finding.

Finally, in addition to the problems that temperature data and similar issues pose for 

climate and climate impact projections, significant weaknesses are inherent in the design of the 
57

climate models used to generate the information presented in the TSD and relied on by EPA in 

the Proposed Endangerment Finding. EPA fails to address these issues, and misleadingly 

describes climate change models as “well-tested,” characterized by “a foundation in accepted 

physical principles,” and possessing the “ability to reproduce observed features of current 

climate and past climate changes.” Id. at 39. These assertions are overbroad and ignore critical 

shortcomings in modeling capabilities. As stated in a 2008 CCSP Report, current models contain 

“a number of systematic biases,” their strengths and weaknesses “vary substantially” from model

to model, and “several important aspects of the climate system present especially severe 

challenges to the goal of simulation.” CCSP, Climate Models: An Assessment of Strengths and 

Limitations at 1 (July 2008). This report goes on to characterize in significant detail a variety of 

uncertainties and problems presented by current models. The TSD addresses none of those 

uncertainties and problems. Moreover, in the few instances in which the TSD mentions model

inconsistencies or uncertainties, it explains them away as “under investigation” -- leaving their 

implications unaddressed, even while tacitly, if perhaps inadvertently, conceding that model 

results are not now in a state in which EPA could rely on them for a regulatory determination 

such as an endangerment finding. See, e.g., TSD at 41.

In sum, the TSD’s discussion of temperature trends is generally vague and simplistic and 

fails to grapple with the most pressing questions with anything like an adequate level of detail. 

Moreover, a number of recent studies raise serious questions about the reliability of the 

temperature record data used in the modeling studies on which EPA relies. The Agency ignores 

this information without providing any reason for its omission. Finally, the models themselves 

are known to suffer from a variety of weaknesses; these, too, are ignored by EPA, which persists 
58

in misrepresenting their reliability. Accordingly, the information EPA cites is inadequate to 

support the Proposed Endangerment Finding.

b. Precipitation

The TSD and the Proposed Endangerment Finding make a number of claims regarding 

the likely effects of climate change on precipitation globally and in the United States. Regarding 

observed precipitation trends, the Administrator concludes that “[o]ver the contiguous U.S., total 

annual precipitation increased at an average rate of 6.5 percent over the period 1901–2006.” 74 

Fed. Reg. at 18899/1. Further, EPA states that “[g]lobal mean precipitation is expected to 

increase with global warming.” Id. at 18900/1. The Agency also notes “substantial spatial and 

seasonal variations” in projected precipitation. Id. The TSD provides additional detail on 

expected precipitation effects. See, e.g., TSD at 29-30 (explaining U.S. regional increases in 

observed precipitation). The TSD also states that most of the United States will experience a 

“widespread increase in annual precipitation” except the southwest, which models indicate will 

experience drying. Id. at 59. 

Several problems undermine EPA’s presentation of the science related to precipitation 

effects of climate change. First, the TSD states in a number of sections that “[i]t is likely that 

there have been increases in the number of heavy precipitation events (e.g., 95th percentile) 

within many land regions, even in those where there has been a reduction in total precipitation 

amount, consistent with a warming climate and observed significant increasing amounts of water 

vapor in the atmosphere.” Id. at 29; see also id. at ES-2, 36. The TSD mischaracterizes this as 

an “observation” of current climate change impacts on precipitation events. This is a guess, not 

an observation. Elsewhere, EPA says that such increases have been reported, without specifying 

where or at what frequency, while casually noting that “only a few regions have sufficient data to 

assess such trends reliably (Trenberth et al., 2007).” Id. at 36. 
59

More broadly troubling is the lack of any significant description of the uncertainties 

associated with EPA’s projections in the TSD sections directly addressing precipitation. These 

problems are substantial and critical to a proper evaluation of whether endangerment will result 

from these projected climate change effects. The CCSP’s assessment of model strengths and 

weaknesses states clearly that projections of precipitation in some cases remain “problematic” 

(especially at the regional scale). See id. at 52-53. Likewise, the CCSP has concluded that 

“[t]here is no clear evidence to date of [an effect of] human-induced global climate change on 

North American precipitation amounts.” See id. at 43 (citing Clark et al., Abrupt Climate 

Change, Executive Summary 7-18, A Report of the U.S. Climate Change Science Program and 

the Subcommittee on Global Change Research 2008)); see also id. at ES-3 (“clearly attributing 

specific regional changes in climate to emissions of greenhouse gases from human activities is 

difficult, especially for precipitation”). This statement reflects the weaknesses of the relevant 

models. Yet the Administrator’s conclusions in the Proposed Endangerment Finding completely 

disregard these findings, and the TSD itself downplays them without justification. These 

problems must be addressed and their implications examined if EPA chooses to rely on this 

information. As EPA notes, “[c]hanges in precipitation patterns will play a large role in 

determining the net impacts of climate change at the national and sub-national scales, where 

uncertainties about precipitation changes remain very large.” Id. at 84 (emphasis added). It is 

plainly unacceptable for EPA to ignore these substantial uncertainties. 

c. Sea Level Rise and Sea Ice

The Proposed Endangerment Finding states that “[w]arming of the climate system is now 

unequivocal, as is evident from observations of ... rising global average sea level.” 74 Fed. Reg.

at 18896/2. Further, the Administrator concludes that “[t]here is strong evidence that global sea 

level gradually rose in the 20th century and is currently rising at an increased rate.” Id. at 
60

18898/3; see also TSD at 30. EPA then states additional and increasingly speculative 

conclusions. For instance, the Administrator cites IPCC conclusions that sea level will, by the 

end of this century, be between 0.18 and 0.59 meters higher than in 1990 and that rapid ice loss 

through various ice sheet flow processes could increase the rate of sea level rise. 74 Fed. Reg. at 

18900/2. Further, the Administrator concludes that “[w]hile understanding of these ice sheet 

processes is incomplete, their inclusion in models would likely lead to increased sea-level 

projections for the end of the 21st century.” Id. Regardless, the Administrator concludes that 

“the rate of change will increase in the future, exacerbating the impacts of progressive 

inundation, storm-surge flooding, and shoreline erosion.” Id. at 18902/3. These conclusions

closely mirror statements in the TSD.

These conclusions are not supported by the available science. Indeed, as EPA notes, sea 

level changes are due in significant part to factors other than GHG emissions and climate change, 

such as land subsidence. Id. at 18899/1. The TSD, on occasion, makes this concession as well, 

see, e.g., TSD at 60, although it regularly downplays the role of land subsidence, suggesting --

without showing -- that it does not have significant effects or that its role in sea level change 

should somehow be counted towards a finding of endangerment from GHG emissions. See, e.g., 

id. at 30 (“Two major processes lead to changes in global mean sea level on decadal and longer 

time scales: i) thermal expansion, and ii) the exchange of water between oceans and other 

reservoirs (glaciers and ice caps, ice sheets, and other land water reservoirs).”). Moreover, as the 

TSD acknowledges, “[v]ertical land motion from geologic processes may decrease (uplift) or 

increase (subsidence) the relative sea level rise at any site.” Id. at 60. Accordingly, reassessment 

of EPA’s conclusions on sea-level rise would be necessary before EPA could use them to 

support an endangerment finding.
61

There is also a considerable amount of science suggesting that the Administrator’s 

conclusions regarding the potential for sea level to rise at an increasing rate over time is 

incorrect. Indeed, the TSD itself notes that “[i]t is unclear whether the faster rate [of sea level 

rise] for 1993 to 2003 is a reflection of short-term variability or an increase in the longer-term

trend (Bindoff et al., 2007).” Id. at 30. Further, recent studies ignored by the TSD also 

contradict EPA’s assessment. One study indicates that ice sheets are less susceptible to climate 

change-related loss of mass than has previously been suggested. In particular, this study reported 

that ice sheets can adjust to what some assumed to be feedback mechanisms thought to cause 

accelerated melting, thus indicating that abrupt melting from increased ice flow is unlikely. See

Van de Wal et al., Large and Rapid Melt-Induced Velocity Changes in the Ablation Zone of the 

Greenland Ice Sheet, 321 SCIENCE 111-13 (July 4, 2008). An additional study indicates that

ocean temperatures have not risen in response to anthropogenic climate change and that any 

increase in ocean temperature is regional in nature and the result of natural variability. Lozier et 

al., The Spatial Pattern and Mechanisms of Heat-Content Change in the North Atlantic, 319 

SCIENCE 800-03 (Feb. 8, 2008). The TSD and the Proposed Endangerment Finding, however, 

omit any discussion of these recent studies and assert that ocean warming associated with climate 

change is unequivocal and that it is and will continue to contribute to sea level rise.

Similarly, the TSD and the Proposed Endangerment Finding rely on outdated projections 

of future sea level rise. The most recent study assessing sea level rise modeling results 

concludes that previous estimates, including those calculated by the IPCC, are roughly double 

currently supportable sea level rise expectations. Bamber, et al., Reassessment of the Potential 

Sea-Level Rise from a Collapse of the West Antarctic Ice Sheet, 324 SCIENCE 901-03 (May 
62

2009). Again, this raises substantial questions as to a number of the TSD’s assertions and 

requires reconsideration of the additional impacts EPA attributes to ice sheet loss. 

d. Ocean Acidification

The Proposed Endangerment Finding states that “[o]cean acidification is projected to 

continue, resulting in the reduced biological production of marine calcifiers, including corals.” 

74 Fed. Reg. at 18902/3. This conclusion is remarkable given the paucity of information in the 

TSD on this issue, which receives less than a page of analysis in that document. See TSD at 31, 

57. Indeed, the TSD characterizes ocean acidification as an “emerging issue[]” that investigators 

are only beginning to examine. Id. at 6. Despite its scant analysis, the TSD suggests future CO2

emissions will be absorbed by the oceans, “thereby reducing calcification rates of organisms who

[sic] rely on the minerals for development.” Id. at 57. The evidence adduced for these effects is 

meager, while the abundant uncertainties are wholly ignored. Further, for the reasons discussed

above, considerable uncertainties greatly limit EPA’s ability to rely on projections of future 

emissions scenarios, and EPA does not even attempt to assign probabilities to various potential 

outcomes. Accordingly, no legitimate basis exists for EPA’s assertions that ocean acidification 

will occur and result in the level of impacts it projects. 

e. Physical and Biological Systems

The TSD addresses the science examining whether climate change affects a variety of

ecosystem components. For example, regarding water resources, the TSD states that drought 

conditions are becoming more severe in some regions, increased runoff and streamflow are 

resulting from glacier melt and snowmelt, lakes and rivers are experiencing increased 

temperatures, and rivers are experiencing increased discharge. Id. at 33. The TSD 

acknowledges, however, that “[s]ome local trends in reduced groundwater and lake levels have 

been reported, but studies have been unable to separate the effects of variations in temperature 
63

and precipitation from the effects of human interventions such as groundwater management 

(Rosenzweig et al., 2007).” Id.

Regarding each of the ecosystem issues that the TSD discusses, EPA must provide 

significantly more detail for any reasonable analysis of endangerment to be possible. For 

instance, the TSD states that drought may occur in “other areas” or in “some regions” with “no 

clear trends for North America as a whole.” Id. at 28, 33, 37. Thus, it is unclear from the 

science assessed in the TSD where and how any drought-related effects may occur. Further, the 

TSD states that “most of the continental United States experienced reductions in drought severity 

and duration over the 20th century” and that drought in the western United States has been 

attributed to “multidecadal fluctuations.” Id. at 37. Accordingly, it appears that drought 

conditions can be attributed to causes other than climate change, contradicting the conclusions 

asserted in the TSD and the Proposed Endangerment Finding. Further, given that projections of 

drought are necessarily based on modeling of temperature increases and precipitation, which, as 

demonstrated above, are subject to significant reliability problems, EPA’s conclusions as to that 

asserted effect are especially questionable. Similarly, the TSD’s discussion of streamflow and 

runoff is abbreviated and provides no explanation of the evidence available, uncertainties 

associated with that evidence, or any significant regional detail. Finally, the TSD’s discussion of 

river discharge is, again, cursory at best. Moreover, the TSD entirely ignores scientific evidence 

demonstrating that, while climate-related changes in precipitation theoretically could affect river 

discharge, few rivers have experienced any significant changes in the current period, and any 

changes that might occur in the future are much more likely to be caused (or overwhelmed) by 

factors unrelated to climate change, such as damming and irrigation. Milliman et al., Climatic 

and Anthropogenic Factors Affecting River Discharge to the Global Ocean, 1951-2000, 62 
64

GLOBAL & PLANETARY CHANGE 187-94 (2008). It is impossible to base an endangerment 

finding on such a perfunctory, incomplete, and scientifically unsupported discussion. 

The TSD also states that biological systems are being affected by changing climate. It 

points to range shifts for flora and fauna, changes in biodiversity, changes in phenology and 

breeding, and hibernation patterns and attributes them to climate change. TSD at 34. The TSD

notes that changes observed in marine species are more difficult to attribute to climate change 

due to “other stresses (e.g. over fishing and pollution).” Id.

Regarding these effects, the TSD says that different species will have different capacities 

for adapting to changes (even as it refuses to analyze the effects of adaptation) and that such 

changes will result in “alter[ed] ecosystem structure, function, and services.” Id. at ES-6. The 

TSD also notes that evidence for local disappearance of species is “limited.” Id. at 34. Thus, 

EPA concedes that even local disappearances, which are not necessarily tied to extinctions or 

even to problems, are not well-supported. Suggesting that mass extinctions or severe ecological

consequences could result based on this evidence is completely unfounded. Thus, the TSD fails 

to provide any objective measure of the consistency or strength of the available scientific 

evidence for this particular type of asserted effect. Moreover, it provides little information that 

could serve as guidance to the Administrator in determining to what extent such an effect is

adverse or “endangering.” Indeed, although the Administrator cites this potential effect in the 

Proposed Endangerment Finding, she offers no explanation of how or whether these effects 

negatively impact public health or welfare. See 74 Fed. Reg. at 18903/1. In fact, new scientific 

evidence indicates climate change is much less likely than some observers previously thought to 

result in an influx of invasive species or in biodiversity losses. For instance, one recent scientific 

analysis determines that animal diseases previously thought to have been exacerbated by 
65

changing climatic conditions are in fact unrelated to climate. Lips et al., Riding the Wave: 

Reconciling the Roles of Disease and Climate Change in Amphibian Declines, 6 PLOS BIOLOGY

441-54 (Mar. 2008) (finding that amphibian declines due to disease increases are not related to 

climate change). 

Other recent evidence indicates that previously common assumptions regarding potential

species-level impacts of changing temperatures, and distribution of those impacts, suffer from 

serious inaccuracies. Particularly important is the recent finding that species impacts will likely 

be greatest in the tropics, largely outside of the United States, and that species in higher latitudes 

are far more resilient to climate change. Deutsch et al., Impacts of Climate Warming on 

Terrestrial Ectotherms Across Latitude, 105 PNAS no. 18 (May 6, 2008). Similarly, a study 

recently published in the Proceedings of the National Academy of Sciences concluded that the 

introduction of invasive plant species to new ecosystems does not necessarily result in significant 

species loss or harm, as is often argued. Sax and Gaines, Species Invasions and Extinction: The 

Future of Native Biodiversity on Islands, 105 PNAS 11490-97 (Aug. 12, 2008). Similarly, a 

2009 study concludes that climate change will in fact result in range contractions for five 

widespread and dominant invasive plant species, and that climate change will present an 

opportunity to restore native species in areas that today pose a considerable challenge for land 

managers. Bradley, et al., Climate Change and Plant Invasions: Restoration Opportunities 

Ahead?, GLOBAL CHANGE BIOLOGY (2009). The science presented in the TSD regarding this 

issue is accordingly an insufficient basis for an endangerment finding.

The TSD also discusses the effects of elevated CO2 levels on plant growth and species 

diversity. It notes that “[c]arbon dioxide can have stimulatory or fertilization effect[s] on plant 

growth.” TSD at 17. Indeed, it cites the IPCC conclusion that “at ambient CO2 concentrations 
66

of 550 ppm (approximately double the concentration from pre-industrial times) crop yields 

increase under unstressed conditions by 10-25% for C3 crops, and by 0-10% for C4 crops.” Id. 

Yet, without explaining its reasoning, EPA dismisses this potential benefit of GHG emissions as 

“small.” Id. Inconsistently, EPA uses no similar qualifiers for any remotely comparable 

percentage impact that might arguably point to adverse effects. See, e.g., id. at 62 (tropical 

storms), 77 (pollutant concentration episodes), 92 (forest fire risks), 92 (tree line movement), 94 

(streamflow change), 105 (cooling and heating changes).

Further, the TSD distorts the relevant science in this area by suggesting that ambient CO2

levels could result in “noticeable die-off” due to root anoxia, but fails to explain that this effect 

will not occur as a result of any projected CO2 concentration likely to occur and that it in fact has 

been observed only where CO2 makes up 20 to 95 percent of soil gas, such as is found in areas 

exposed to volcanic activity. Id. at 17. This information thus is irrelevant and misleading. 

Finally, the TSD tries to downplay the benefits associated with CO2 fertilization by 

suggesting it will reduce the quality of animal livestock forage, with more nutritious grasses 

being replaced by a less nutritious variety. This assertion is unfounded and, again, misleading. 

The TSD itself acknowledges that “the exact effects on both types of grasses and their nutritional

quality still need[] to be determined.” Id. at 87. The overt bias in EPA’s characterizations and 

its attempt to minimize benefits reflect an unacceptable approach to questions of scientific 

evidence underpinning any endangerment finding. 

f. Extreme Events

EPA cites several categories of extreme events and their purportedly increased potential 

as a basis for the Proposed Endangerment Finding. For instance, the Agency says that 

“[w]idespread changes in extreme temperatures have been observed in the last 50 years.” 74 

Fed. Reg. at 18898/3. EPA also quotes the CCSP’s conclusions:
67

Many extremes and their associated impacts are now changing. For example, in 

recent decades most of North America has been experiencing more unusually hot 

days and nights, fewer unusually cold days and nights, and fewer frost days.

Heavy downpours have become more frequent and intense. Droughts are 

becoming more severe in some regions, though there are no clear trends for North 

America as a whole. The power and frequency of Atlantic hurricanes have 

increased substantially in recent decades, though North American mainland landfalling hurricanes do not appear to have increased over the past century. Outside 

the tropics, storm tracks are shifting northward and the strongest storms are 

becoming even stronger.

Id. at 18899/2. At the same time, EPA notes that there are “key uncertainties” related to how 

“the frequency of hurricanes and other extreme weather events may change in a changing 

climate.” Id. at 18903/3.

The TSD further discusses the science related to observed and projected extreme events 

and their association, if any, with climate change and GHG emissions. The TSD states that 

“[c]old days, cold nights, and frost have become less frequent, while hot days, hot nights, and 

heat waves have become more frequent (IPCC, 2007d).” TSD at 36; see also id. at 61-62. Yet 

the TSD fails to provide any additional information on the significance of these changes or 

whether they might have overall positive or negative consequences. 

Moreover, the TSD states that “[i]t is likely that there have been increases in the number 

of heavy precipitation events” -- even though it acknowledges the absence of data to substantiate 

that claim. Id. at 36, 62. This bald speculation is not scientifically justifiable and has no place in 

a document intended to support a finding on the endangerment issue. 

Regarding drought, the TSD contradicts the conclusion stated by the Administrator. The 

TSD explains that “most of the continental United States experienced reductions in drought 

severity and duration over the 20th century. However, there is some indication of increased 

drought severity and duration in the western and southwestern United States.” Id. at 37

(emphasis added); see also id. at 62 (discussing drought under various emissions scenarios). 
68

Other statements in the TSD are equally at odds with the Administrator’s statement in the 

Proposed Endangerment Finding. See, e.g., id. at 64 (citing IPCC conclusion that “it is not clear 

if the present drying [in the United States] is outside the range of natural variability and linked to 

anthropogenic causes”). 

Similarly, regarding tropical cyclones and hurricanes, both of which the Administrator 

relies on in the Proposed Endangerment Finding, EPA candidly states that “there is no clear trend 

in the annual numbers of tropical cyclones” due to a “large suite of problems with the historical 

record of tropical cyclone activity.” Id. at 36, 62. Further, a recent study ignored by EPA 

indicates hurricanes are likely to be substantially rarer events under projected climate change. 

Knutson et al., Simulated Reduction in Atlantic Hurricane Frequency Under Twenty-FirstCentury Warming Conditions, 1 NATURE GEOSCIENCE, 359-64 (2008). 

Finally, the TSD states that extreme sea levels may increase. TSD at 36, 62. This briefly 

stated finding fails to elaborate on any of the relevant studies, discussed above, that undercut 

projections of increases in both the rate and amount of sea level increases, and it does not so 

much as mention any of the numerous uncertainties underlying these observations and 

projections. 

Thus, each of the extreme event categories described in the TSD and cited in the 

Proposed Endangerment Finding are reviewed by EPA in only the most superficial way. 

Moreover, the TSD itself contradicts the Administrator’s stated conclusions. In any event, a far 

more meaningful assessment of the underlying science would be required to determine whether 

this information could support an endangerment finding; EPA’s desire to reach a predetermined 

outcome does not allow it to avoid a thorough vetting of uncertainties and relevant new 

information. 
69

g. “Abrupt” Climate Change

The Proposed Endangerment Finding is vague with respect to precisely how “abrupt 

climate change” considerations factor into EPA’s proposed action. The Administrator does state, 

however, that “[i]f the harm [of a particular purported climate change-induced effect] would be 

catastrophic, the Administrator is permitted to find endangerment even if the likelihood is 

small.” 74 Fed. Reg. at 18890/2. Likewise, in discussing abrupt climate change specifically, the 

Administrator states:

Even if the probability of extremely high-impact events may be small, the 

existence of such high impact events, and the potential for other currently

unknown catastrophic impacts that could plausibly result from record-high 

atmospheric greenhouse gas levels, substantially bolsters the case for an 

endangerment finding with respect to greenhouse gases.

Id. at 18903/3.

The TSD’s discussion of the science evaluating abrupt climate change concedes that 

investigation of that matter is “in its infancy.” See, e.g., TSD at 57 (evidence for rapid variations 

in glacial outflow is based on models that are “in their infancy”). Indeed, EPA makes no

assessment of the possibility of abrupt climate change impacts on various health and welfare 

interests simply because, as it acknowledges, potential abrupt climate change implications 

“cannot be predicted with confidence, particularly for specific regions.” Id. at 63. The Agency’s 

complete failure to do anything other than note the possibility that abrupt climate change may

occur, and its decision to refrain from examining any impacts to public health and welfare, make 

the Administrator’s reference to “the existence of such high impact events” and her statement 

that such hypothesized “events” “substantially bolster[] the case for an endangerment finding,” 

74 Fed. Reg. at 18903/3 (emphasis added), completely implausible. As EPA has acknowledged, 

Congress barred EPA from basing its assessments and projections on a “crystal ball inquiry.” 73 
70

Fed. Reg. at 44422/3 (quoting legislative history of 1977 CAA amendments); see UARG ANPR 

Comments at 23.

The TSD suggests abrupt climate change might be triggered by any number of 

occurrences unrelated to GHG emissions. These include changes in Earth’s orbit, a brightening 

or dimming of the sun, and emissions of climate-altering particles. TSD at 63. Further, as the 

TSD notes, the fact that “[s]cientific data show that abrupt changes in the climate at the regional 

scale have occurred throughout history and are characteristic of the Earth’s climate system” 

illustrates the point that any abrupt climate change that may occur would not necessarily be the 

product of GHG emissions. Id.

In sum, this issue is riddled with uncertainties, as EPA acknowledges, and EPA’s 

discussion of it consists of little more than speculation. The Agency fails to assess the 

propensity of any abrupt climate change to impact public health and welfare interests, and it 

suggests that various factors unrelated to GHGs may be the likely cause of any abrupt change, 

should it occur. The discussion of this issue in the TSD and the Proposed Endangerment Finding 

simply does not provide a basis for an endangerment finding.

h. Ozone and Air Pollution

The Proposed Endangerment Finding concludes that “[i]ncreases in regional ozone 

pollution in the U.S. relative to ozone levels without climate change are expected due to higher 

temperatures and a modification of meteorological factors. Increases in regional ozone pollution 

increase the risks of respiratory infection, aggravation of asthma, and premature death.” 74 Fed. 

Reg. at 18901/2. Further, the Administrator concludes that climate change will exacerbate the 
71

“[s]ubstantial challenges [that] remain with respect to achieving the air quality protection 

promised by the NAAQS for ozone.”18 Id. at 18901/3.

The TSD supposedly provides the foundation for the Administrator’s conclusions. The 

TSD, however, is replete with inaccuracies and overstatements and does not in fact support the 

Administrator’s conclusions on this issue. For instance, it concludes that “[t]here is now 

consistent evidence from models and observations that 21st-century climate change will worsen 

summertime surface ozone in polluted regions of North America compared to a future with no 

climate change (Jacob and Winner, 2009).” TSD at 75. The TSD notes briefly that the relevant 

modeling studies “found some regions of the country where simulated increases in cloud cover, 

and hence decreases in the amount of sunlight reaching the surface, partially counteracted the 

effects of warming temperatures on ozone concentrations in these regions, to go along with the 

many regions where the effects of temperature and cloud cover reinforced each other in 

producing O3 increases.” Id. at 76. Similarly, it notes that climate change “can be expected to 

influence the concentration and distribution of air pollutants through a variety of direct and 

indirect processes, including the modification of biogenic emissions, the change of chemical 

reaction rates, wash-out of pollutants by precipitation, and modification of weather patterns that 

influence pollutant buildup.” Id. at 75. Again, some of the suggested effects are positive; some 

18 It is noteworthy that, in the Proposed Endangerment Finding, the Administrator does not cite 

any purported effects of climate change on particulate matter (“PM”) levels. The TSD makes 

clear, however, that the limited science that is available on that point suggests that “PM generally 

decreases as a result of simulated climate change, due to increased atmospheric humidity and 

increased precipitation.” TSD at 79 (emphasis added). It is therefore appropriate that EPA not 

rely on PM effects as a basis for proposing to find endangerment. On the other hand, if EPA 

were to proceed to a final endangerment finding, it would have to first address the potential 

health benefits from possible climate change-related PM reductions.
72

are negative. In addition, the TSD describes substantial uncertainties that attend the modeling of 

ozone-related impacts:

· “Relative to the other greenhouse gases, there is less confidence in reproducing the 

changes in ozone associated with large changes in emissions or climate, and in the 

simulation of observed long-term trends in ozone concentrations over the 20th century 

(Forster et al., 2007).” Id. at 15.

· “More frequent occurrences of stagnant air events in urban or industrial areas could 

enhance the intensity of air pollution events, although the importance of these effects is 

not yet well quantified (Denman et al., 2007).” Id. at 76.

These weakly stated acknowledgements that climate change will result in some ozone 

decreases and that specific posited effects are uncertain are still insufficiently reflective of the 

actual scientific record, which undermines EPA’s reliance here on any supposed increase in 

ozone. EPA’s own Assessment of the Impacts of Global Change on Regional U.S. Air Quality: A 

Preliminary Synthesis of Climate Change Impacts on Ground-Level Ozone, EPA/600/R-07/094F 

(April 2009) (“Ozone Assessment”), indicates that there are significant regions of the United 

States that are indeed likely to see ozone decreases associated with climate change; that 

reductions in ozone precursor emissions likely will overwhelm any increases that may result 

from climate change; and that, ultimately, the science in this area is riddled with uncertainties 

with respect to ozone (and PM). Moreover, EPA makes clear in its Ozone Assessment that 

scientific analysis of these issues and the development of models that might project climaterelated ozone changes are only now in the most preliminary of phases. Astonishingly, the TSD 

and the Proposed Endangerment Finding omit any reference to these facts, even though they

were publicly reported by the Agency itself in the very month in which it issued the Proposed 

Endangerment Finding. EPA’s approach here of ignoring or distorting scientific assessments, 

including even its own contemporaneous report, is arbitrary and indefensible.
73

3. Effects on Public Health and Welfare

As explained above, EPA’s assessment of climate change effects is divided into two 

primary sections, one addressing GHGs and their relation to climate change and phenomena that 

may be related to climate change (e.g., changes in temperature and precipitation, sea level rise, 

and extreme events), and another examining the impact these phenomena could have on various 

public health and welfare interests. This part of UARG’s comments focuses on EPA’s 

evaluation of climate change impacts on: (1) human health; (2) air quality; (3) food production 

and agriculture; (4) forestry; (5) water resources; (6) sea level rise and coastal areas; (7) energy, 

infrastructure, and settlements; (8) ecosystems and wildlife; and (9) international impacts. As 

described in section V.A.2, supra, numerous flaws undermine the analysis and underlying data 

relied on by EPA in the TSD and the Proposed Endangerment Finding with respect to direct 

effects of GHGs on climate changes. Similar problems also undermine the Agency’s 

conclusions with respect to the specific public health and welfare effects that may be related to 

those changes.

a. Human Health

Among the most clearly unsupported parts of the Proposed Endangerment Finding is that 

which addresses asserted effects on public health. EPA properly acknowledges that GHG 

emissions are not likely to have any direct effect on public health. 74 Fed. Reg. at 18902/1; TSD 

at 157 (“Greenhouse gases, at both current and projected atmospheric concentrations, are not 

expected to pose exposure risks on human respiratory systems (i.e., breathing/inhalation).”). 

EPA asserts, however, that “effects which may flow from a welfare effect,” i.e., indirect health 

effects that may result from climate change, should be treated as public health threats regardless 

of their welfare-based cause. 74 Fed. Reg. at 18902/1. While any episode of mortality or 

morbidity resulting from any proximate cause is by definition a health impact, EPA has failed to 
74

grasp the legal significance of this issue under the CAA. Indeed, the Agency fails even to note 

the fact that CAA regulation to protect against exclusively indirect health impacts is 

unprecedented. Further, the Agency does not even attempt to answer whether Congress intended 

that EPA regulate emissions under the CAA based on indirect health impacts of what otherwise 

constitute welfare effects. There are, for instance, statements in the legislative history of the 

CAA indicating that only direct health effects fall within the regulatory authority granted in the 

Act. See, e.g., H.R. Rep. No. 95-294 at 51 (1977) (“[T]he Committee intends to require the 

Administrator to consider all sources of the contaminant which contribute to air pollution and to 

consider all sources of exposure to the contaminant -- food, water, air, etc. -- in determining 

health risks.”); S. Rep. No. 91-1196 at 7 (1970) (“The protection of the public health and welfare 

requires definitive knowledge of the causal relationships between exposure to air pollution 

agents -- singly or in combinations -- and health or welfare under varying environmental 

conditions.”) (emphasis added). The Agency cannot avoid these fundamental legal questions. It 

must address them directly.

Perhaps even more important, EPA fails even to begin to address one of the most 

fundamental problems with its fatally deficient proposal: The Administrator’s acknowledged 

inability to make any conclusion as to whether the current or projected climate change 

phenomena that EPA describes has (or will have), on balance, a negative or a positive effect on 

human mortality and morbidity. As the Administrator observes:

[W]arming temperatures may bring about some health benefits. Both extremely 

cold days and extremely hot days are dangerous to human health. But at least in 

the short run, modest temperature increases may produce health benefits in the 

U.S. (and elsewhere). Although the IPCC projects reduced human mortality from 

cold exposure through 2100, it is currently difficult to ascertain the balance 

between increased heat-related mortality and decreased cold-related mortality. 

With respect to health, different regions will be affected in different ways. The 
75

Administrator does not believe that it is now possible to quantify the various 

[human health] effects [including effects on human mortality].

74 Fed. Reg. at 18901/2 (emphases added). Thus:

· EPA acknowledges that extremely cold weather -- which would be reduced under the 

projections of climate change on which EPA relies -- results in increased human 

mortality;

· The IPCC, which EPA treats as authoritative, “projects reduced human mortality from 

cold exposure” due to projected climate change over at least the next nine decades, until

at least the end of this century (a period EPA apparently views as “the short run”); and

· The Administrator has concluded that, at least at the present time, it is “not . . . possible”

to determine whether projected climate change will, on balance, result in more or less 

human mortality.

In addition, EPA’s assessment of the science, in its TSD, states forthrightly that “[i]t is not clear 

whether reduced mortality from cold will be greater or less than increased heat-related mortality 

in the U.S. due to climate change (Gamble et al., 2008).” TSD at 70. Thus, EPA concludes, 

“additional research is needed” to understand the mortality question. Id. at 71.

Nevertheless, in the face of this profound scientific uncertainty on this most important of

public health or welfare effects, the Administrator concludes that it is “reasonable” to determine

that public health is endangered. 74 Fed. Reg. at 18901/2. EPA cites no precedent, and UARG 

is aware of none, for this extraordinary result. Cf. Massachusetts v. EPA, 549 U.S. 497, 534

(2007) (“If the scientific uncertainty is so profound that it precludes EPA from making a 

reasoned judgment as to whether” the endangerment criterion is met, “EPA must say so.”). EPA 

is utterly silent on its rationale for proposing to find endangerment notwithstanding what it 

characterizes as unresolvable uncertainty as to which way the balance of human mortality (and 

morbidity) may fall. EPA likewise fails to address the corollary fundamental question of how, in 

light of the admitted possibility that net weather-related human mortality would decline under 
76

projected climate change, the Agency could find endangerment of non-human-health “welfare” 

interests and, on that basis, regulate emissions it believes contribute to that climate change.

Moreover, EPA’s specific statements regarding asserted human health impacts of climate 

change are unjustified or inadequately supported. EPA states, for instance, that, based on the 

IPCC Fourth Assessment Report, “risks to public health will be more severe in 20 years than in 

ten years, more severe in 30 years than in 20 years, more severe in 40 years than in 30 years, and 

so forth,” even while acknowledging that “[t]here is disagreement about whether and when 

increases in adverse effects will be linear or nonlinear.” 74 Fed. Reg. at 18901/1. Regardless of

this uncertainty, however, the Administrator “believe[s] that existing evidence supports a finding 

that there are current adverse effects. This evidence also supports a finding that these effects will 

become more serious over the next several decades, in some cases out to 2100.” Id.; see also id. 

at 18901/2 (“The Administrator simply means to recognize, with the scientific community, that 

concentrations of greenhouse gases endanger public health through a wide range of pathways.”).

In addition to these general conclusions, the Administrator makes special note of several 

potential pathways for human health effects to result from climate change. Addressing the 

relationship between temperatures and human mortality and morbidity, EPA states that 

“unusually hot days and nights and heat waves have become more frequent in the U.S. [and] are 

projected to intensify . . . with likely increases in mortality and morbidity.” Id. Yet, as noted 

above, the Administrator “acknowledges that warming temperatures may bring about some 

health benefits” and that “at least in the short run, modest temperature increases may produce 

health benefits in the U.S. (and elsewhere).” Id. Despite this and the fact that the Administrator 

cannot “quantify the various effects,” she concludes that “[b]ecause the risks from unusually hot 

days and nights, and from heat waves, are very serious, it is reasonable to find on balance that 
77

these risks support a finding that public health is endangered even if it is also possible that 

modest temperature increases will have some beneficial health effects.” Id.

EPA’s rationale for this proposed conclusion that heat-related effects on human health 

suffice to support an endangerment finding is inconsistent with the available science. Indeed, the 

Agency’s reasoning in the Proposed Endangerment Finding is undermined by statements in its 

own TSD. For example, as noted above, the TSD states that “[i]t is not clear whether reduced 

mortality from cold will be greater or less than increased heat-related mortality in the U.S. due to 

climate change (Gamble et al., 2008).” Moreover, the TSD explains that “[h]eat exposures vary 

widely, and current studies do not quantify the years of life lost due to high temperatures. 

Estimates of heat-related mortality attributable to climate change are reduced but not eliminated 

when assumptions about acclimatization and adaptation are included in models.” TSD at 70. 

The TSD adds that “additional research is needed”:

[M]ortality patterns in U.S. cities are relatively insensitive to temperature 

variability. . . . Given the paucity of recent literature on the subject and the 

challenges in estimating and projecting weather-related mortality, IPCC 

concludes additional research is needed to understand how the balance of heatand cold-related deaths might change globally under different climate scenarios 

(Confalonieri et al, 2007).

Id. at 71. Indeed, the uncertainty surrounding this issue is heightened in light of the significant 

questions related to modeling and temperature trends in particular, as noted in other sections of 

these comments, that also undermine EPA’s conclusions.

Further, the Agency’s selective citation to, and discussion of, the various effects that have 

examined this issue reveal significant biases that distort the presentation of the available 

evidence. First, EPA has removed from the TSD, without explanation or justification, reference 

to “several studies that indicate decreases in winter mortality may be greater than increases in 

summer mortality in some temperate counties under climate change,” despite including this 
78

information in an earlier draft. Compare Draft TSD, Doc. ID EPA-HQ-OAR-2008-0318-0082 at 

66 (June 21, 2008) with TSD at 71. Moreover, despite a direct request from the Office of 

Management and Budget in a document summarizing the results of an interagency review 

proceeding,19 EPA has refused to incorporate an assessment of a 2007 study by Deschenes and 

Moretti that demonstrates that extremely cold days are more dangerous to human health than 

extremely hot days. It appears that EPA has determined that it will not address the science that 

would tend to demonstrate a net health benefit related to mortality and temperature changes, 

even though such an analysis is crucial to answering questions that are central to a proper 

endangerment analysis.

The Administrator also points to health effects that may stem from a climate changerelated “increase in the spread of several food and water-borne pathogens (e.g., Salmonella, 

Vibrio) among susceptible populations.” 74 Fed. Reg. at 18901/3. She states that the “primary 

climate-related factors that affect these pathogens include temperature, precipitation, extreme 

weather events, and shifts in their ecological regimes.” Id. If the TSD’s contents are any 

indication, however, EPA has invested few resources in analyzing the effects of these climaterelated factors on disease pathogens. Although it reports IPCC conclusions that disease may 

become more prevalent, see, e.g., TSD at 69, 71, it provides no analysis of uncertainties and

probabilities or any quantitative assessment of likely impacts-- even while observing that disease 

and health impacts related to drought are “likely to be experienced in developing countries and 

not directly in the U.S.,” further weighing against any endangerment determination based on 

health factors. Id. at 72. 

19 Office of Management and Budget, Summary of Interagency Review Proceedings Document, 

EPA-HQ-2009-1071-01241 at 3.
79

In addition, the Administrator asserts that:

Climate change, including the direct changes in carbon dioxide concentrations 

themselves, could impact the production, distribution, dispersion and allergenicity 

of aeroallergens and the growth and distribution of weeds, grasses and trees that 

produce them. These changes in aeroallergens and subsequent human exposures 

could affect the prevalence and severity of allergy symptoms.

74 Fed. Reg. at 18901/3. At the same time, however, the Administrator acknowledges that “the 

scientific literature does not provide definitive data or conclusions on how climate change might 

impact aeroallergens and subsequently the prevalence of allergenic illnesses in the U.S.” Id.

Interestingly, while mentioning this potential effect, the Administrator avoids saying that it is a 

basis for the Proposed Endangerment Finding -- and for good reason. The TSD notes the lack of 

scientific evidence linking increases in aeroallergens to human health impacts. TSD at 74. In 

fact, this type of uncertainty is comparable to the uncertainty that characterizes the other human 

health effects that the Administrator relies on for the Proposed Endangerment Finding.

Therefore, just as it is inappropriate to rely on speculative climate-related effects on 

aeroallergens, insufficient scientific information exists to justify a finding that GHG emissions 

endanger public health.

Finally, it is important to emphasize that the TSD includes numerous, more general 

statements that raise further doubts as to the adequacy of a basis for concluding that public health 

will be adversely affected by climate change. For instance, the TSD states that “[h]uman system 

responses to climate change are more difficult to identify and isolate due to the larger role that 

non-climate factors play (e.g., management practices in agriculture and forestry, and adaptation 

responses to protect human health against adverse climatic conditions) (Rosenzweig et al., 

2007).” Id. at 44 (emphasis added). EPA fails even to attempt to address these complications in 

the TSD or in the Proposed Endangerment Finding.
80

b. Ozone and Air Quality

Regarding the air quality effects of climate change and their potential to impact public 

health and welfare, the Administrator concludes:

Increases in regional ozone pollution in the U.S. relative to ozone levels without 

climate change are expected due to higher temperatures and a modification of 

meteorological factors. Increases in regional ozone pollution increase the risks of 

respiratory infection, aggravation of asthma, and premature death. EPA does 

have in place National Ambient Air Quality Standards (NAAQS) for ozone, 

which are premised on the harmfulness of ozone to public health and welfare.

These standards and their accompanying regulatory regime have helped to reduce 

the dangers from ozone in the U.S. Substantial challenges remain with respect to 

achieving the air quality protection promised by the NAAQS for ozone. These 

challenges will be exacerbated by climate change. 

74 Fed. Reg. at 18901/2-3 (emphases added). 

Thus, according to the Administrator, ozone levels will be higher than might otherwise be 

the case if no climate change were to occur. Moreover, this might require additional efforts of 

some unspecified sort to maintain compliance with existing CAA regulatory standards that are 

requisite to protect public health and welfare. Although the Administrator’s proposed findings 

touch on issues related to endangerment under the CAA, they demonstrate that the standard for 

making a positive determination has not been satisfied. Indeed, the Administrator does not claim 

that climate change will result in an inability to comply with existing regulations that protect 

public health and welfare from ozone pollution, only that continued protection might require 

increased efforts. EPA has not shown that this is a basis for an endangerment finding.

Finally, as noted above, EPA’s TSD statements contradict the Agency findings reached 

two months ago in its Ozone Assessment. The TSD summarizes that report’s findings repeatedly 

in a misleading and incomplete manner. EPA cannot rationally proceed to an endangerment 

finding on the basis of a TSD that is inconsistent with its own contemporaneous report.
81

c. Food Production and Agriculture

EPA states a number of proposed conclusions related to asserted impacts of climate 

change on food production and agriculture. It notes, for instance, that “[c]limate changes are 

very likely already affecting U.S. water resources, agriculture, land resources, and biodiversity as 

a result of climate variability and change.” Id. at 18899/1. The Agency notes that there will be 

aggregate benefits for agriculture in the early decades of this century with increased yields of 

approximately 5 to 20 percent, even while asserting that “as temperature rises, these crops will 

increasingly begin to experience failure, especially if climate variability increases and 

precipitation lessens or becomes more variable.” Id. at 18902/2-3. EPA also proposes to 

conclude that “[h]igher temperatures will very likely reduce livestock production during the 

summer season, but these losses will very likely be partially offset by warmer temperatures 

during the winter season.” Id. at 18902/3. Despite the benefits concededly associated with

climate change for this sector, the Administrator states that ultimately the existence of these 

benefits “is not inconsistent with a judgment that greenhouse gases in the atmosphere endanger 

welfare. Beneficial effects can coexist with harmful effects, and it is not necessary to reach a 

firm conclusion, for particular domains and sectors, about the net result in order to reach an 

overall conclusion in favor of endangerment.” Id. at 18903/1.

Given these statements, it is not entirely clear whether EPA is proposing to determine 

that effects on food production and agriculture support or do not support its purported basis for 

finding endangerment. It is possible to read the Administrator’s findings as indicating that she 

believes the positive effects will ultimately be outweighed by the negative effects; on the other 

hand, her statements may be interpreted to mean that the overall beneficial effects of climate 

change for this sector are outweighed by negative effects on other health and welfare interests.

The Administrator’s conclusions do not appear to be consistent with the conclusions of the U.S. 
82

Department of Agriculture, as expressed in a recent CCSP report, The Effects of Climate Change 

on Agriculture, Land Resources, Water Resources, and Biodiversity in the United States, SAP 

4.3 (May 2008). In that report, the Department of Agriculture concludes that most crops for 

which there are data will experience net productivity gains, despite certain projected negative 

impacts resulting from temperature increases, precipitation changes, and increased pest and 

disease activity. Id. at 59, 70-71.

The Agency must provide clarity on these issues. In an opinion later modified and then 

reversed on other grounds, the U.S. Court of Appeals for the D.C. Circuit held that the CAA 

requires EPA to consider both adverse and beneficent health effects of pollutants and to assess 

“net” health impacts. American Trucking Ass’ns, Inc. v. EPA, 175 F.3d 1027, 1053 (D.C. Cir. 

1999). As in the American Trucking case, EPA must determine likely net health impacts before 

it can reasonably conclude that GHG emissions pose a risk to public health. Yet, this is precisely 

what EPA has failed to do in the Proposed Endangerment Finding.

Regardless of EPA’s analysis, the evidence presented by EPA regarding these issues 

indicates substantial beneficial effects that should not be downplayed or disregarded, as the 

Agency appears to be doing. Further, it bears repeating that many of the Agency’s conclusions 

related to the negative impacts that climate change might have on this sector require revision 

after a reassessment of the science addressing the direct effects of GHG emissions on climate 

change factors, such as precipitation, drought, extreme events, and temperature projections. 

Further, the section of the TSD addressing these issues appears to exhibit significant bias. 

It fails even to attempt to quantify the relative impacts of positive and negative effects except in 

those instances where the Agency can find an argument that minimizes benefits. See, e.g., TSD 

at 84 (discussing and downplaying positive benefits of direct CO2 exposure); id. at 85-86
83

(suggesting that extreme events may offset any benefits of moderate climate change). This bias 

calls into question the remainder of this section’s analysis. 

Similarly, speculation in this section of the TSD undermines its reliability. Specifically, 

the TSD asserts that elevated CO2 levels can reduce livestock feed’s nutritional value by leading 

to a decrease in C4 grasses and an increase in C3 grasses. It also states, however, that “the exact 

effects on both types of grasses and their nutritional quality still need[] to be determined.” Id. at 

87. EPA thus contradicts its own prediction of negative effects by its acknowledgement that the 

matter remains undetermined.

Furthermore, the TSD states in general, outside of the section addressing these impacts, 

that “[h]uman system responses to climate change are more difficult to identify and isolate due to 

the larger role that non-climate factors play (e.g., management practices in agriculture and 

forestry, and adaptation responses to protect human health against adverse climatic conditions) 

(Rosenzweig et al., 2007).” Id. at 44 (emphasis added). The TSD fails, however, to address 

these difficult uncertainties in its actual analysis of agricultural effects. Indeed, it is unclear 

whether any of these considerations factored into EPA’s assessment of this area of the science. 

Accordingly, the Proposed Endangerment Finding and the TSD fail to present a persuasive case 

in support of endangerment based on agriculture and food production impacts. 

d. Forestry

The Administrator’s ultimate position on whether forestry impacts support or do not 

support her proposed endangerment finding is unclear. 74 Fed. Reg. 18903/1 (“The 

Administrator acknowledges that as for human health, so too for welfare: moderate temperature 

increases may have some benefits, particularly for . . . forestry over the short term. . . . This 

possibility is not inconsistent with a judgment that greenhouse gases in the atmosphere endanger 

welfare. Beneficial effects can coexist with harmful effects, and it is not necessary to reach a 
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firm conclusion, for particular domains and sectors, about the net result in order to reach an 

overall conclusion in favor of endangerment.”). The Administrator reports that both negative 

and positive effects on forestry are expected:

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. . . . IPCC reported that overall forest growth 

for North America as a whole will likely increase modestly (10–20 percent) as a 

result of extended growing seasons and elevated CO2 over the next century, but 

with important spatial and temporal variation. 

Id. at 18902/2-3. The Administrator also cites tropospheric ozone increases as negatively 

impacting forest growth. Id. The conclusions contained in the TSD by and large mirror the 

Administrator’s proposed findings, discussing such issues as increased forest growth, increased 

wildfires and drought, more frequent insect and disease outbreaks, more severe extreme event 

disruptions, and reduced biodiversity resulting from the spread of invasive species.

Again, EPA’s projections are subject to serious question due to the Agency’s failure to

reassess previous modeling results in light of new scientific studies, as discussed above. Further, 

projections of invasive species impacts should be reexamined in light of recent studies, discussed 

further in section V.D.2.e above, indicating that climate change will have considerably less of an 

impact in this regard. See Sax and Gaines; Bradley et al.

It is also important to note that the Administrator’s discussion of this issue ignores 

several other climate change-related sources of forest growth benefits. The TSD states: 

Forest productivity gains may result through: (i) the direct stimulatory CO2

fertilization effect (although the magnitude of this effect remains uncertain over 

the long term and can be curtailed by other changing factors); (ii) warming in cold 

climates, given concomitant precipitation increases to compensate for possibly 

increasing water vapor pressure deficits; and (iii) precipitation increases under 

water limited conditions (Fischlin et al., 2007).
85

TSD at 90. Thus, it appears that the Administrator’s statements on this issue fail to account for 

the full range of positive influences. 

The Administrator also ignores a singular benefit of increased forest growth: the 

correlated increase in CO2 sinks. The TSD states that “North American forests will absorb more 

CO2 and might retain more carbon as atmospheric CO2 increases.” Id. Neglecting these 

complex interactions skews the analysis of endangerment from GHG emissions and likewise 

feeds into what most likely are inaccurate projections of future GHG concentrations. EPA fails 

to address this important issue. 

Additionally, the section of the TSD addressing forest impacts indulges in speculation in 

the face of multiple uncertainties. For instance, the TSD cites as evidence for current climate 

change impacts that “[g]rowth is slowing in areas subject to drought.” Id. It is not at all 

established that this drought was caused by climate change or GHG emissions. Elsewhere, the 

document suggests that wildfires will pose the largest threat to forests over time. It notes, 

however, that wildfires and other extreme events are “not well represented in models” even as it 

suggests that wildfires will increase by as much as 10 percent. Id. at 92; see also id. at 93 

(noting that insect and pathogen outbreaks modeling also remains limited). Given that wildfires 

(and similar events) cannot be accurately modeled, it is unclear how the TSD arrives, or could 

arrive, at such a specific projection. Indeed, a recent scientific study ignored by EPA has found 

that past climate change has not been directly linked to increases in wildfires, that a variety of 

other factors are instead more closely related to increases in wildfire events, and that climate 

interactions with other factors can override any influence of climate change on wildfire events. 

Higuera, et al., Vegetation Mediated the Impacts of Postglacial Climate Change on Fire Regimes 

in the South-Central Brooks Range, Alaska, 79 ECOLOGICAL MONOGRAPHS 201-19 (2009). For 
86

instance, the TSD states that forest productivity impacts due to climate change are “difficult to 

separate . . . from other potentially influencing factors, particularly because these interactions 

vary by location.” TSD at 89. This, however, is precisely the sort of information needed in any 

rational evaluation of the potential for endangerment, and the Agency’s suggestion that these 

impacts result from climate is speculative and wholly unsupportable. 

Finally, this section of the Endangerment TSD suggests that changing forestry conditions 

in the United States might place it at a competitive disadvantage with other nations that will 

experience more positive effects from climate change. The document does not, however, attempt 

to analyze this issue at any useful level of detail. Further, no other sections of the TSD address 

the international competitiveness issue. If, as seems probable, the United States is likely to be 

placed at a competitive advantage to other nations as a result of other effects of climate change, 

those possible benefits to the United States should equally be reflected in the document. Failure 

to address this matter even-handedly contributes to the bias exhibited by EPA’s analysis.

e. Water Resources

Regarding water resources, the Administrator proposes to find that “[c]limate change will 

likely further constrain already over-allocated water resources in some sections of the U.S., 

increasing competition among agricultural, municipal, industrial, and ecological uses.” 74 Fed. 

Reg. 18902/2-3. She notes that “current water management practices in the U.S. are generally 

advanced, particularly in the West,” id. at 18902/3, but concludes that “climate change 

increasingly creates conditions well outside of historical observations,” id., and that drought “is 

expected to increase in the western U.S., where water availability to meet demands for 

agricultural and municipal water needs is already limited,” id. at 18900/1. In addition, the 

Administrator proposes to find that lower water levels in lakes and rivers “are likely to 

exacerbate challenges relating to water quality, navigation, recreation, hydropower generation, 
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water transfers, and binational relationships,” id., that “[h]igher water temperatures, increased 

precipitation intensity, and longer periods of low flows can exacerbate many forms of water 

pollution,” id., and that “[r]ising sea levels could lead to salt water intrusion of coastal ground 

aquifers, which would further reduce freshwater availability for municipal and agricultural use 

among coastal communities that depend on these aquifers,” id. at 18900/1-2.

As with the other public health and welfare issues addressed in these comments, the 

Administrator’s conclusions and the TSD passages addressing water resources require

reassessment in light of new scientific findings. Moreover, although the TSD notes potential 

negative impacts on water quality and supply from population increases, TSD at 94, and states 

that water shortages will be influenced by “changes in withdrawals (reflecting development, 

demand, and availability of other sources),” id. at 96, these influences are independent of climate 

change and cannot properly be considered in assessing endangerment. Their inclusion further 

undermines the document’s usefulness as support for any endangerment finding. 

Similarly, scientific clarity is compromised by this TSD section’s treatment of various 

uncertainties and its tendency to engage in speculation. Specifically, the document 

acknowledges that data on existing groundwater supplies are “limited,” yet, in the face of this 

lack of information, EPA proceeds to reach a number of conclusions about purported 

groundwater impacts. Id. Additionally, this section of the document argues that extreme 

weather events will negatively affect water resources by allowing salt water intrusion into fresh 

groundwater, increasing water pollution levels and negatively affecting water supplies. The TSD 

fails to note, however, that modeling of extreme events is plagued by significant uncertainties, as 

discussed above, even though this information is included in other sections. 
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Finally, this section of the TSD fails to acknowledge and quantify clear beneficial effects 

even as it describes asserted negative effects associated with the source of the benefits. The 

TSD, for instance, notes that certain water bodies will likely experience increased navigability as 

a result of climate change, but the document fails to quantify this benefit or to compare its 

relative value to decreases in navigability elsewhere. Id. at 99. Similarly, other sections of the 

TSD specifically note the sophisticated water treatment infrastructure and regulatory structures 

in place in the United States. See, e.g., id. at 73. Yet this key section, which is supposed to 

assess potential impacts on water resources, fails to address how climate change impacts would 

be moderated through implementation of existing laws, such as the Safe Drinking Water Act and 

the Clean Water Act. Given that EPA is charged with implementing these laws, EPA would 

need to evaluate whether they will effectively avoid all or portions of any projected negative 

impacts.

f. Sea Level Rise and Coastal Areas

The Proposed Endangerment Finding contains a number statements related to sea level 

rise and coastal areas:

Coastal communities and habitats will be increasingly stressed by climate change 

impacts interacting with development and pollution. Sea level is rising along 

much of the U.S. coast, and the rate of change will increase in the future, 

exacerbating the impacts of progressive inundation, storm-surge flooding, and 

shoreline erosion. Coastal aquifers and estuaries are vulnerable to salt water 

intrusion due to rising sea levels, which could compromise water sources used for 

municipal drinking water, agricultural crops, and other human uses. Storm

impacts are likely to be more severe, especially along the Gulf and Atlantic 

coasts. Salt marshes, other coastal habitats, and dependent species are threatened 

by sea-level rise, fixed structures blocking landward migration, and changes in 

vegetation. Population growth and rising value of infrastructure in coastal areas 

increases vulnerability to climate variability and future climate change.

74 Fed. Reg. at 18902/3.
89

Thus, the Administrator proposes to reach a number of highly problematic conclusions

with respect to coastal impacts. As stated above, the severity and rate of sea level rise is 

significantly overestimated in the EPA’s scientific assessment. This means that related impacts, 

such as flooding, shoreline erosion, and salt water intrusion, are also overstated. 

The TSD section addressing sea level rise and coastal areas also includes discussion of 

various impacts on and problems facing coastal areas that are not necessarily linked to climate 

change or even to sea level rise. See, e.g., TSD at 100 (discussing coastal areas stressed by 

development and pollution), 101 (discussing ‘coastal squeeze’ and its effects on wetlands), 101

(discussing erosion in the Great Lakes, where sea level rise “is not a concern”). 

Moreover, as the TSD indicates, “[a]lthough climate change is impacting coastal systems, nonclimate human impacts have been more damaging over the past century.” Id. at 100-01

(emphasis added).

Thus, it appears that the evidence EPA presents related to coastal impacts due to climate 

change is significantly overstated to the extent these other effects are not effectively 

distinguished from climate change-related impacts. These issues are improper for inclusion in an 

assessment of possible endangerment from GHGs.

g. Energy, Infrastructure, and Settlements

The Administrator proposes to conclude that “[c]limate change is likely to affect U.S. 

energy use (e.g., heating and cooling requirements), and energy production (e.g., effects on 

hydropower), physical infrastructures and institutional infrastructures. Climate change will 

likely interact with and possibly exacerbate ongoing environmental change and environmental 

pressures in settlements, particularly in Alaska where indigenous communities are facing major 

environmental changes from sea ice loss and coastal erosion that threaten traditional ways of 

life.” 74 Fed. Reg. at 18902/3-18903/1.
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These statements in the Proposed Endangerment Finding are exceptionally vague. It is 

completely unclear from those statements whether EPA views the effects it describes as positive 

or negative; indeed, it is unclear exactly what the effects may be at all. The TSD section 

describing these effects provides somewhat more detail on the relevant science but is flawed in 

the ways identified below (and also fails to meet the overarching need, discussed above, for the 

PSD to reassess projections of climate change and its effects based on new scientific studies). 

This section of the TSD engages in speculation that is unsupported by the science and 

overstates the likely impact of climate change. For instance, the document acknowledges that 

industries and settlements “have become resilient to” variability in climate conditions but follows 

up this statement by suggesting that variability caused by climate change will be greater than the 

capacity to adapt. TSD at 105. In the absence of evidence, this assertion is unwarranted. 

Similarly, the TSD notes that “it is not possible to attribute the occurrence of any singular [sic]

hurricane to climate change,” yet it engages in an indirect but speculative attempt to make such 

an attribution when it suggests that energy-related impacts caused by Hurricanes Ivan, Katrina, 

and Rita are “indicator[s] of the kinds of impacts that could manifest as a result of climate 

change (CCSP, 2007a).” Id. at 107. Moreover, as demonstrated above, projections of hurricanes 

and other extreme events are subject to greater uncertainties than the TSD generally 

acknowledges. 

This section of the TSD also unjustifiably favors study results that suggest impacts will 

be significant over those that predict the opposite. This is especially problematic in the 

document’s discussion of energy use for heating and cooling. The weight of the evidence on this 

issue indicates that overall energy use will not increase substantially because increases and 

decreases will generally net out. Id. at 105. The TSD acknowledges that changes in energy 
91

consumption will vary region to region and that overall effects on energy consumption are not 

clear. Id. (“Generally speaking, the net effects of climate change in the U.S. on total energy 

demand are projected to amount to between perhaps a 5% increase and decrease in demand per 

1oC in warming in buildings. Existing studies do not agree on whether there would be a net 

increase or decrease in energy consumption with changed climate because a variety of 

methodologies have been used (CCSP, 2007a).”). Despite these uncertainties, the TSD 

improperly emphasizes one study that predicts a significant increase in electricity demand 

requiring substantial investment in new generation. EPA gives no reason for singling out this 

one study for deference. Indeed, EPA apparently has not evaluated this study itself and only 

refers to a CCSP synthesis report that apparently cites it. Id. at 106. Where one study is --

without explanation -- given special weight, it is an especially egregious error to fail to assess it

with reasonable clarity. EPA also fails to justify its decision to deemphasize the greater body of 

science on this issue.

Similar problems undermine the TSD’s assessment of asserted climate change-related 

impacts on transportation resources and human settlements. As with energy production, the TSD 

states that these resources will primarily be affected by “weather and climate extremes, such as 

very hot days; intense precipitation events; intense hurricanes; drought; and rising sea levels, 

coupled with storm surges and land subsidence.” Id. at 109; see also id. at 111. First, land 

subsidence plainly is not a climate change-related influence. More broadly, any asserted impacts 

that EPA tries to trace to climate change effects would have to be reassessed based on the flaws 

described above in EPA’s analysis of those effects. Further, this section of the TSD 

acknowledges that adaptive capacity is a significant factor in determining the severity of impacts 

to human settlements. Id. at 111. Because the Agency improperly omits analysis of adaptation 
92

from its assessment of endangerment, however, the TSD’s conclusion with respect to these 

effects is incomplete and inaccurate.

h. Ecosystems and Wildlife

The Administrator proposes to find that “changes in climate will cause some species to 

shift north and to higher elevations and fundamentally rearrange U.S. ecosystems. Differential 

capacities to adapt to range shifts and constraints from development, habitat fragmentation, 

invasive species, and broken ecological connections will alter ecosystem structure, composition, 

function, and services.” 74 Fed. Reg. at 18903/1. In addition to the overarching concerns 

resulting from the need for reanalysis of earlier modeling results, these conclusions and the 

TSD’s analysis of these issues are marked by several specific shortcomings.

A number of problems with EPA’s analysis of ecosystem and wildlife impacts have led to 

misguided conclusions in the Proposed Endangerment Finding. First, the TSD describes possible 

effects on plant phenology, such as the onset of greenness and leaf senescence. TSD at 113. 

EPA offers no basis, however, for judging whether these effects are positive, negative, or neutral. 

The same is true with respect to similar life-cycle issues for animal species. See id. at 114. EPA 

speculates that these changes “may shift out of sync, causing species to become decoupled from 

their resource requirements.” Id. It further speculates that “the decline of long-distance 

migratory birds in the United States may originate in mistiming of breeding and food abundance 

due to differences in phenological shifts in response to climate change (Scott et al., 2008).” Id. 

EPA provides no assessment of the evidence supporting these assertions, which appear to be 

mere guesses. These unsupported “effects” are not a basis for an affirmative endangerment 

finding. Similarly, the TSD states that there will be increases in global likelihood of species 

extinctions and that 20 to 30 percent of species globally will be at risk. Id. at 117. The 

document notes, however, that such risk varies regionally and includes percentages as low as 1
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percent, id., and EPA again fails to identify the risk levels applicable in the United States, a 

failing that makes this information useless in a CAA endangerment assessment.

The TSD also describes potential range shifts for various plant and animal species. It 

states that “[m]igrating to higher elevations with more suitable temperatures can be an effective 

strategy for species if habitat connectivity exists and other biotic and abiotic conditions are 

appropriate.” Id. at 114. The TSD further states, however, that “many organisms cannot shift 

their ranges fast enough to keep up with the current pace of climate change (Fischlin et al., 

2007).” Id. This statement suggests that adaptive capacities are limited and will result in species 

loss. That some (but not all) species will have migration as an option for adaptation does not 

however, support a conclusion that species will be unable to adapt in other ways. Similarly, the 

TSD describes a number of ecosystem changes that may occur in certain regions and localities in 

the United States. Id. (discussing frog breeding in upstate New York), 115 (discussing changes 

in marine mammal and pelagic fish populations in the Southeastern Bering Sea). Again, EPA 

provides no basis for concluding whether these effects will actually be negative. Indeed, 

reference to changes at specific locations overlooks the potential for offsetting changes in other 

regions and localities. EPA cannot conclude that ecosystem changes will result in overall 

negative effects without thoroughly examining ecosystem changes throughout the nation. 

Further, the Agency must acknowledge and explain the significant limitations in regional-scale 

modeling and the implications of these limitations for EPA’s conclusions. 

Regarding marine organisms and ecosystems, the TSD states that “human impacts such 

as overfishing, pollution, and the introduction of invasive species” negatively affect these 

resources and may exacerbate any problems that result from climate change. These effects, 

however, will occur regardless of whether climate change results in any additional impacts to 
94

marine organisms and ecosystems, and they are therefore inappropriate considerations in an 

assessment of possible endangerment from GHG emissions. Id. at 114. 

The TSD also projects that climate change will result in decreased biodiversity. The 

science in this area is particularly uncertain, however, and even the studies EPA cites indicate 

that there may be long-term positive developments in species richness. Id. at 117, 118 (noting 

lack of information regarding numerous species). Further, as noted above, recent studies indicate

that biodiversity impacts and invasive species propagation will be limited. In addition, the 

document cites the IPCC for the conclusion that ocean acidification will result in declines in 

carbonate-based marine organisms, such as corals, due to reduced aragonite needed for 

biocalcification. Id. at 114. The IPCC, however, concluded with only medium confidence that 

that increased CO2 levels in conjunction with climate change could have negative impacts on 

these same marine organisms. Working Group II Ch. IV at 213, 234, Fischlin A. et al., 2007.

The TSD improperly fails to reflect accurately the uncertainties and limitations embedded in its 

source material. 

4. International Impacts

As noted above, the TSD devotes substantial space to discussion of global emissions and 

global effects of climate change, often commingling discussion of these effects with discussion 

of U.S. impacts in a manner that prevents accurate assessment of the effects of climate change on 

U.S. resources alone. Beyond this, the Administrator and the TSD both address international 

impacts separately from U.S. effects. The Administrator states that her proposed endangerment 

finding is warranted based only on the health and welfare effects projected to occur in the United 

States. She further states: “In addition, the scientific evidence concerning risks and impacts 

occurring outside the U.S., including risks and impacts that can affect people in the U.S., 

provides further support for this finding.” 74 Fed. Reg. at 18888/1.
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The analysis of international issues presented in the TSD is wholly unscientific and 

cannot provide any support for an endangerment finding. In general, the TSD discusses potential 

effects of climate change in other nations, focusing particularly on areas EPA characterizes as 

vulnerable, including Africa, Asia, Latin America, Polar Regions, and Small Islands. It asserts 

that climate change will affect the health of people, food production, and water resources in these 

regions and could influence international trade. TSD at 125-28. Although scientific evidence 

exists on potential impacts of climate change in foreign nations, these impacts are not directly 

relevant to an endangerment assessment. Moreover, EPA’s attempt to tie foreign effects to the 

United States by noting the potential international trade effects of climate change fails because, 

as EPA concedes, “[t]here is currently a lack of information about how these potential impacts in 

other regions of the world may influence international trade and migration patterns.” Id. at 125.

The TSD likewise fails to establish that foreign impacts will affect U.S. interests in other 

ways. Again, EPA suggests vaguely that foreign climate change impacts “may have 

consequences that transcend national boundaries that raise concerns for the U.S.” Id. at 2. The 

only “evidence” of additional transcendental consequences to which EPA can point, however, is 

derived from non-scientific sources that are inherently speculative. The TSD cites, for instance, 

a Defense Department report concluding that climate change could potentially destabilize global 

geopolitics. Id. at 123. The TSD also cites a report suggesting that opening Arctic sea routes 

could raise questions about sovereignty rights in the Arctic. Id. Moreover, it cites a report 

detailing the opinions of 12 retired generals and admirals regarding possible threats climate 

change could pose to national security. Id. at 124. Resort to this unscientific, speculative grabbag reflects EPA’s unjustifiable attempt to expand the scope of its endangerment assessment to 

encompass issues that are not shown to impact U.S. public health and welfare. Indeed, the TSD 
96

notes that neither the IPCC nor the CCSP -- on which EPA otherwise heavily relies -- has

“explicitly addressed these issues.” Id. at 6.

VI. The Proposed Endangerment Finding and the TSD Fail To Comply with the Data 

Quality Act.

When President Obama appointed Administrator Jackson to lead EPA, she pledged that 

all of EPA’s efforts would be “rooted in three fundamental values: science-based policies and 

programs, adherence to the rule of law, and overwhelming transparency.”20 In a memorandum to 

EPA staff issued shortly after her Senate confirmation, Administrator Jackson explained these 

three values further, expressing the importance of “rigorous adherence to the best available 

science,” observing that, while policy judgments are required for the proper implementation of 

law, “policy decisions should not be disguised as scientific findings,” and reminding Agency 

staff that “[p]ublic trust in the Agency demands . . . that we fully disclose the information that 

forms the bases for our decisions.”21 More recently, in EPA’s Semiannual Regulatory Agenda, 

she reiterated EPA’s commitment to these three principles.22

Sadly, in the Proposed Endangerment Finding and its accompanying TSD, EPA has 

missed an opportunity to put these principles into practice. Indeed, EPA here falls far short of 

the Administrator’s stated goals. And, more significant from a legal standpoint, EPA has 

violated the DQA,

23 the guidelines set forth by the Office of Management and Budget to 

20 Statement by Administrator-designate Lisa Jackson (Jan. 23, 2009), available at

http://yosemite.epa.gov/opa/admpress.nsf/0/2297C12A9F4773D285257547006497D4.

21 Memo to EPA Employees from Administrator Lisa P. Jackson (Jan. 23, 2009), available at

http://www.epa.gov/administrator/memotoemployees.html. 

22 74 Fed. Reg. 21992, 21993/1 (May 11, 2009).

23 Treasury and General Government Appropriations Act for Fiscal Year 2001, Pub. L. No. 106-

554, § 515 (Dec. 21, 2001), 114 Stat. 2763.
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implement the DQA (“OMB Guidelines”),

24 and EPA’s own DQA guidelines (“EPA 

Guidelines”).25

The DQA and the OMB Guidelines require federal agencies, including EPA, to issue 

guidelines ensuring and maximizing the quality, objectivity, utility, and integrity of all 

information disseminated by the agency and establishing administrative procedures allowing 

affected parties to request and obtain correction of any disseminated information that fails to 

comply with those guidelines. EPA has published guidelines that closely track the language in 

the OMB Guidelines.

The OMB and EPA Guidelines define dissemination of information as any distribution of 

information to the public that is initiated or sponsored by the agency,

26 including distribution of 

information prepared by a party outside the agency in a manner that suggests the agency intends 

to endorse or agree with that information.27 The term “quality” broadly encompasses the 

standards of objectivity, utility, and integrity.

28 The standard of objectivity refers to information 

that is “presented in an accurate, clear, complete and unbiased manner.”29 The standard of utility 

refers to “the usefulness of the information to its intended users, including the public.”30 The 

24 67 Fed. Reg. 8452 (Feb. 22, 2002).

25 U.S. EPA Office of Environmental Information, “Guidelines for Ensuring and Maximizing the 

Quality, Objectivity, Utility, and Integrity of Information Disseminated by the Environmental 

Protection Agency,” EPA/260R-02-008 (Oct. 2002).

26 67 Fed. Reg. at 8460/2-3; EPA Guidelines at 15. 

27 EPA Guidelines at 16; see also 67 Fed. Reg. at 8454/1.

28 67 Fed. Reg. at 8459/2; EPA Guidelines at 15.

29 67 Fed. Reg. at 8459/3; EPA Guidelines at 15.

30 67 Fed. Reg. at 8459/2; see also EPA Guidelines at 15.
98

standard of integrity refers to the security of the information, meaning its protection from 

unauthorized access or revision.31

In compliance with the OMB Guidelines, the EPA Guidelines impose heightened 

standards for the quality of “influential information,” which is defined as information that the 

Agency anticipates “will have or does have a clear and substantial impact . . . on important 

public policies or private sector decisions.”32 Influential information is to be disseminated with a 

higher-than-usual degree of transparency with respect to: “(1) the source of the data used, (2) the 

various assumptions employed, (3) the analytic methods applied, and (4) the statistical 

procedures employed,” in order to “facilitate the reproducibility of such information by qualified 

third parties, to an acceptable degree of imprecision.”33 Among the classes of information 

deemed “influential” by EPA is information that is “disseminated in support of top Agency 

actions,” such as rules, substantive notices, and policy documents.34 Undoubtedly, the Proposed 

Endangerment Finding and the TSD on which it relies fall into this category, as these documents 

would form the basis for the unprecedented regulation of GHG emissions under the CAA. In 

addition, as described further below, the EPA Guidelines impose special requirements for the 

quality of science used in risk assessments. 

31 67 Fed. Reg. at 8460/2; EPA Guidelines at 15.

32 EPA Guidelines at 19.

33 Id. at 20-21. 

34 Id. at 20. 
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Despite assurances from EPA to the contrary,

35 it is clear that the TSD on which the 

Proposed Endangerment Finding is based fails to comply with OMB and EPA Guidelines for 

dissemination of influential information. Specifically, as described in the sections below, EPA 

has failed to comply with the requirements that it: (1) undertake an independent external peer 

review of the TSD; (2) provide information that is reproducible; and (3) use only the best 

available science. In accordance with the procedures set out in the EPA Guidelines,36 UARG 

respectfully submits a Request for Correction of information in the TSD with respect to each of 

these three issues and reserves its right to file a Request for Reconsideration of any refusal by the 

Agency to make corrections or any inadequate correction by the Agency, pursuant to section 8.6 

of the EPA Guidelines.37 UARG has an interest in ensuring that the TSD, which forms the basis 

for the Proposed Endangerment Finding, is accurate. A final endangerment finding by EPA 

would raise issues concerning requirements for stationary sources, including electric generating 

units such as those operated by UARG members, under the CAA. UARG members will benefit 

from ensuring that any finding by EPA with regard to the question of endangerment rests on 

sound scientific principles.

35 Both the TSD and the Proposed Endangerment Finding state that the information in the TSD 

complies with the EPA Guidelines. TSD at 4; 74 Fed. Reg. at 18894/1.

36 See EPA Guidelines at 30-33. Section 8.5 of the EPA Guidelines states that any Request for 

Correction of disseminated information for which a public comment period is provided should be 

addressed using the public comment process. See id. at 32.

37 Id. at 34.
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A. Inadequate Peer Review

EPA requires independent external peer review in accordance with EPA’s Peer Review 

Handbook (the “Handbook”)38 of influential information such as that in the Proposed 

Endangerment Finding and the TSD.39 The Handbook explains that peer reviewers are to be 

individuals or organizations “who are independent of those who performed the work” to be 

reviewed40 and who are unbiased and do not “have a material stake in the outcome of the peer 

review.”41 It explains further that “EPA should always make every effort to use peer reviewers 

who do not have any conflict of interest or an appearance of a lack of impartiality, and who are 

completely independent.”42 Although many qualified experts were available to serve as 

reviewers of the TSD, EPA chose external reviewers who were likely in favor of the conclusions 

stated in the Proposed Endangerment Finding. 

All 12 reviewers for the TSD are scientists employed by the federal government. One is 

an EPA scientist. Each of the reviewers is closely affiliated with the CCSP and has openly and 

publicly articulated his or her belief that GHGs create dangers for public health and welfare. 

Seven of the 12 reviewers authored studies that are cited in the TSD; several of those studies are 

cited extensively and relied on by the TSD. 

38 U.S. EPA Science Policy Council, “U.S. Environmental Protection Agency Peer Review 

Handbook” (3d ed.), EPA/100/B-06/002 (May 2006).

39 EPA Guidelines at 11; EPA Peer Review Policy, available at http://www.epa.gov/OSA/spc/

2peerrev.htm.

40 Handbook at 12.

41 Id. at 13.

42 Id. at 60.
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Thus, none of the reviewers chosen by EPA could be expected to provide a critical, 

independent, and objective peer review of the TSD. EPA’s failure to subject the TSD to

independent external peer review violates the DQA and the EPA Guidelines. Therefore, 

UARG’s first Request for Correction is a request that EPA submit the TSD to independent 

external peer review pursuant to the Handbook, as required by the EPA Guidelines.

B. Lack of Transparency

As described above, the EPA Guidelines set especially strict requirements for 

transparency when the Agency disseminates influential information such as that in the TSD and 

the Proposed Endangerment Finding. The purpose of this heightened level of transparency is to 

allow for reproducibility by qualified members of the public.43 The OMB Guidelines explain in 

greater detail that agency guidelines are to “require sufficient transparency about data and 

methods that an independent reanalysis could be undertaken by a qualified member of the public

. . . [whether] agency analysis [is] of data from a single study . . . [or] combine[s] information 

from multiple studies.”44 The OMB Guidelines explain, and the EPA Guidelines acknowledge, 

that agencies may deviate from this requirement only in cases where a “compelling interest,” 

such as “privacy, trade secrets [or] intellectual property,” requires that transparency be limited.45

In cases where transparency is limited by a compelling interest, the agency is required to “apply 

especially rigorous robustness checks to analytic results and document what checks were 

undertaken.”46 The OMB Guidelines state that in every case, agency guidelines are to require 

43 EPA Guidelines at 20-21. 

44 67 Fed. Reg. at 8460/1. 

45 Id.; EPA Guidelines at 21.

46 67 Fed. Reg. at 8460/1; see also EPA Guidelines at 21. 
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“disclosure of the specific data sources that have been used and the specific quantitative methods 

and assumptions that have been employed.”47 EPA has failed to fulfill these transparency

requirements in the TSD and the Proposed Endangerment Finding. 

EPA has not provided access or reference to any raw data or to any data source and has 

not described the methods and assumptions it used to analyze the information it relied on for the 

conclusions in the Proposed Endangerment Finding. This is likely due, at least in part, to EPA’s 

heavy reliance on reports by the CCSP and the IPCC. Over two-thirds of the citations in the 

TSD are to reports published by or in connection with one of these groups or the National

Research Council, and only a small fraction of the remaining one-third are references to 

independent studies or journal articles. Most of the remaining references are to reports or online 

statistical compilations by EPA and other federal agencies. EPA explains in the Proposed 

Endangerment Finding that it chose to rely on reports by the IPCC and the CCSP “rather than 

conducting a new assessment of the scientific literature” and that it views the IPCC in particular 

as a “benchmark” against which it plans to judge future research and findings.48 Transparency 

is, therefore, limited by EPA’s decision to adopt the reports of the IPCC and the CCSP instead of 

developing its own position based on independent scientific research. 

Yet, neither the TSD nor the Proposed Endangerment Finding describes any type of 

checks undertaken by EPA to evaluate the scientific data on which the IPCC and CCSP reports 

were based, or indicates whether EPA reviewed or even had access to those underlying data. 

The TSD says that IPCC reports are based “mainly on peer reviewed and published 

47 67 Fed. Reg. at 8460/1. 

48 74 Fed. Reg. at 18894/1. 
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scientific/technical literature” and that they are subject to expert and governmental review.49 the 

TSD also says that CCSP reports are subject to expert, interagency, and public review and that 

final reports issued by CCSP comply with the DQA.50 EPA’s explanations are aimed at 

indicating that, in EPA’s view, the information in the IPCC and CCSP reports are reliable; they 

do not indicate that EPA has reviewed or assessed the accuracy of the data underlying those 

reports. In fact, EPA states in the TSD that it chose to rely on these reports in part because the 

reports “have assessed numerous individual studies in order to draw general conclusions about 

the state of science.”51 This statement implicitly acknowledges that EPA relied on IPCC and 

CCSP assessments without reviewing the underlying data. 

Finally, documents such as the IPCC reports must satisfy DQA requirements if they are 

endorsed or relied on by EPA. The IPCC is not required, however, to comply with the DQA, and 

EPA has not shown that the IPCC’s information quality processes are equivalent to DQA

requirements. In fact, as discussed above, a review of IPCC policy and procedures reveals that 

preparation of IPCC reports is a highly bureaucratic political process aimed at forming 

governmental policies on climate change in the context of international negotiation. IPCC was 

formed for the purpose of providing policymakers with “an objective source of information 

about the causes of climate change, its potential environmental and socio-economic 

consequences and the adaptation and mitigation options to respond to it.”52 Lead authors for 

49 TSD at 3, Box 1.1 (emphasis added).

50 Id.

51 Id. at 5.

52 See “About IPCC” on the IPCC website at http://www.ipcc.ch/about/index.htm.
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IPCC reports are chosen from lists supplied by governments and participating organizations.53

Drafts of the reports are reviewed by governments and experts selected by governments.54

Moreover, IPCC reports examine global effects of GHGs, and are not focused on conditions in 

the United States.55

EPA’s reliance on IPCC reports and its failure either to provide access to the data and 

methods used to form its conclusions, or to perform and document the rigorous reliability check 

required in cases where transparency is limited, violate the DQA, the OMB Guidelines, and the 

EPA Guidelines. UARG’s second Request for Correction is that EPA: (1) provide all of the 

information on which EPA relied in the TSD and the Proposed Endangerment Finding, along 

with an explanation of the methods and assumptions used to analyze that information; (2)

describe each compelling interest that precluded EPA from disclosing any of the information that 

it withheld; and (3) fully document the rigorous robustness check undertaken to assess any 

information that it has withheld. 

C. Failure To Use Best Available Science 

As mentioned above, the EPA Guidelines place special requirements on influential 

scientific information used in human health, safety, or environmental risk assessments. For these 

assessments, EPA adapted the information quality principles set forth in the Safe Drinking Water 

53 Procedures for the Preparation, Review, Acceptance, Adoption, Approval and Publication of 

IPCC Reports (App. A to the Principles Governing IPCC Work) § 4.2.2, available at

http://www.ipcc-wg2.gov/AR5/extremes-sr/extremes_documents/ipcc-principles-appendix-a.pdf 

(hereinafter “IPCC Procedures”). 

54 Id. § 4.2.4.

55 See section V.B.
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Act Amendments of 1996.56 These requirements state that the influential information must be 

“accurate, reliable and unbiased” and must employ “the best available science and supporting 

studies” and “data collected by accepted methods or best available methods.”57 In addition, the 

presentation of the influential information must specify each of the following: (1) each 

population affected by each risk assessed; (2) the expected risk for each affected population; (3) 

each appropriate upper- or lower-bound estimate of risk; (4) each significant uncertainty 

identified by the risk assessment and studies that may assist in resolving the uncertainty; and (5) 

peer-reviewed studies “that support, are directly relevant to, or fail to support” any risk 

assessment and methodologies used to reconcile any inconsistencies in the scientific data.58

As described in greater detail in section V of these comments, the science that EPA used 

for the TSD and the Proposed Endangerment Finding fails to meet these requirements. For 

example, the TSD ignores information relevant to adaptation and fails to distinguish among

climate effects.59 Such omissions and other shortcomings reduce the accuracy of the science that 

is presented and result in an exaggerated assessment of risk. The TSD relies on reports by the 

CCSP and the IPCC, which fail to address adequately issues relevant to conditions in the United 

States and under the CAA.60 This is a clear failure to employ the best available science. The 

Proposed Endangerment Finding fails to explain adequately the basis for the Administrator’s 

56 Safe Drinking Water Act Amendments of 1996, Pub. L. No. 104-182, 110 Stat. 1613 (Aug. 6, 

1996). 

57 EPA Guidelines at 21-22. 

58 Id. at 22-23. 

59 See section V.A.

60 See section V.B.
106

conclusion regarding the effects of GHG emissions on public health and welfare61 and fails to 

consider a number of recent studies that contradict or challenge EPA’s conclusions in the 

Proposed Endangerment Finding.62 These deficiencies constitute a violation of the requirements 

regarding presentation of influential information established by the EPA Guidelines. Therefore, 

UARG’s third Request for Correction is that EPA amend the TSD and the Proposed 

Endangerment Finding to reflect reliance on the best available science, specifically resolving the 

scientific shortcomings noted in this paragraph and discussed in section V of these comments.

VII. EPA Has Not Presented a Proper Contribution Analysis for Public Comment.

As noted above, any “contribution” analysis under section 202(a)(1) of the Act should 

address the contribution of emissions from the relevant U.S. sources to total worldwide GHG 

emissions and atmospheric concentrations. Because the stated purpose of this proceeding is to 

address contributions to what EPA characterizes as air pollution that consists of global

atmospheric concentrations of certain gases, it makes no sense to assess U.S. emissions of the 

sources to be regulated in relation to all U.S. emissions, with respect to either a single GHG or all 

six GHGs in the aggregate. 

Moreover, the relevant emissions to be assessed in the contribution analysis are those 

from new U.S. motor vehicles only, not from all U.S. motor vehicles. The emission percentage 

that EPA cites (4.3%) reflects emissions from all section 202(a)(1) sources, not emissions from 

that subset of section 202(a)(1) sources, i.e., new vehicles, that EPA is authorized to regulate. 

Moreover, EPA should further refine the contribution assessment to address those categories of 

new section 202(a)(1) sources whose GHG emissions it plans to address through regulation. 

61 See section V.C.

62 See section V.D.
107

Thus, for the reasons discussed in section II of these comments, the contribution assessment 

should address new U.S. section 202(a)(1) vehicles to be manufactured in model years 2012 

through 2016, other than motorcycles, buses, and heavy- and medium-duty trucks.

Finally, EPA properly acknowledges that “any finding of a ‘contribution’ requires some 

threshold to be met; a truly trivial or de minimis ‘contribution’ might not count as such.” 74 Fed. 

Reg. at 18892/2-3. EPA says that it “need not determine at this time the circumstances in which 

emissions would be trivial or de minimis and would not warrant a finding of contribution.” Id. at 

n.14. Yet EPA also states that, where “[m]ethane emissions from Section 202(a) source 

categories were less than 0.01 percent of total global greenhouse gas emissions in 2005” (and 

where, of course, the methane emissions from only the new section 202(a) sources in categories 

that EPA actually would regulate would constitute an even smaller percentage of that total), EPA 

would deem even that vanishingly small portion of emissions to “contribute” within the meaning 

of section 202(a)(1). EPA’s implicit determination that a share of total emissions of less than 

one one-hundredth of one percent is not “trivial or de minimis” is, on its face, inconsistent with 

EPA’s suggestion that it would apply a de minimis exception under section 202(a)(1). More 

fundamentally, that determination reflects an incoherent and internally inconsistent approach by 

EPA in this proceeding to the question of what constitutes a statutorily cognizable 

“contribution.” 

VIII. If EPA Decides To Promulgate Final Motor Vehicle GHG Rules, Regulation of 

Many Previously Unregulated Sources Will Result.

If EPA makes the Proposed Endangerment Finding final, this action would affect more 

than the new motor vehicles whose GHG emissions EPA would be required to regulate under 

section 202(a) of the Act. As EPA recognized in the ANPR, “if EPA were to regulate 

greenhouse gas emissions from motor vehicles under the Clean Air Act, then regulation of 
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smaller stationary sources that also emit GHGs – such as apartment buildings, large homes, 

schools and hospitals – could also be triggered” through the Act’s PSD program. 73 Fed. Reg. at 

44355/1. The potential for regulation of GHGs under the PSD program presents an enormous 

challenge for EPA and the nation.

In examining whether GHGs endanger public health and welfare, EPA should recognize 

that a healthy economy and the ability to provide good jobs with fair wages is absolutely the 

most critical item in assuring the protection of our nation’s health and welfare. In assessing 

whether to find that GHGs endanger public health and welfare, EPA should consider the 

regulatory consequences of such a decision, including the negative impact on the nation’s 

economy that could result from regulation of GHGs through the PSD program and the Title V 

program. The imposition of these programs on all sectors of the nation’s economy, which may 

very well be required if EPA makes final the Proposed Endangerment Finding, may very well 

create economic gridlock where commerce cannot implement the normal, routine changes 

needed to respond to growth or changes in demand. Such economic gridlock will adversely 

affect public health and welfare.

The CAA requires owners and operators of major stationary sources of air pollution to 

obtain construction permits before building or modifying those sources. Although PSD 

primarily applies to criteria air pollutants for which a NAAQS has been established, PSD can 

also apply to CAA-regulated pollutants for which there is no NAAQS. If EPA decides to 

propose and promulgate a rule establishing limits on emissions of GHGs from motor vehicles, 

which it will have to do if it decides to make the Proposed Endangerment Finding final, that 

finding could result in PSD permits needing to provide that GHG emissions from PSD sources

are limited by any applicable “best available control technology” (“BACT”).
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Under the PSD program, a PSD permit is required for the construction or modification of 

any major stationary source that emits or has the potential to emit 250 tons per year of a 

regulated pollutant (or 100 tons per year for a source in a specifically listed category, including 

large fossil fuel-fired steam electric plants). Because many sources emit CO2, EPA noted in the 

ANPR that “many types of new small fuel-combusting equipment could become newly subject 

to the PSD program if CO2 becomes a regulated . . . pollutant.” Id. at 44498/3. Additionally, for 

sources already considered major sources, such as fossil fuel-fired power plants, regulation of 

CO2 likely would create the risk that many more changes could arguably be deemed major 

modifications. See id. at 44499/1. As an example, EPA notes that a hypothetical 500-megawatt 

electric utility boiler that burns bituminous coal and that is well-controlled for traditional air 

pollutants can emit more than 580 tons per hour of CO2. Id. At such a source, any change that 

otherwise qualifies as a modification under applicable NSR regulations and that results in just 10 

additional minutes of utilization over the course of a year could, at least in theory, result in a 

100-ton-per-year increase and thus could potentially trigger PSD requirements. See id.

In the ANPR, EPA estimated that approximately 200-300 PSD permits are issued 

nationally each year for construction of new sources and major modifications at existing sources. 

If CO2 were to become a regulated pollutant, which will eventually occur if EPA finalizes the 

Proposed Endangerment Finding, EPA estimated that the number of PSD permits required each 

year would increase by more than a factor of 10 (i.e., to more than 2000 to 3000 permits each 

year). Id. at 44499/1-2. UARG believes, however, that this is actually an underestimate because 

EPA failed to account for a source’s potential to emit year-round but instead based the estimate

on actual emissions. As EPA acknowledged in the ANPR, if year-round operation is assumed as 

the basis for estimating sources’ potential to emit, the actual number of PSD permits required 
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“would likely be an order of magnitude higher.” Id. at 44504/2. EPA’s sole reliance on actual 

emissions is misplaced, as EPA’s rules make clear that a source’s potential to emit applies in the 

case of new construction and for modifications where the existing facility has not begun normal 

operations. 40 C.F.R. § 52.21(b)(21).

In the ANPR, EPA also stated its belief that PSD program requirements become 

applicable on the effective date of the first regulation requiring GHG control under the Act. 73 

Fed. Reg. at 44500/1. UARG notes that exactly when a regulation becomes “effective” can vary 

depending on the CAA provision at issue. For example, section 202(a)(2) of the Act specifies 

that any section 202(a)(1) emission standard for new motor vehicles “shall take effect after such 

period as the Administrator finds necessary to permit the development and application of the 

requisite technology, giving appropriate consideration to the cost of compliance within such 

period.”

Any CAA regulation of a GHG for the first time would have to be coordinated carefully 

with a lawful and appropriate approach to PSD permitting, and EPA should consider the effects 

of regulation under the PSD program when it considers the Proposed Endangerment Finding and 

possible regulation of GHGs under the Act. In the ANPR, EPA stated that this type of 

coordination would be “necessary to minimize confusion on the part of sources, permitting 

authorities, and the public, to provide for as effective a transition as possible, and to ensure that 

the strategies intended to avoid problems can be in place in time to prevent those problems.” Id. 

at 44510/1. Given the importance of the issue, EPA should consider carefully not only the nature 

but also the timing of any regulation of GHGs under the CAA if it decides to finalize the 

Proposed Endangerment Finding. At the same time, EPA will be required to engage questions 

concerning whether, given the nature and scope of the impacts on the PSD program that would 
111

result from GHG regulation under emission control provisions of the Act such as section 202(a), 

Congress intended any such GHG regulation to occur at all. 

In the ANPR, EPA discussed the possibility of some alternatives, under which, it 

suggests, it might be possible to mitigate the impact of PSD regulation on a variety of sources.

Id. at 44503/2. To the extent EPA believes it can propose alternatives to ease this regulatory 

burden, it would have to provide in any notice of proposed rulemaking a complete and adequate 

explanation of the authority it believes it has to accomplish this and of how its action on this 

matter would not conflict with positions previously taken by the Agency or the courts. Although

some environmental groups have suggested that EPA may have broad administrative or 

regulatory flexibility to mitigate or even avoid these burdensome effects, these statements 

conflict with past statements made by those groups. For example, in the past, environmental 

organizations and others have argued that EPA cannot issue general permits for PSD and that 

BACT determinations must be made on a case-by-case basis. See, e.g., Statement of David 

Hawkins, Natural Resources Defense Council (“NRDC”) (stating that proposed utility BACT 

presumption for NOx emissions from modified electric utility steam generating units (proposed 

at 56 Fed. Reg. 27630, 27638 (June 14, 1991)) had “no legal basis” because “[t]he Act specifies 

that BACT control decisions must be made on a case-by-case basis”); Statement of Congressman 

Henry A. Waxman (stating, with regard to the same proposed utility BACT presumption, that 

“[i]t is highly unusual -- if not illegal -- for EPA to set a federal BACT presumption”). Thus, 

EPA would need to explain, in any proposed rulemaking addressing possible alternatives to 

mitigate the effect the PSD program could have if GHGs become regulated pollutants under the 

CAA, why those prior arguments are incorrect and why contrary views now expressed by certain 

representatives of those groups can be relied on with assurance. See, e.g., Massachusetts v. EPA 
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Part II: Implications of the Supreme Court Decision: Hearing Before the House Select 

Committee on Energy Independence and Global Warming, 110th Cong. (Mar. 13, 2008), 

Testimony of David Bookbinder, Chief Climate Counsel, Sierra Club, at 9 (“Bookbinder 

Testimony”) (arguing that a “possibility” to avoid the PSD problem would be to “allow[] for 

coverage of all sources below an individual permitting level (again, possibly 5-10,000 [tons per 

year]) to be covered by a general permit”). In addition, UARG notes that the thresholds for PSD 

applicability are written directly into the statute itself. If EPA decides to increase these 

thresholds to ensure that PSD applies only to “large” sources, it will need to justify its legal 

authority to take that step without express congressional approval. 

If EPA finalizes the Proposed Endangerment Finding, it is not only the PSD program that 

could lead to the potential regulation of numerous small stationary sources that are currently 

unregulated. Regulating GHGs, as will occur if the Proposed Endangerment Finding is finalized,

could result in numerous sources needing to obtain operating permits under Title V of the Act. If

EPA regulates GHG emissions under the Act, this could trigger a requirement that any source 

that emits at least 100 tons per year of one of those GHGs, including CO2, would need to apply 

for a Title V permit within one year of becoming subject to Title V requirements. The Title V 

permit for that source would include not only any applicable requirements for the GHGs but also 

requirements that apply to other pollutants such as generally applicable opacity limitations that 

exist in several state implementation plans. 

In the ANPR, EPA noted that the Title V permit program would bring in even more 

sources than the PSD program would because the 100-ton-per-year cutoff applies to all source 

categories, not only to categories specifically listed in the CAA. 73 Fed. Reg. at 44511/1. EPA 

estimated that more than 550,000 sources would require Title V permits if EPA regulates GHGs
113

under the CAA. Currently, there are approximately 15,000-16,000 Title V sources. Id. at

44511/1-2. EPA also expressed concern that Title V permits might have to be continually 

reopened as any GHG regulation takes effect under the Act. In the ANPR, EPA observed that 

there would be relatively little benefit from regulating these small sources because of the 

expected unavailability of add-on emission control devices at such sources and their relatively 

small emissions. Id. at 44512/2. Although UARG agrees that there may well be little 

demonstrable benefit from regulating these small sources, it notes that Congress enacted the 

requirements of the Title V operating permit in the Act, and EPA is bound to follow the 

directives of Congress. As with the PSD program, EPA described several alternatives in the 

ANPR that it suggested might address the burden of the Title V program in the GHG context. Id. 

at 44512/3-44513/1. Yet EPA has thus far failed to address the legal barriers that could prevent

EPA from implementing such alternatives.

With respect to both PSD and Title V, EPA would need, in any notice of proposed 

rulemaking for GHG regulation under the CAA -- including a notice of proposed rulemaking for 

new motor vehicle GHG emission standards under section 202(a) -- to address the specific basis 

for any authority it believes it may have to mitigate the dramatic and disruptive effects on these 

programs’ nature and scope that could result from any decision to finalize the Proposed 

Endangerment Finding.

IX. A Final Endangerment Finding with Respect to GHGs Under Section 202(a) of the 

CAA Would Not Satisfy the Prerequisites for Listing GHGs as Criteria Air 

Pollutants Under Section 108 of the Act.

Section 108(a)(1) of the CAA specifies three prerequisites for the listing of an air 

pollutant to be regulated by NAAQS. Specifically, this section provides that EPA:

[S]hall from time to time . . . list . . . each air pollutant –
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(A) emissions of which, in [the Administrator’s] judgment, cause 

or contribute to air pollution which may reasonably be anticipated

to endanger public health or welfare;

(B) the presence of which in the ambient air results from numerous 

or diverse mobile or stationary sources; and

(C) for which air quality criteria had not been issued before the 

date of enactment of the Clean Air Amendments of 1970, but for 

which [the Administrator] plans to issue air quality criteria under 

this section.

CAA § 108(a)(1).

Should EPA make final the Proposed Endangerment Finding, that finding would not be at 

all dispositive with regard to section 108. Section 108 and its companion provision, section 109, 

contain different language from that in section 202. Sections 108 and 109 of the CAA authorize 

listing of a pollutant as a criteria air pollutant, and regulation of that pollutant through NAAQS, 

for the purpose of addressing any endangerment of the public health or welfare that may 

reasonably be anticipated due to the quantities of the pollutant in the ambient air, which is the 

relatively limited portion of the atmosphere to which the general public has access. Id. § 

108(a)(2) (“Air quality criteria for an air pollutant [listed under section 108] shall accurately 

reflect the latest scientific knowledge useful in indicating the kind and extent of all identifiable 

effects on public health or welfare which may be expected from the presence of such pollutant in 

the ambient air, in varying quantities.”) (emphases added); id. § 109(b)(2) (secondary NAAQS 

for a section 108-listed air pollutant must be set at the level “requisite to protect the public 

welfare from any known or anticipated adverse effects associated with the presence of such air 

pollutant in the ambient air”) (emphasis added); 40 C.F.R. § 50.1(e) (“Ambient air means that 

portion of the atmosphere, external to buildings, to which the general public has access.”); Train
115

v. NRDC, 421 U.S. 60, 65 (1975) (“ambient air” is “the statute’s term for the outdoor air used by 

the general public”).

Even if EPA finalizes the Proposed Endangerment Finding, before the Agency could list 

any GHGs as criteria air pollutants under section 108 of the Act, it would have to examine and 

determine what, if any, effect on U.S. public health or welfare is caused by the presence of 

GHGs in the ambient air in the United States. The Proposed Endangerment Finding and the 

accompanying TSD do not address this matter, and it is far from clear, for example, that GHGs 

in the amount in which they are present in the ambient air in the United States could reasonably 

be anticipated to endanger public health or welfare. The lack of information regarding any

effects of GHGs on public health and welfare due to their presence in the U.S. ambient air could, 

in fact, be among a number of factors that would lead the Administrator to conclude that she has 

no “plans to issue air quality criteria” for GHGs -- the third prerequisite for listing under section 

108.

To use the third prerequisite in this (or any other) fashion, however, EPA might need to 

address whether and to what extent that prerequisite gives EPA discretion not to list a pollutant if 

the Agency has in fact made an affirmative endangerment finding for that pollutant. Although

EPA noted in the ANPR that the third prerequisite “could provide EPA discretion to decide 

whether to list those pollutants [i.e., GHGs] under section 108 for purposes of regulating them 

via the NAAQS,” 73 Fed. Reg. at 44477/2, in the 1970s, NRDC successfully argued to a federal 

district court in a CAA citizen suit that this language deprived EPA of any discretion to decline 

to list and regulate a pollutant under sections 108 and 109 where the Agency had conceded that 

the endangerment criterion (and section 108(a)(1)(B)’s “numerous or diverse mobile or 

stationary sources” criterion) was satisfied for that pollutant. That litigation culminated in the 
116

decision of the U.S. Court of Appeals for the Second Circuit in NRDC v. Train, 545 F.2d 320 (2d 

Cir. 1976), that EPA must list and regulate a pollutant under sections 108 and 109 when it has 

made an endangerment finding for that pollutant, notwithstanding the “plans to issue air quality 

criteria” provision in section 108(a)(1)(C). EPA correctly noted the existence of this case in the 

ANPR and suggested that, because it was decided before the Supreme Court’s decision in 

Chevron v. NRDC, 467 U.S. 837 (1984), the Agency may well have an argument that its original 

interpretation of the statute should now be accorded deference. 73 Fed. Reg. at 44477 n.229. In 

addition, the Second Circuit issued its decision before the development of case law, including 

case law in that circuit, on the narrowly circumscribed limits of citizen suit jurisdiction under the 

CAA and the scope of EPA “nondiscretionary duties” under the Act.63

The argument that the third criterion does not provide EPA with discretion regarding 

whether to list an air pollutant for which it has made an endangerment finding was advanced as 

recently as 2003, when three states (Connecticut, Maine, and Massachusetts) premised a citizen 

suit against the Administrator on the Second Circuit’s 1976 decision. Massachusetts v. Horinko, 

No. 3:03-CV-984 (D. Conn. filed June 4, 2003) (dismissed without prejudice by plaintiffs on 

September 3, 2003, in light of EPA’s denial of the rulemaking petition that led to Massachusetts 

v. EPA). More recently, national environmental group representatives have suggested that the 

“plans to issue air quality criteria” clause does give EPA discretion not to list and regulate, but 

they did not explain their legal rationale for abandoning the position advanced by NRDC and 

adopted by two courts over three decades ago. See, e.g., Strengths and Weaknesses of 

Regulating Greenhouse Gas Emissions Using Existing Clean Air Act Authorities: Hearing 

63 EPA’s discretion under section 108 extends not only to substantive determinations but also to 

the timing of any listing. CAA § 108(a)(1) (authorizing EPA, where the listing prerequisites are 

satisfied, to revise the list of criteria pollutants “from time to time”). 
117

Before the House Energy and Commerce Subcommittee on Energy and Air Quality, 110th Cong. 

(Apr. 10, 2008), Testimony of Lisa Heinzerling, Professor of Law, Georgetown University Law 

Center, at 6 (noting that the third prerequisite “may provide the Administrator somewhat more 

wiggle room in deciding whether to issue a NAAQS for a greenhouse gas, even after an 

endangerment finding”); Bookbinder Testimony at 9 (noting that the third prerequisite “appears 

to contemplate some discretion on EPA’s part in whether to establish a NAAQS”). UARG 

believes that, for many reasons, the argument for EPA discretion under section 108(a)(1)(C) is 

compelling, but in any event, EPA would need to state clearly and comprehensively its view of 

the matter -- specifically including its interpretation of the current effect of NRDC v. Train --

before it proceeds with any proposed rule that addresses, or that arguably could give rise to, 

regulation of GHGs under section 108 and 109.

X. A Final Endangerment Finding for GHGs Under Section 202(a) of the CAA Would 

Not Satisfy the Criteria Necessary To Take Any Action Under Section 115 of the 

Act.

Section 115 of the CAA authorizes the Administrator to require states to establish 

emission control requirements where the Administrator “has reason to believe that any air 

pollutant or pollutants emitted in the United States cause or contribute to air pollution which may 

reasonably be anticipated to endanger public health or welfare in a foreign country.” If EPA 

makes a final endangerment finding in the present proceeding, that finding would not satisfy the 

requirements of section 115. Before taking any steps to regulate under section 115, EPA would 

need to examine a wide range of issues, including not only issues concerning possible 

endangerment of public health or welfare in a specific foreign country but also whether the 

foreign nation in question gives the United States reciprocal rights (a prerequisite to any section 

115 regulation under section 115(c)) and whether required revisions to state implementation 

plans resulting from any EPA determination under section 115 would “prevent or eliminate the 
118

endangerment” (a criterion under section 115(b)). EPA also would have to show that it has 

“sufficient evidence correlating the endangerment to sources of pollution within a particular 

State,” a criterion that EPA and the courts have drawn from section 115. Her Majesty the Queen 

in Right of Ontario v. EPA, 912 F.2d 1525, 1533 (D.C. Cir. 1990).

XI. Conclusion

UARG appreciates the opportunity to submit these comments on the Proposed 

Endangerment Finding. For the reasons discussed above, EPA’s proposal is seriously flawed 

and does not provide a basis for the Agency to make an endangerment or “cause or contribute” 

finding with respect to GHGs under section 202(a)(1) of the CAA.
Attachment A
COMMENTS OF THE UTILITY AIR REGULATORY GROUP

on the

ADVANCE NOTICE OF PROPOSED RULEMAKING

REGARDING REGULATING GREENHOUSE GAS

EMISSIONS UNDER THE CLEAN AIR ACT

Docket ID No. EPA-HQ-OAR-2008-0318

HUNTON & WILLIAMS LLP

Norman W. Fichthorn

Allison D. Wood

James W. Rubin

Aaron M. Flynn

1900 K Street, N.W.

Washington, D.C. 20006

(202) 955-1500

Counsel for the Utility Air

Regulatory Group

November 28, 2008
ii

TABLE OF CONTENTS

I. Introduction and General Issues for EPA To Consider in Any Future Proposed 

Rulemaking on GHGs Under the CAA............................................................................ 2

II. UARG Agrees With the Concerns Expressed by Numerous Federal Agencies 

Regarding Possible Regulation of GHGs Under the CAA. ............................................ 10

III. In Any Future Proposed Rulemaking Regarding Regulation of GHGs Under the 

CAA, EPA Should Specifically Address the Special Needs and Perspectives of 

the Electric Generating Sector....................................................................................... 15

IV. Before EPA Could Present a Reasoned Basis for Any Future Proposed 

Endangerment Finding, the Agency Would Need To Address a Range of Issues 

Requiring Substantial Further Development.................................................................. 18

A. The Effect of Massachusetts v. EPA .................................................................. 19

B. The Endangerment Test..................................................................................... 22

1. The Legal Framework and Decision-Making Criteria............................. 22

2. Application of the Endangerment Test to the “Air Pollution” at 

Issue ...................................................................................................... 26

V. The Draft Endangerment TSD Does Not Provide a Sufficient Basis for Making 

Any Possible Future Endangerment Determination with Regard to GHGs Under 

the CAA........................................................................................................................ 33

A. The Draft Endangerment TSD Has Improperly Defined the Scope of 

Relevant GHG-Related Science, Rendering It Unfit for Use in Assessing 

Endangerment. .................................................................................................. 35

B. The Draft Endangerment TSD Relies on Scientific Information that Is 

Inadequate To Assess Whether Endangerment to U.S. Public Health or 

Welfare Exists. .................................................................................................. 39

C. The Draft Endangerment TSD Mischaracterizes the Conclusions of the 

IPCC on Which It Relies. .................................................................................. 44

D. Recent Individual Studies Undercut Conclusions Contained in EPA’s 

Draft Endangerment TSD and the Reports on Which It Relies. .......................... 50

E. Uncertainty Is Not Adequately Reflected in the TSD’s Analysis........................ 58

F. The Draft Endangerment TSD Contains Numerous Examples of Bias and 

Speculation that Are Inconsistent with the Scientific Evidence. ......................... 62
iii

G. The TSD’s Conclusions as to Climate Change-Related Effects on Specific 

Health and Welfare Resources Must Be Revised To Address the Scientific 

Flaws Identified in the Comments. .................................................................... 66

1. Human Health........................................................................................ 66

2. Air Quality............................................................................................. 68

3. Food Production and Agriculture ........................................................... 69

4. Forestry ................................................................................................. 71

5. Water Resources.................................................................................... 72

6. Sea Level Rise and Coastal Areas.......................................................... 73

7. Energy, Infrastructure, and Settlements.................................................. 74

8. Ecosystems and Wildlife........................................................................ 75

H. Conclusion ........................................................................................................ 76

VI. If EPA Decides To Propose Regulation of GHGs Under Any Existing Provision

of the CAA, EPA Will Need To Consider Numerous Issues Further.............................. 78

A. Issues Relating to Possible Regulation of Mobile Sources Under Title II of 

the CAA............................................................................................................ 79

1. Issues Raised in EPA’s Title II Discussion that May Implicate 

Potential Regulation of Non-Mobile Sources ......................................... 79

2. EPA’s Mobile Source Discussion Raises General Legal Issues That 

May Be Relevant to Other Potentially Regulated Sectors. ...................... 80

3. The Petitions Before EPA Raise Certain Issues that Are Relevant 

to the Utility Industry............................................................................. 82

B. Issues Relating to Possible Regulation Through NAAQS and SIPs (CAA 

§§ 107-110)....................................................................................................... 88

C. Issues Relating to Possible Regulation Through Performance Standards for 

New and Existing Stationary Sources (CAA § 111)........................................... 98

1. Authority To Regulate ........................................................................... 99

2. Efficacy ............................................................................................... 101

3. Policy Design Criteria.......................................................................... 102
iv

a. Effectiveness of Health and Environmental Risk Reduction...... 102

b. Certainty and Transparency of Results...................................... 103

c. Cost Effectiveness and Economic Efficiency............................ 103

d. Equity Considerations .............................................................. 103

e. Policy Flexibility Over Time .................................................... 104

f. Incentives for Innovation and Technology Development .......... 104

g. Pro-Competitiveness ................................................................ 104

h. Administrative Feasibility ........................................................ 105

i. Enforceability........................................................................... 105

j. Avoidance of Unintended Consequences.................................. 105

4. New and Existing Sources.................................................................... 106

5. Definition of Source Categories and Coverage of Sources.................... 107

6. Best Demonstrated Technology............................................................ 109

a. Technological Availability ....................................................... 109

b. Technological Availability in the Power Sector........................ 112

c. Carbon Capture and Sequestration............................................ 115

7. Market Mechanisms............................................................................. 118

8. Updating Information and Standards.................................................... 120

D. Issues Relating to Possible Regulation of GHGs as Hazardous Air 

Pollutants (CAA § 112)................................................................................... 120

E. Implications for the PSD Program from Possible Regulation of GHGs 

Under the CAA ............................................................................................... 123

F. Implications for the Title V Operating Permit Program Due to Possible 

Regulation of GHGs Under the CAA............................................................... 128

G. Title VI of the CAA, Which Addresses Stratospheric Ozone Protection, 

Does Not Provide EPA with Authority To Regulate GHGs.............................. 132

VII. Conclusion.................................................................................................................. 134
1

COMMENTS OF THE UTILITY AIR REGULATORY GROUP

on the

ADVANCE NOTICE OF PROPOSED RULEMAKING

REGARDING REGULATING GREENHOUSE GAS

EMISSIONS UNDER THE CLEAN AIR ACT

Docket ID No. EPA-HQ-OAR-2008-0318

November 28, 2008

______________________________________________________________________________

The Utility Air Regulatory Group (“UARG”) offers the following comments on the 

Advance Notice of Proposed Rulemaking Regarding Regulating Greenhouse Gas Emissions 

Under the Clean Air Act (“ANPR”), which the U.S. Environmental Protection Agency (“EPA” 

or “Agency”) published for public comment on July 30, 2008.

1 UARG is a voluntary, nonprofit 

group of electric generating companies and organizations and four national trade associations 

(the Edison Electric Institute, the National Rural Electric Cooperative Association, the American 

Public Power Association, and the National Mining Association). UARG’s purpose is to 

participate collectively on behalf of its members in EPA’s rulemakings and other proceedings 

under the Clean Air Act (“CAA” or “Act”) that affect the interests of electric generators and in 

litigation arising from those proceedings. UARG members would be significantly affected by 

any decisions EPA may make on issues raised in the ANPR concerning possible regulation of 

greenhouse gases (“GHGs”) under the existing provisions of the CAA. UARG appreciates the 

opportunity to comment on the ANPR and notes that the issues raised in the ANPR are critical to 

its members as well as to a broader group of industry parties, commercial interests, and the 

public.

1

73 Fed. Reg. 44354 (July 30, 2008).
2

I. Introduction and General Issues for EPA To Consider in Any Future Proposed 

Rulemaking on GHGs Under the CAA

At the outset, UARG recognizes that the issue of whether and how to regulate emissions 

of GHGs, including carbon dioxide (“CO2”), under the current provisions of the CAA is 

controversial and needs to be considered in the broadest context, given the dramatic impacts such 

regulation may have on other CAA regulatory programs and on the economy. As EPA 

Administrator Johnson himself accurately states in the preface to the ANPR, “[o]ne point is 

clear: [t]he potential regulation of greenhouse gases under any portion of the Clean Air Act 

could result in an unprecedented expansion of EPA authority that would have a profound effect 

on virtually every sector of the economy and touch every household in the land.” 73 Fed. Reg. at 

44355/1. UARG also underscores and agrees with Administrator Johnson’s assertion that the 

CAA is

ill-suited for the task of regulating global greenhouse gases. Based on the 

analysis to date, pursuing this course of action would inevitably result in a very 

complicated, time-consuming and, likely, convoluted set of regulations. These 

rules would largely pre-empt or overlay existing programs that help control 

greenhouse gas emissions and would be relatively ineffective at reducing 

greenhouse gas concentrations given the potentially damaging effect on jobs and 

the U.S. economy.

Id. at 44355/2-3.2

This concern is shared by the numerous federal agencies whose comments are appended 

to the ANPR. Indeed, most of the issues raised in the ANPR, including the scope of regulation 

2

Even the staff draft portion of the ANPR observes that “[i]n light of the CAA’s 

interconnections and other issues explored in this notice, EPA does not believe that all aspects of 

the Act are well designed for establishing the kind of comprehensive GHG regulatory program 

that could most efficiently achieve the GHG emission reductions that may be needed over the 

next several decades.” 73 Fed. Reg. at 44397/2-3. UARG does not believe that any of the 

current CAA provisions discussed in the ANPR provide an appropriate vehicle for GHG 

regulation, particularly of the electric power sector, for the many reasons stated below. 
3

and how to minimize and fairly allocate costs imposed by any regulatory program, are critical

issues for Congress to consider as its discussions on potential GHG regulation progress. UARG 

believes the best role that the ANPR can play is not in future regulation of GHG emissions under 

the “ill-suited” existing provisions of the CAA but in assisting Congress in considering a

possible legislative program to address climate change by providing necessary information on 

key aspects of any such program.3Indeed, the ANPR lists some of the most important principles 

for such legislation: (1) addressing GHG emissions in a manner that does not further harm the 

economy; (2) encouraging technological development; and (3) recognizing the threat of 

competitive disadvantage if other countries with significant emissions fail to control their 

emissions. Id. at 44397/1-2. The current CAA cannot adequately satisfy these three principles 

and thus is an inappropriate vehicle to address climate change meaningfully.

Curtailing economic costs is perhaps the most significant issue to consider in response to 

the ANPR. Since the ANPR was released in July 2008 in the midst of an already sluggish 

economy, the nation has faced a significant and worrisome economic downturn of uncertain 

duration. Most sectors of the economy are facing difficult financial and operating conditions. It 

is simply not appropriate to institute a regulatory program at this time that would impose even 

higher energy costs on American businesses and consumers. 

UARG fully understands and appreciates EPA’s efforts to “shape an overall approach for 

potentially addressing GHG emissions under the CAA as part of a broader set of actions to 

address GHG emissions taken by Congress, EPA, other federal departments and agencies, state 

3

The separate comments on the ANPR of the American Public Power Association, the Edison 

Electric Institute, and the National Rural Electric Cooperative Association, all of which are 

UARG members, explain the reasons for Congress to enact comprehensive legislation to address 

GHG emissions.
4

and local governments, the private sector, and the international community.” Id. at 44400/2.

UARG recognizes that the electric power sector plays an important role in national GHG 

emissions, but any regulation of that sector would need to be considered as part of a broader 

program that takes into account the full scope of national and international sources of GHG 

emissions, existing and soon-to-be-established state and regional programs, and the need to 

spread economic costs and regulatory burdens across a wide spectrum of sources. Any 

regulation of GHGs under the various provisions of the existing CAA must also recognize 

regulatory effects on other CAA programs, including the prevention of significant deterioration 

(“PSD”) and Title V programs, and how those effects would impact the electric power and other 

sectors. UARG therefore supports EPA’s decision to review the potential for GHG regulation as 

part of a set of broader domestic and international decisions and programs.

UARG also stresses that the Supreme Court’s decision in Massachusetts v. EPA, 127 S. 

Ct. 1438 (2007), does not mandate that EPA regulate GHGs under the CAA or do so within a 

specific period. EPA retains considerable discretion as to whether to make an endangerment 

finding under CAA § 202(a)(1), and if it does decide to make such a finding, the Agency has 

discretion over the timing of such a finding and when and how to take any subsequent regulatory

steps. In Massachusetts, the Supreme Court determined that the Act’s definition of “air 

pollutant” in section 302(g) encompasses “all airborne compounds of whatever stripe,” including 

GHGs. Id. at 1460. Having concluded that GHGs can be “air pollutants” under the CAA, 

however, the Court then explained that EPA has authority to regulate GHGs under CAA section 

202(a)(1) only “[i]f EPA makes a finding of endangerment” under that provision. Id. at 1462. 

Although the Court rejected the specific rationale offered by EPA for denying a petition to 

regulate GHGs from new motor vehicles as unrelated to the scope of the relevant statutory text, it 
5

emphasized the limited nature of its decision: “We need not and do not reach the question 

whether on remand EPA must make an endangerment finding, or whether policy concerns can 

inform EPA’s actions in the event that it makes such a finding.” Id. at 1463. Rather, discretion 

remains with the Agency regarding whether and how to make a determination as to 

endangerment, as long as EPA provides a “reasoned justification” for its decision and its 

“reasons for action or inaction” are “grounded . . . in the statute.” Id. Moreover, the Court

recognized that even if EPA does make an affirmative endangerment finding, it would “no doubt 

[have] significant latitude as to the manner, timing, [and] content” of its regulations and 

“coordination of [those] regulations with those of other agencies.” Id. at 1462.

Thus, the Agency maintains considerable discretion as to whether to make an 

endangerment finding under section 202(a)(1).4Even if EPA were to find endangerment, it 

would retain discretion to determine when and how to regulate. Moreover, the regulatory

authority reviewed by the Supreme Court pertains only to new motor vehicles and engines under 

Title II. Nothing in Massachusetts establishes any requirements for regulating stationary sources 

of GHGs. Therefore, EPA is under no legal obligation to regulate GHGs from stationary sources 

as a result of the Supreme Court’s decision, and can -- and should -- take time to consider

carefully whether to do so in the context of the many legal and policy issues raised by the ANPR 

and by the comments of UARG and other parties on the ANPR.

Overall, UARG believes that the many issues set forth in the ANPR, on balance,

demonstrate the problems inherent in any attempt to regulate GHGs under the existing provisions 

of the CAA and in analyzing the economic effects of such regulation. UARG believes that EPA 

4

The Agency is also under no obligation to make an endangerment finding under section 

202(a)(1) by a date certain. See Massachusetts v. EPA, No. 03-1361 (D.C. Cir. June 26, 2008) 

(denying petition for writ of mandamus).
6

understates the problems when it says in the ANPR that the “large temporal and spatial scales of 

the climate change challenge introduce regulatory issues beyond those typically presented for 

most traditional air pollutants.” 73 Fed. Reg. at 44401/2. The unique characteristics of this 

challenge (e.g., longer atmospheric lifetimes of the gases, uniform mixing of the gases in the 

global atmosphere, and cumulative impacts from past, present, and future emissions) create 

many uncertainties over long time frames and across national boundaries, thereby increasing the 

complexity of any attempt to design an effective and comprehensive long-term regulatory

strategy. Id. at 44400-01. Further, these characteristics make GHGs a poor fit, at best, for the 

statutory endangerment tests in several of the CAA provisions discussed in the ANPR, which 

were enacted to address conventional pollutants and their localized, specific, and direct public 

health and welfare impacts. 

The data reported by EPA for emissions per sector show that GHG emissions in the 

United States are spread out over a number of sectors. Even within one sector, there may be a 

diversity of types and sizes of sources. If EPA should decide to regulate GHGs under the 

existing provisions of the CAA, it would have to consider carefully how to allocate the burden 

and costs of such regulation fairly among and within these sectors, as well as to account for the 

significant global emissions that will occur notwithstanding the imposition of any CAA 

regulatory requirements.

The development of new technologies will be key to the ability to reduce GHG emissions 

from all sectors of the economy. But while there may be existing technologies that can be 

employed in the short term as identified in the ANPR, such as improved plant efficiencies, fuel 

switching, nuclear power, and renewable power, each of these technologies currently faces 

obstacles to widespread deployment or limits to the impact it may have. The ANPR’s discussion 
7

of these technologies is quite generalized, so it is difficult to comment more specifically on how 

EPA could or would require implementation of these technologies through the existing CAA. In 

any future proposed rulemaking on GHG regulation, EPA would need to analyze why such 

technologies are not already widely being used to reduce GHG emissions in the relevant sectors 

and whether regulation through existing CAA provisions would overcome obstacles to their 

implementation.

As to possible future technologies, EPA has not provided an adequate basis on which the 

public may comment meaningfully on how they could be applied under existing CAA 

provisions. As will be described later, the current CAA tends to constrain the use of unproven or 

speculative technologies, so the existing Act may not be useful for achieving the technological 

innovations that may be necessary for significant GHG reductions. Section VI.C. of these 

comments provides more detailed information on technologies for electric generating plants and 

carbon capture and sequestration (“CCS”).

5 UARG supports appropriate federal efforts to fund 

the development and deployment of technology necessary to reduce GHG emissions. 

As will be discussed in more detail in section VI.C., EPA should be mindful that controls 

needed to reduce emissions of conventional pollutants, such as sulfur dioxide (“SO2”) and 

nitrogen oxides (“NOx”), and new control technologies such as CCS can require large amounts 

of energy and decrease plant efficiencies, leading to increased GHG emissions. Moreover, EPA 

should consider to what extent improvements in existing plants to increase efficiencies and 

reduce GHG emissions may implicate New Source Review (“NSR”) concerns. 

A meaningful discussion of the effects of possible GHG control programs on non-air 

environmental media must await a more specific description of such programs. Nevertheless, 

5 CCS is also commonly referred to as carbon capture and storage.
8

EPA correctly observes in the ANPR (73 Fed. Reg. at 44407-08) that certain types of potential 

programs and technologies may have effects on other environmental media -- as well as on the 

cost to implement, and the ability to comply with, statutory and regulatory requirements 

governing those other media. Thus, for example, the potential use of CCS technology raises a 

number of issues that currently are being considered in the context of a proposed rulemaking 

under the Safe Drinking Water Act’s Underground Injection Control program. See 73 Fed. Reg. 

43492 (July 25, 2008). Similarly, other possible future or emerging emission reduction 

technologies may implicate issues concerning water use and availability (particularly for 

facilities in arid areas) and waste disposal. EPA should carefully consider impacts on other 

media -- and on compliance with other environmental laws and regulations -- if it develops a 

proposed rule for GHG emission control requirements under existing provisions of the CAA.

UARG agrees that the policy and economic considerations set forth in the ANPR (73 

Fed. Reg. at 44409) are among those EPA should strongly consider in determining whether GHG 

regulation is appropriate and warranted under existing CAA provisions. As to market-oriented 

approaches under the CAA (id. at 44409-12), EPA discusses several options in the ANPR with 

regard to instituting cap-and-trade and other market-based mechanisms under the Act’s existing 

provisions.6In general, however, if EPA were to promulgate both source-specific or sectorbased “command and control” programs (e.g., PSD) and market-based programs, any cost 

savings from market-based programs could be greatly reduced or eliminated by countervailing 

additional costs to satisfy the command-and-control requirements. Id. at 44411-12.

6

EPA correctly notes that, should it decide to establish a carbon tax or fee (or a provision that 

approximates a tax or fee) for any category or categories of sources, it would need to consider 

whether it has authority to do so under the relevant provisions of the CAA. 73 Fed. Reg. at 

44411/1-2.
9

As to the choice between economy-wide and sector-based regulatory approaches (id. at 

44411-13), UARG strongly believes that any regulatory program should cover the broadest 

spectrum of sources and not single out any one sector simply because more information about 

that sector is available. In general, should EPA decide to propose regulations to control GHG 

emissions under the CAA, it should do so through programs that lower the costs of emission 

controls and spread those costs fairly across all contributing sources and sectors, while also 

recognizing the limits of such programs. These limits include the legal and practical limitations 

imposed by the CAA itself and the past (and continuing) opposition to such programs by 

environmental organizations and some states.

EPA raises a number of other program design issues very generically. These are 

important to consider in any proposed regulatory program, such as the reasons to differentiate 

between new and existing sources (which generally have shorter useful lives and require more 

costly retrofits), emissions leakage, and international competitiveness. Id. at 44413-14. Those 

issues are discussed, where relevant, in later sections of these comments in regard to specific 

CAA sections. 

EPA identifies several overarching analytical challenges for economic analysis of any 

potential GHG regulation under existing CAA provisions, including long time horizons and the 

need to analyze costs and benefits over those horizons; the uncertainty inherent in those analyses; 

international considerations; how to value domestic and international marginal benefits; 

estimating energy security benefits; how to assess interactions with other, non-climate policies 

such as reduction of traditional air pollutants; and integrating economic and non-economic 

considerations. Id. at 44414-16. UARG agrees that these are all key issues that further

demonstrate the complexity of any attempt to adapt and apply CAA-based analyses developed 
10

for conventional pollutants to an entirely new and different type of emissions. EPA should 

ensure that its policy choices associated with any GHG emission controls that it may propose are 

informed by and address these analytical challenges as well as other important policy, legal, and 

ethical questions. See id. at 44417/1-2. The CAA, as it currently exists, with provisions 

intended to address conventional pollutants in far less complex scenarios, simply does not 

provide the most appropriate context for undertaking this challenge.7

II. UARG Agrees With the Concerns Expressed by Numerous Federal Agencies 

Regarding Possible Regulation of GHGs Under the CAA.

UARG believes it is very significant and telling that the main federal agencies and 

Executive Branch offices with expertise in scientific, environmental, economic, and commercial 

matters -- the Office of Information and Regulatory Affairs (“OIRA”), which is part of the Office 

of Management and Budget (“OMB”); the Council of Economic Advisers (“CEA”); the Office 

of Science Technology and Policy (“OSTP”); the Council on Environmental Quality (“CEQ”); 

the Department of Agriculture (“USDA”); the Department of Commerce (“Commerce”); the 

Department of Transportation (“DOT”); the Department of Energy (“DOE”); and the Office of 

Advocacy, Small Business Administration (“SBA”) -- so strongly disagree with the ANPR that 

their comments were appended in whole to the document. This is not simply a matter, as some 

7

EPA further recognizes that determining an acceptable level of climate change involves 

important value judgments and acknowledges that “[i]t is not the purpose of this ANPR to make 

any judgment regarding what an appropriate stabilization goal may be.” Id. at 44401/2. But if 

EPA were to decide to propose to regulate GHG emissions under existing provisions of the 

CAA, it would have to make such judgments to balance costs and benefits, determine the goals 

of any proposed regulations, and assess the effectiveness of any proposed regulations in meeting 

these goals. For example, how stringent would GHG reductions or limitations need to be on a 

sectoral or national level in response to any endangerment determination? How would EPA 

determine an appropriate reduction goal or limitation for a sector or group of sectors, given the 

past, present, future, and international contributions to climate change, and the inability to 

attribute specific risks to global concentrations? These and other issues make developing any 

proposed CAA regulatory approaches a particular challenge. 
11

may claim, of the Bush Administration’s disinclination to establish GHG regulations under the 

existing CAA. Rather, it shows that there is fundamental disagreement by the most relevant 

federal agencies that GHG regulation under existing CAA provisions is prudent, practical, or

even fully authorized. UARG agrees with the salient concerns of these agencies and with the 

central principles underlying those concerns, including:

· The ill-suited nature of the CAA for GHG regulation, particularly given the complexity 

of the issues involved in any such regulation. This concern is universally shared by the 

commenting agencies as well as Administrator Johnson. Id. at 44359. For example, 

Administrator Dudley of OIRA calls the ANPR a “deeply flawed and unsuitable vehicle for 

reducing greenhouse gas emissions.” Id. at 44356.

· Impacts that regulation of CO2 may have on a wide range of CAA programs, 

particularly the PSD and Title V programs. EPA correctly identifies the concern that any 

regulation of GHGs under one part of the CAA may affect other parts and require regulation 

of many new sources through these programs. That concern is shared collectively by the 

commenting agencies, which recognize the tremendous burdens that such regulation would 

place on U.S. businesses and the public. In this regard, DOE observes that regulation of 

GHGs would significantly increase the costs associated with the operation of power plants 

and industrial sources, as well as the direct energy use for commercial and residential users, 

including many sources of GHGs not currently regulated. Id. at 44366/2. CEQ states that 

EPA should conduct “a much more complete technical, institutional, and economic analysis 

of the far reaching consequences that will arise from the automatic application of existing 

regulations that would occur in the event EPA makes an endangerment finding” and 

subsequently regulates CO2. Id. at 44388. 
12

· Economic costs and burdens of a regulatory program and the degree to which such 

regulation would intrude into the operations and activities of sources, many of which 

were previously unregulated. Commerce focuses on the costs that CAA regulation of 

GHGs would impose on workers, consumers, and producers, including the high costs of 

compliance with multiple state regulations, reliance on technologies that are not yet viable, 

and the impacts on a large number of small businesses and nonprofit organizations that have

not been regulated under the CAA as sources in the past but now would be subject to costly, 

lengthy PSD and Title V permitting procedures. Id. at 44371-76. SBA also expresses 

serious concerns with the negative impacts such regulation would have on small entities by 

subjecting large numbers of firms to costly and burdensome new requirements. Id. at 44390-

96. CEA and OSTP similarly warn that regulation would be inordinately burdensome, 

especially for previously unregulated small sources. Id. at 44383. See infra at sections VI.E. 

and VI.F.

· The lack of state, regional, or national environmental benefits, and concerns about

harm to U.S. industry competitiveness. CEA and OSTP warn that CAA regulation would 

create cumbersome sets of rules and restrictions that would be excessive and disproportionate 

at the state and facility levels and might not even meet the purported environmental goals. In 

particular, CEA and OSTP note that health and welfare impacts cannot be quantified to the 

standards required by the CAA and that no credible framework exists to give assurance that a 

target can be met. Id. at 44380-84. Commerce also identifies problems in labor cost and 

competition issues, id. at 44371-76, and CEQ states that leakage and global emissions may 

offset any benefits the U.S. might otherwise obtain from reductions under CAA regulation, 

id. at 44385-89.
13

· Perceived weaknesses and uncertainties in the legal analysis of regulatory options.

OIRA expresses concern about EPA’s “untested legal propositions” for purported “flexible” 

interpretations of the CAA and “untested legal theories” to suggest that some CAA 

provisions could be adapted to provide economic incentives to reduce GHGs (e.g.,

establishing a nationwide cap-and-trade program). Id. at 44357-58. Collectively, USDA, 

Commerce, DOT, and DOE note that EPA’s theories are uncertain and subject to challenge. 

Id. at 44360. Indeed, although EPA asserts authority to regulate GHGs under a wide scope 

of provisions of the Act, it then seeks comment on whether it in fact has such authority when 

it specifically discusses those provisions in the ANPR.

· Disagreements over assumptions as to costs of technologies and availability of those

technologies to control and reduce emissions. Whether regulatory controls on GHGs will 

be effective and affordable depends to a great extent on availability of suitable technologies

to achieve those controls, but it is not at all clear that the ANPR’s review of technology is 

realistic in all situations. OIRA warns that the ANPR “could result in the piecemeal 

application of command-and-control regulation -- based on EPA staff determinations of the 

availability and suitability of a wide range of technology -- covering both U.S. manufacturing 

activity and a broad range of commercial and household activities to an extent well beyond 

the scope of current regulation.” Id. at 44357. Commerce reiterates that regulation would be 

costly if it relies on technologies that are not viable. Id. at 44371-76.

· Duplication of existing laws and regulatory programs. CEA and OSTP, as well as the 

other commenting agencies, express their concerns that GHG regulation under the CAA 

would, to a significant extent, duplicate existing programs and authorities, especially 

concerning mobile sources and fuel economy. Id. at 44361-64, 44383. CEQ believes more 
14

generally that the ANPR ignores how new regulations would duplicate or contradict 

numerous mandates, incentives, partnerships, and federal and state legislation, as well as 

some of EPA’s own programs, including mandates under the Energy Independence and 

Security Act of 2007 (“EISA”), Pub. L. No. 110-140, 121 Stat. 1492 (2007), actions taken 

under the Montreal Protocol such as accelerated phase-out of hydrochlorofluorocarbons, state 

renewable portfolio standards, programs under the Energy Policy Act of 2005, and DOE and 

EPA voluntary GHG emission reduction partnerships. 73 Fed. Reg. at 44386-87.

The Chair of the CEQ best sums up many of the collective concerns of the commenting 

agencies8 when he states that the ANPR

does not provide a full and meaningful discussion of the broader policy and 

economic context in which it is considering, in the event of an endangerment 

finding, triggering the prospect of essentially automatic and immediate regulation 

over a vast range of community and business activity and an equally vast range of 

potential discretionary regulations with respect to the same and additional

activities.

Id. at 44385. EPA should not propose any finding of endangerment or any regulation under the 

existing CAA without providing such a discussion and a comprehensive analysis of the many 

significant economic, technical, institutional, environmental, scientific, regulatory, legal, and 

policy issues that would be implicated by such regulation. See id. at 44388. 

8

In addition to the regulatory, legal, and policy concerns raised by these agencies, OSTP raises a 

number of important issues concerning the significant complexities and uncertainties associated 

with anthropogenic climate change that distinguish GHGs from traditionally regulated pollutants 

and increase the technical difficulty of any regulation of those gases under the existing 

provisions of the CAA. 73 Fed. Reg. at 44379-81. CEQ comments that EPA should take 

additional comment on OSTP’s remarks and observations as to the current and future capability 

of science with respect to predictions and projections on a national, regional, and local scale. Id.

at 44387. UARG agrees that EPA must carefully consider these issues.
15

III. In Any Future Proposed Rulemaking Regarding Regulation of GHGs Under the 

CAA, EPA Should Specifically Address the Special Needs and Perspectives of the 

Electric Generating Sector.

UARG agrees with the comment of DOE that the ANPR shows little understanding of 

how GHG emissions regulation under existing CAA provisions would affect U.S. energy

security and economic security needs. These important matters are barely noted in the ANPR. 

Id. at 44371. These concerns are particularly acute for the electric generating industry for a 

number of reasons, and EPA should take the sector’s special perspectives into account as the 

Agency determines whether and how to propose regulation of GHGs under the current 

provisions of the CAA.

First, the sector may be seen as a particularly tempting target for GHG regulation because 

more is known about electric generating facilities’ emissions and emission controls than about 

emissions from and emission controls at many other industries. This is because utilities report 

their CO2 emissions to EPA, these facilities are already subject to strict emission controls and 

standards for conventional pollutants, and much of the public attention has focused on reducing 

GHG emissions from this sector. Hence, all of the concerns identified above by the commenting 

federal agencies are magnified for the electric generating sector to the extent that sector is at risk 

of bearing a disproportionate and unfair burden under a GHG regulatory program. 

There are many sources of GHGs in the United States. According to the ANPR, the 

electric power sector was responsible for 33.7% of all U.S. GHG emissions in 2006, while the 

transportation sector emitted 28%. The remaining U.S. GHG emissions in 2006 came from the 

industrial sector (19%), the residential and commercial sectors (4.8% and 5.6% respectively),

and the agriculture sector (6.4%). Id. at 44402-03. Thus, although the electric power sector is a 

significant source of U.S. GHG emissions, it is far from being the only source, and any CAA 

regulations must take into account the other sectors and allocate the burden of regulation
16

appropriately. Moreover, concern about climate change arises from global concentrations of 

GHG emissions, caused by global emissions. Any CAA regulation must reflect the fact that U.S. 

emissions, while a significant source of GHG emissions worldwide, are not the only large

contributor.

9

Even if U.S. emissions were reduced significantly, GHG concentrations would 

continue to grow on a global basis. The U.S. electric power sector should not shoulder a 

disproportionate burden in addressing GHG emissions when significant emissions also occur

from other domestic sources and other countries.

Further, the electric power sector itself is made up of diverse types of sources, and any 

regulatory program must take into account their differences -- and the difference in control 

technologies that may be available to them. In addition, as stated infra in section VI.C., CCS 

technology is far from being commercially available for power plants. If EPA decides to 

regulate GHGs under the CAA, increasing efficiencies may be the only -- albeit limited --

achievable method in the short term of reducing GHG emissions at existing and new plants, and 

cost-effective applications differ based on the age and size of the plant. 

A critical issue for EPA to consider is the reliability of the electric power grid. The North 

American Electric Reliability Corporation (“NERC”), which has regulatory authority over the 

operations of the electricity grid under federal law, has expressed serious concerns about the 

effect regulation of GHGs may have on electricity reliability in the United States. In a recent 

report, NERC identified several key reliability issues associated with climate change issues that 

EPA should consider in any future regulation of GHGs under the CAA. NERC, Special Report: 

9

For example, GHG emissions from China now exceed U.S. GHG emissions. International 

Energy Agency, CO2 Emissions from Fuel Combustion 1971-2005 (2007). The Netherlands 

Environmental Assessment Agency was the first organization to conclude that Chinese GHG 

emissions exceeded U.S. emissions in 2006. See http://www.mnp.nl/en/dossiers/Climatechange/ 

moreinfo/Chinanowno1inCO2emissionsUSAinsecondposition.html.
17

Electric Industry Concerns on the Reliability Impacts of Climate Change Initiatives (Nov. 2008) 

(“NERC Special Report”), available at http://www.nerc.com/files/2008-Climate-InitiativesReport.pdf. Rick Sergel, President and CEO of NERC, commented that:

We are concerned that, when viewed from a continent-wide perspective, current 

climate initiatives do not adequately address key reliability objectives, particularly 

the need for a strong and robust transmission system. . . . As we consider our 

energy future, it becomes increasingly clear that our success in reducing carbon 

emissions and realizing energy independence will hinge on our ability to provide 

reliable, clean . . . electricity where and when it is needed.

Press Release, NERC, Climate Policy Critical to Grid Reliability (Nov. 10, 2008), available at

http://www.nerc.com/news_pr.php?npr=198.

In particular, the NERC Special Report noted that broad-scale fuel switching from coal to 

natural gas in response to GHG regulation would jeopardize electric reliability. Retirements of 

coal-fired power plants over a short timeline in response to GHG regulation could result in the 

loss of generation needed to support the integrity of the bulk power system and thus severely 

harm reliability, especially in those regions that depend heavily on coal for fuel. Also, the broadscale replacement and relocation of generating plants from current coal sites to sites that would 

be suitable for new or expanded natural gas-fired generation would require significant upgrades 

to existing transmission infrastructure. NERC Special Report at 6-10. NERC notes that “[t]he 

timelines established for CO2 reductions will be one of the driving factors determining the extent 

to which this fuel-switching occurs and any resulting impacts to reliability.” Id. at 6.

Another important consideration is that existing transmission infrastructure is insufficient 

to deliver electricity from new “cleaner” sources of power to the grid. The existing electricity 

transmission network cannot reliably deliver power from new sources of renewable power to 

demand centers. As states attempt to deliver “clean energy” over already heavily-loaded 

transmission lines to meet renewable portfolio standard requirements, the transmission system 
18

will need to be expanded to meet these new requirements. Id. at 11-14. As NERC notes, “[t]he 

ability to reduce the carbon emissions of the electric sector hinges on having a robust 

transmission system,” and the “[e]xisting transmission infrastructure is inadequate to reliably 

integrate new renewable sources to demand centers.” Id. at 11.

Because of the vital importance of electric reliability to national security and to the nation

generally, EPA needs to consider carefully how any proposed regulation of GHGs under the 

CAA may affect the reliability of the electricity generation, transmission, and distribution system 

in this country.

IV. Before EPA Could Present a Reasoned Basis for Any Future Proposed 

Endangerment Finding, the Agency Would Need To Address a Range of Issues 

Requiring Substantial Further Development.

Section V of the ANPR summarizes EPA’s “work to date on an endangerment analysis in 

response to the Supreme Court’s decision in Massachusetts v. EPA.” 73 Fed. Reg. at 44421/2. 

This section includes three main parts: (1) a fairly brief description of what EPA views as the 

legal framework for an endangerment determination; (2) a summary of information and issues 

bearing on such a determination; and (3) a discussion of how EPA might determine whether 

emissions of GHGs from motor vehicles or fuels cause or contribute to air pollution that may 

reasonably be anticipated to endanger public health or welfare. As discussed below, this section 

of the ANPR raises a range of issues that require substantial further development before EPA 

could present a reasoned basis for any proposed endangerment finding. 

Before EPA could make and publish a final endangerment finding that could be the basis 

for regulation, EPA would have to provide public notice of -- and solicit, consider, and respond 

to public comment on -- a specific proposed endangerment finding. See Thomas v. New York, 

802 F.2d 1443, 1447 (D.C. Cir. 1986); Nat’l Asphalt Pavement Ass’n v. Train, 539 F.2d 775, 779 

n.2 (D.C. Cir. 1976). The ANPR of course does not provide public notice of any proposed 
19

endangerment finding. The following comments provide UARG’s views on the issues that EPA 

would have to address before it could provide effective public notice of any determination that 

emissions of GHGs from new U.S. motor vehicles (or any other sources) under the Act cause or 

contribute to air pollution that may reasonably be anticipated to endanger public health or 

welfare. 

A. The Effect of Massachusetts v. EPA

Scattered passages in the ANPR provide only a limited discussion of the Supreme 

Court’s decision in Massachusetts v. EPA. See id. at 44398/1-2, 44418/3, 44421/2. Some 

aspects of this discussion appear to be incomplete and internally inconsistent. For example, the 

ANPR at one point states that “[t]he Supreme Court’s decision in Massachusetts v. EPA requires 

EPA to address whether GHG emissions from new motor vehicles meet the endangerment test of 

CAA section 202(a)(1).” Id. at 44418/3. This statement could be read as suggesting that EPA 

believes it has an obligation to determine whether or not that endangerment test is met. 

Elsewhere in the ANPR, EPA recognizes that scientific uncertainty is a legitimate factor in 

determining how to respond to the petition for rulemaking and may “‘preclude[] EPA from 

making a reasoned judgment as to whether greenhouse gases contribute to global warming.’” Id.

at 44398/1 (quoting Massachusetts, 127 S. Ct. at 1463); see also id. at 44421/2. Yet the ANPR 

fails to explain that the references in the Court’s opinion to “contribution to global warming” are 

a shorthand reference to the statutory test of contribution to air pollution that may reasonably be 

anticipated to endanger public health or welfare. See, e.g., Strengths and Weaknesses of 

Regulating Greenhouse Gas Emissions Using Existing Clean Air Act Authorities: Hearing 

Before the House Energy and Commerce Subcommittee on Energy and Air Quality, 110th Cong. 

(Apr. 10, 2008), Testimony of Robert J. Meyers, Principal Deputy Assistant Administrator for 
20

Air and Radiation, EPA, at 3 (characterizing the Court’s reference to scientific uncertainty as 

relevant to “making a reasoned judgment on such an endangerment determination”). 

Moreover, although the ANPR observes that the Court did not “dictat[e] EPA’s action on 

remand” or “decid[e] whether EPA must find there is endangerment,” 73 Fed. Reg. at 44398/2, 

the ANPR provides no clear description of the limited nature of the Court’s holding -- that, for 

example, EPA on remand need not make any finding regarding endangerment10 and need not 

confine its consideration of factors to scientific uncertainty as long as those factors relate to the 

language of the statute. The Court found EPA’s decision to deny the rulemaking petition to be 

arbitrary because its explanation for its denial “rest[ed] on reasoning divorced from the statutory 

text,” 127 S. Ct. at 1462, and was unsupported by “reasoned explanation” that is “ground[ed] . . .

in the statute,” id. at 1463. Section 202(a)(1), the Court held, “condition[s] the exercise of 

EPA’s authority on its formation of a ‘judgment,’” and “that judgment must relate to whether an 

air pollutant ‘cause[s], or contribute[s] to, air pollution which may reasonably be anticipated to 

endanger public health or welfare.’” Id. at 1462 (quoting CAA § 202(a)(1)). Thus, under the 

Court’s opinion, EPA’s responsibility is to make a judgment, in response to the rulemaking 

petition, that does not “ignore” the text of section 202(a)(1), that “exercise[s] discretion within 

defined statutory limits,” id., and that is supported by a “reasoned explanation,” id. at 1463.

Furthermore, certain statements in the ANPR’s limited discussion of Massachusetts do 

not fully or consistently reflect the Court’s description of EPA’s authority. For example, one 

part of the ANPR says, without any apparent qualification, that “[i]f the Administrator makes a 

positive endangerment determination for GHG emissions from new motor vehicles, he must 

10 See 127 S. Ct. at 1463 (“We need not and do not reach the question whether on remand EPA 

must make an endangerment finding. . . .”).
21

regulate those GHG emissions under section 202(a).” 73 Fed. Reg. at 44418/3. Yet a separate 

passage acknowledges the Court’s statement that its holding does not address whether EPA on 

remand may take into account “policy concerns” that might “inform EPA’s actions in the event 

that it makes such a finding.” 127 S. Ct. at 1463, quoted in 73 Fed. Reg. at 44398/2. And, as 

that passage also notes, the Court made clear that EPA “has significant latitude as to the manner, 

timing, [and] content” of any regulations that it does adopt “and coordination of [those] 

regulations with those of other agencies.” 127 S. Ct. at 1462, quoted in 73 Fed. Reg. at 44398/2. 

Thus, to the extent EPA proceeds with a notice of proposed rulemaking, it will be essential for it 

to provide the public with a discussion of Massachusetts that reflects in a consistent way (1) the 

limited nature of the Court’s holding11 and (2) the Court’s recognition of EPA’s substantial 

discretion as to (a) the timing and manner of any regulations that may accompany or follow an 

affirmative endangerment finding and (b) coordination of its regulatory determinations and 

actions with those of other agencies, such as the Department of Transportation -- as to which, the 

Court noted, EPA is to seek to “avoid inconsistency” in implementing statutory obligations. 127 

S. Ct. at 1462.

In addition, in developing any such notice, EPA should relate the holdings in 

Massachusetts to the specific issues EPA would have to engage before it could propose an 

endangerment finding with respect to GHG emissions from new U.S. motor vehicles (or other 

sources). Some of these issues are discussed below. 

11 For example, EPA in any notice of proposed rulemaking should explain its view of what 

would constitute a “reasonable explanation as to why it cannot or will not exercise its discretion” 

to determine whether new U.S. motor vehicle emissions meet the endangerment standard. 127 S. 

Ct. at 1462.
22

B. The Endangerment Test

1. The Legal Framework and Decision-Making Criteria

Nothing in section 202(a)(1) (or any other provision of the Act) refers to, or suggests 

EPA may treat, global climate change as endangerment per se, apart from specifically

identifiable physical effects on public health or welfare in the United States that may result from 

emissions of GHGs in the amounts in which they occur from new U.S. motor vehicles (or any

other relevant source category). Thus, the relevant issues for EPA’s exercise of judgment under 

section 202(a)(1) include whether emissions from new U.S. motor vehicles of the GHGs 

identified in the petition for rulemaking “cause[], or contribute[] to, air pollution which may 

reasonably be anticipated to endanger public health or welfare” and whether existing scientific 

information is “sufficient” to allow EPA to come to a conclusion on that question. Id. at 1462-

63. As noted above, EPA has discretion to exercise its judgment on remand consistent with the 

statutory criteria, and the Court did not prejudge the outcome of EPA’s consideration of the 

section 202(a)(1) endangerment criterion.

The ANPR describes what it characterizes as the two-part nature of the endangerment 

test: “First, the Administrator must decide if, in his judgment, air pollution may reasonably be 

anticipated to endanger public health or welfare. Second, the Administrator must decide 

whether, in his judgment, emissions of any air pollutant from new motor vehicles or engines 

cause or contribute to this air pollution.” 73 Fed. Reg. at 44421/3. The ANPR then discusses 

the legislative history of the endangerment criterion in section 202(a)(1) and similar criteria in 

other parts of the Act, and in particular the legislative history of the 1977 amendments to the Act, 

which in part reflected the D.C. Circuit’s decision in Ethyl Corp. v. EPA, 541 F.2d 1 (D.C. Cir. 

1976). Id. at 44422/2-3. EPA observes that the court in that case was confronted with an 

argument that EPA’s regulation of lead in gasoline under section 211 of the Act was inconsistent 
23

with the statutory standard in effect at that time, which established a “will endanger” test for 

regulation under that section. Rejecting an industry challenge to the regulation, the court held, 

among other things, that section 211 did not require proof of actual harm as a prerequisite to 

regulation and that Congress intended the statute to be preventative or precautionary in nature. 

In addition, it indicated that EPA has authority to consider the cumulative effects of exposure to 

lead from numerous sources, not only lead from the motor vehicle fuels being considered for 

regulation. 

The ANPR also notes that the legislative history of the 1977 amendments reflected the 

view that the statute’s call for the Administrator to exercise “judgment” in applying the 

endangerment test pertains both to the “cause or contribute” analysis and to the “may reasonably 

be anticipated to endanger” language. And that legislative history makes clear that EPA’s 

“projections, assessments and estimates must be reasonable, and cannot be based on a ‘crystal 

ball inquiry.’” Id. at 44422/3. The legislative history thus reflects congressional intent to use the 

statutory phrase “may reasonably be anticipated” to “build[] upon the precautionary and 

preventative goals already provided in the use of the term ‘endanger.’” Id. EPA adds that, based 

on the legislative history:

[T]he phrase “cause or contribute” ensures that all sources of the contaminant 

which contribute to air pollution be considered in the endangerment analysis (e.g., 

not a single source or category of sources). It is also intended to require the 

Administrator to consider all sources of exposure to a pollutant (e.g., food, water, 

air) when determining risk.

Id. 

The ANPR notes that the legislative history does not fully explain what EPA should 

consider when making an endangerment finding:

[I]t is not clear ... what constitutes a sufficient “contribution” for purposes of 

making a finding. The CAA does not define the concept “cause or contribute” 

and instead requires that the Administrator exercise his judgment when 
24

determining whether emissions of air pollutants cause or contribute to air 

pollution. As a result, the Administrator has the discretion to interpret “cause or 

contribute” in a reasonable manner when applying it to the circumstances before 

him.

Id. EPA points out, however, that in Ethyl, the court observed that, even where EPA takes into 

account “cumulative impact,” “‘emissions must make more than a minimal contribution to total

exposure in order to justify regulation.’” Id. at 44423/2 (citing Ethyl, 541 F.2d at 31 n.62).

Although EPA is correct that it has some discretion in applying the endangerment test, it 

will be important for the Agency, in any notice of proposed rulemaking, to provide its proposed 

interpretation of how that test should be construed in the context of the specific source categories 

being considered for regulation. For example, with respect to the “contribution” question, EPA 

must address specifically how it will determine whether emissions of one or more GHGs 

considered individually -- or, alternatively, various possible combinations of GHGs -- from 

motor vehicles and motor vehicle fuels can properly be determined to “cause or contribute” to 

“air pollution.” Id. at 44428/1-3. EPA must also discuss how it will define the “total” emissions 

to which EPA would compare the relevant source or source category’s emissions. In this regard, 

given the global nature of the “air pollution” at issue, EPA would need to consider, as the 

denominator in a “contribution ratio,” total global atmospheric concentrations of the GHG or 

GHGs whose emissions would be addressed through any regulatory action. See id. This 

approach would be consonant with EPA’s recognition, noted above, that “all sources of the 

contaminant which contribute to air pollution [must] be considered in the endangerment 

analysis.” Id. at 44422/3.

In discussing possible “contribution” levels, the ANPR notes potentially applicable 

percentages, such as 1.2 percent of total emissions. Id. at 44423/1-2 (citing Bluewater Network 

v. EPA, 370 F.3d 1, 15 (D.C. Cir. 2004)). The ANPR’s discussion of this issue, however, is 
25

limited and superficial, and EPA should recognize that its discretion in defining “contribution” is 

far from unbounded and must be exercised in light of its own previous determinations under the 

CAA. 

EPA should, for example, analyze the applicability of its discussion of contribution 

percentages in the context of the CAA’s “best available retrofit technology” (“BART”) program

for regional haze. The Act’s BART provision -- which, like section 202(a)(1)’s endangerment 

language, was added by Congress in the 1977 CAA Amendments -- uses “contribution” language 

similar to that in section 202(a)(1). See CAA § 169A(b)(2)(A) (BART applies to a source in 

certain specified categories of major stationary sources if it “may reasonably be anticipated to 

cause or contribute [not “significantly” contribute] to any impairment of visibility” in any 

mandatory federal Class I area (emphasis added)). In its Guidelines for implementing this 

requirement, EPA describes an appropriate test for any “contribution” -- not “significant 

contribution” -- as that amount of emissions that makes a difference in visibility that is humanly 

perceptible in the real world (a perceptibility “threshold” that EPA estimates as no smaller than a 

5 percent change in light extinction). 70 Fed. Reg. 39104, 39119-20 & n.28 (July 6, 2005). The 

point here is not that 5 percent is necessarily the “right” contribution percentage for assessing 

GHG emissions or global climate change. Rather, the point is that EPA should consider and 

discuss what amount of additional GHG emission reduction from new U.S. motor vehicles 

(beyond emission levels that would result from existing requirements) would produce a humanly 

perceptible difference in specifically identified adverse public health or welfare effects in the 

U.S. In doing so, EPA also should bear in mind its admonition in its BART Guidelines that it 

would be “inappropriate[] [to] create a ‘contribution to contribution’ test” by “aggregat[ing] the 
26

... effects of multiple sources and compar[ing] their collective effects against [the] contribution 

threshold.” Id. at 39121 n.34.

2. Application of the Endangerment Test to the “Air Pollution” at Issue 

Section V of the ANPR also discusses certain issues bearing on a determination of the 

relevant “air pollution,” including a description of GHGs and other anthropogenic factors that 

may affect global climate. This part then includes a very limited summary of scientific 

information that is more fully discussed in the draft Technical Support Document on the 

Endangerment Analysis (“Draft Endangerment TSD”).

12

Among other things, for example, the ANPR states that “climatic changes” associated 

with increases in “global temperatures” include “change in precipitation patterns, rise in sea 

levels, and changes in the frequency and intensity of extreme weather events.” 73 Fed. Reg. at 

44423/3. Yet, EPA notes, “[t]he scientific literature that assesses the potential risks and endpoint impacts of climate change ... does not assess these impacts on a gas-by-gas basis,” id. at

44424/1, thus making it particularly difficult to assess adequately whether and to what extent 

endangerment is posed by atmospheric concentrations of a single gas, such as CO2. EPA also 

states that climatic changes result from GHG concentrations in the atmosphere “as well as other 

natural and anthropogenic factors that influence the Earth’s energy balance,” id., further 

complicating the endangerment analysis. Although EPA says that it “is considering defining the 

‘air pollution’ related to GHGs as the elevated combined current and projected atmospheric 

concentration of the six GHGs,” id., one effect of that approach would be to reduce the 

likelihood that any category of sources of any of those GHGs could be deemed to make a 

12 UARG’s comments on the Draft Endangerment TSD are presented in Section V of these 

comments.
27

humanly perceptible contribution to the “air pollution,” so defined. This is particularly so given 

EPA’s recognition that climatic changes that may be associated with GHG emissions or GHG 

atmospheric concentrations are in part attributable to “other natural and anthropogenic factors 

that influence the Earth’s energy balance” as well as to “GHGs and aerosols” other than the six 

“primary” GHGs. Id.; see id. at 44424/1-44425/2 (discussing other GHGs). If EPA develops a 

notice of proposed rulemaking, it will need to discuss the relative contributions of these other 

factors and the implications of such contributions on the basis for and nature of any 

endangerment finding with respect to a source category’s emissions of any of the six primary 

gases, such as CO2. 

In discussing “observed global effects,” EPA notes, among other things, that current 

“ambient”

13 GHG concentrations “remain well below published thresholds for any direct adverse 

health effects, such as respiratory or toxic effects.” Id. at 44425/2. Likewise, EPA notes that 

projected concentrations “remain well below published thresholds for any direct adverse health 

effects, such as respiration or toxic effects.” Id. at 44426/2. EPA says, however, that 

“[w]arming of the [global] 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,” and that “[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.” Id. at 44425/3. In other words, EPA says, “the warming 

cannot be explained by natural variability alone.” Id. (emphasis added). EPA then refers 

13 EPA’s use of the word “ambient” reflects the need under the CAA to evaluate any possible 

endangerment of public health or welfare with respect to the presence of an air pollutant in the 

“ambient air,” i.e., the portion of the atmosphere to which the general public has access. This 

point is discussed in greater detail in other parts of these comments. 
28

generally to various global effects that it believes are associated with climate change, including 

precipitation changes, global sea level, and extreme temperatures. Id.

EPA also refers to temperature increases, extreme temperatures, sea level rise, and 

precipitation increases as “observed” effects in the U.S. Id. at 44426/1. A significant issue 

briefly mentioned in the discussion of projected U.S. effects is mortality -- obviously the most 

significant possible public health effect -- due to temperature changes; EPA says “[i]t is currently 

not possible to quantify the balance between decreased cold-related deaths and increased heatrelated deaths attributable to climate change over time.” Id. at 44426/3. The balance of possible 

benefits and detriments to U.S. agricultural and forest productivity is also discussed. Id. at 

44427/1.

This part of Section V concludes with a discussion of endangerment in the context of 

GHG-related “air pollution.” EPA says:

The scientific record shows there is compelling and robust evidence that observed 

climate change can be attributed to the heating effect caused by global 

anthropogenic GHG emissions. . . . Some degree of future warming is now 

unavoidable given the current buildup of atmospheric concentrations of GHGs, as 

the result of past and present GHG emissions. Based on the scientific evidence, it 

is reasonable to conclude that future climate change will result from current and 

future emissions of GHGs.

Id. at 44427/2. EPA says that “all regions of the U.S. will be affected in some way,” although 

“[t]here is a wide range in the magnitude of the[] estimated impacts,” and “[t]here [is] more 

confidence in the occurrence of some effects and less confidence in the occurrence of others.” 

Id. at 44427/2-3. Regarding possible public health effects, the ANPR says: “[T]here are indirect 

human health risks (e.g., heat-related mortality, exacerbated air quality, extreme events) and 

benefits (e.g., less cold-related mortality) that occur due to climate change. We seek comment 

on how these human health impacts should be characterized under the CAA for purposes of an 

endangerment analysis.” Id. at 44427/3. EPA adds that:
29

Some elements of human health, society and the environment may benefit from 

climate change (e.g., short-term increases in agricultural yields, less cold-related 

mortality). We seek comment on how the potential for some benefits should be 

viewed against the full weight of evidence showing numerous risks and the 

potential for adverse impacts.

Id. EPA states that information in the ANPR and the Draft Endangerment TSD “points towards 

the robust conclusion that expected rates of climate change (driven by past, present, and 

plausible future GHG emissions) pose a number of serious risks to the U.S., even if the exact 

nature of the risks is difficult to quantify with confidence.” Id. at 44428/1. EPA then solicits 

“comment on whether, in light of the precautionary nature of the statutory language, the 

Administrator needs to find that current levels of GHG concentrations endanger public health or 

welfare now.” Id. EPA concludes by inviting “comment on all issues relevant to making an 

endangerment finding, including the scientific basis supporting a finding that there is or is not 

endangerment under the CAA, as well as the potential scope of the finding (i.e., public health, 

welfare, or both).” Id. 

Although UARG presents its detailed comments on these issues in Section V (addressing 

the Draft Endangerment TSD), it offers the following general comments here.

First, in determining an appropriate response to the petition for rulemaking at issue in 

Massachusetts, EPA must consider the broad effects that regulation of new U.S. motor vehicles’

emissions may have on public health or welfare. For example, any regulation of motor vehicle 

GHG emissions under section 202 (or almost any other regulation of any other source sector’s 

GHG emissions under the existing CAA) presumably would trigger PSD regulation of emissions 

of the relevant gases. That in turn could have profoundly damaging effects on the U.S. economy, 

which in turn could harm public health or welfare to a degree that would offset any benefit from 

such motor vehicle regulation. In addition, PSD or other broadly applicable regulation of GHG 

emissions under the existing CAA could accelerate the flight of industry to other countries, 
30

especially developing countries that are unlikely to control their sources’ GHG emissions and are 

unlikely to control associated conventional-pollutant emissions to the same extent as the U.S. 

does. (Indeed, global GHG emission levels are rising only, or primarily, because of developing 

countries’ increasing emissions; emissions from developed countries such as the U.S. have 

largely stabilized.) Given the global nature of GHG concentrations in the atmosphere, and 

effects that may be attributable to those concentrations, the result might be a net detriment to 

U.S. public health or welfare. These collateral effects of possible motor vehicle regulation at 

least must be considered before EPA could rationally proceed with a proposed endangerment 

finding and proposed regulation of GHG emissions under section 202. It will be particularly 

important to consider these potentially damaging collateral effects in the context of not only the 

available information regarding potential risks of adverse effects of climate change but also the 

possible health and welfare benefits from climate change as identified in the ANPR (e.g., 

reductions in cold-weather-related mortality and increased agricultural productivity and forest 

growth).

Second, as the above comments illustrate, if EPA prepares a notice of proposed 

rulemaking, it must focus not on “global effects” but on evidence specifically of “U.S. effects.” 

EPA’s mandate is not to protect public health or welfare on a global scale but only in the United 

States. Thus, notwithstanding EPA’s discussion in the ANPR of “global effects,” EPA must 

clearly recognize that any basis that may exist for an endangerment finding is limited to U.S. 

effects only. As UARG’s comments on the Draft Endangerment TSD note in greater detail, very 

little information exists on U.S. effects on which EPA could base a finding of endangerment of 

public health or welfare.
31

Third, a focus on a balanced assessment of potential adverse and beneficial effects is 

essential to any rational determination concerning endangerment. The ANPR implicitly 

recognizes the need for such an assessment by referring to information on increased agricultural 

yields and lower cold-weather-related mortality. Instructive in this regard is American Trucking 

Ass’ns v. EPA, 175 F.3d 1027, 1051-53 (D.C. Cir.), modified on reh’g on other grounds, 195 

F.3d 4 (D.C. Cir. 1999), rev’d in part and remanded on other grounds, Whitman v. American 

Trucking Ass’ns, 531 U.S. 457 (2001), in which the D.C. Circuit held that “EPA must consider 

positive identifiable effects of a pollutant’s presence in the ambient air in formulating air quality 

criteria under § 108 and NAAQS under § 109,” id. at 1052. Although this decision did not 

specifically address the criteria for making endangerment determinations, it would be 

unreasonable for EPA to make a finding of endangerment with respect to a given pollutant 

without evaluating and weighing the potentially beneficent effects of that “pollutant’s presence” 

in the portion of the atmosphere that is relevant to an assessment of that pollutant’s potentially 

negative effects. Moreover, EPA would have to assess and compare the pollutant’s public health 

effects, including non-adverse U.S. health effects such as reductions in cold-weather deaths, with 

any effects the pollutant may have on public welfare in the U.S. 

Fourth, with respect to “contribution,” an important factor in any endangerment analysis

for new U.S. motor vehicles is the extent, if any, to which endangerment may be posed by that 

portion of motor vehicle GHG emissions that is not controlled, and will not be controlled, under 

existing provisions of law, including the Energy Policy and Conservation Act, 42 U.S.C. §§ 

6201, et seq., (with its Corporate Average Fuel Economy (“CAFÉ”) program) and the EISA, 

which includes amendments to CAFÉ that will have the effect of further reducing vehicles’ CO2

emissions. EPA should take into account the contribution of only that portion of the emissions 
32

that will remain after application of existing emission control requirements. See, e.g., 73 Fed. 

Reg. at 44388. Indeed, with new U.S. motor vehicles’ GHG emissions (and U.S. GHG 

emissions more generally) becoming a steadily smaller share of global emissions and 

atmospheric concentrations, it is unclear what basis EPA would have for concluding that any 

global-climate-related risks of adverse effects on U.S. public health or welfare would not occur 

even in the absence of those U.S. emissions. In any event, if EPA were to base any 

endangerment finding on projected future effects (a concept discussed in the ANPR), it would 

need to consider evidence that new U.S. motor vehicles’ emissions (and other U.S. emissions)

have but a small, and diminishing, effect on global atmospheric concentrations. 

Finally, as a related matter, the purpose of the CAA endangerment test, as reflected in 

Ethyl and in the legislative history to which EPA refers, is to be preventative regarding dangers

that may be posed by air pollutant emissions and concentrations. In other words, under CAA 

endangerment criteria, the purpose of regulation is to prevent or avert dangers to the public 

health or welfare. Accordingly, if EPA proposes any endangerment finding for, or any 

regulation of, GHG emissions from motor vehicles or other sources under the CAA, it must first 

evaluate to what extent the risk to the U.S. public health or welfare would actually be averted as 

a result of that regulation. In the case of the lead in motor vehicle fuels addressed in Ethyl, for 

example, there were strong reasons for EPA to believe that regulation of the lead in fuels would 

prevent at least a substantial part of the danger to public health posed by human exposure to that 

air pollutant. See, e.g., Ethyl, 541 F.2d at 31 (The Administrator “determined that absorption of 

lead automobile emissions, when added to all other human exposure to lead, raises the body lead 

burden to a level that will endanger health. He realized that lead automobile emissions were, far 

and away, the most readily reduced significant source of environmental lead.”). Thus, the Court 
33

observed, “the lead exposure problem can fruitfully be attacked through control of lead 

additives” in motor vehicle fuels. Id. at 31 n.62 (emphasis added). 

Before proceeding with any proposed endangerment finding or regulation, therefore, EPA 

would need first to analyze what concrete public health or welfare danger in the United States 

would be averted by regulation that would control or reduce GHG emissions from new U.S. 

motor vehicles, above and beyond the emission controls or reductions that would occur because 

of other statutory and regulatory requirements such as CAFÉ and EISA requirements. EPA then 

would need to determine that -- even in the face of large and ever-growing non-U.S. emissions of 

GHGs that are making steadily increasing contributions to the global pool of the asserted dangercausing pollutants -- the U.S. health or welfare danger could “fruitfully be attacked” through 

control of these U.S. emissions alone. Id. (emphasis added). In light of existing and rapidly 

growing levels of GHG emissions from other countries, and the large and increasing percentage 

of global GHG atmospheric concentrations attributable to those countries’ emissions, it is highly

questionable whether CAA regulation of new U.S. motor vehicles’ emissions (or emissions from 

any other U.S. source category) could avert any danger EPA might determine is associated with

emissions of GHGs.

V. The Draft Endangerment TSD Does Not Provide a Sufficient Basis for Making Any 

Possible Future Endangerment Determination with Regard to GHGs Under the 

CAA.

In addition to the portions of the ANPR that describe EPA’s preliminary 

conceptualization of potential GHG regulatory approaches, EPA has also released and requested 

comment on several draft Technical Support Documents, including one outlining the Agency’s 

preliminary endangerment analysis for GHG emissions (the “Draft Endangerment TSD”). 

UARG submits the following comments on EPA’s Draft Endangerment TSD. 
34

The introduction to the Draft Endangerment TSD indicates that the document: (1) 

assesses the extent to which climate change can be attributed to human activities; (2) examines a 

range of specific and quantifiable vulnerabilities, risks, and impacts due to GHGs and climate 

change; and (3) explores known or expected benefits of elevated GHG concentrations in the 

atmosphere or of climate change. Its focus, EPA states, is primarily on the United States. Draft 

Endangerment TSD at 1. As described below, however, the Draft Endangerment TSD addresses 

these three topics in only the most cursory manner. The analysis contained in the Draft 

Endangerment TSD is woefully insufficient as a potential basis for making any endangerment 

determinations under the CAA. 

Briefly, the document: (1) improperly defines the scope of GHG-related science relevant 

to an endangerment finding, rendering the information it presents fundamentally ill-suited to the 

task of supporting any endangerment determination; (2) relies on sources of information that do 

not adequately address the scientific issues relevant under the CAA; (3) contains improper and 

inaccurate characterizations of the conclusions that can reasonably be drawn from the scientific 

studies and assessments it cites; (4) fails to address the import of recent scientific studies that 

undercut the conclusions stated in the Draft Endangerment TSD; (5) fails to address adequately 

the numerous uncertainties present in the current science; and (6) exhibits bias in its failure to 

address all relevant issues fully, including the potential for positive effects associated with

climate change. The flaws identified in the remainder of this section of UARG’s comments 

represent serious problems with the Agency’s preliminary endangerment analysis. Unless these 

deficiencies and inadequacies are addressed, the Agency will lack a sufficient scientific basis on 

which to propose any determination as to whether GHG emissions from any source cause or 
35

contribute to air pollution that may reasonably be anticipated to endanger public health or

welfare. 

A. The Draft Endangerment TSD Has Improperly Defined the Scope of 

Relevant GHG-Related Science, Rendering It Unfit for Use in Assessing 

Endangerment. 

EPA states that the purpose of the Draft Endangerment TSD is “to provide scientific and 

technical support for an endangerment analysis regarding greenhouse gas (GHG) emissions 

under the Clean Air Act.” Draft Endangerment TSD at 1. The scientific and technical 

information provided in the document, however, is wholly inadequate to support an 

endangerment finding under the provisions of the Act. This failing results, in part, from a lack of 

clarity in the document as to the scope of its analysis and a persistent lack of precision in the 

identification and analysis of relevant information. By mixing relevant and irrelevant facts in a 

manner that makes it impossible to distinguish between those effects that are relevant and those 

that are not, the Draft Endangerment TSD fails to serve its intended purpose as a source of 

information to be used to assess endangerment.

First, the Draft Endangerment TSD states that it is an assessment of the 

extent to which observed climate change can be attributed to anthropogenic GHG 

emissions. . . . The term “climate change” in this document generally refers to 

climate change induced by human activities, including activities that emit GHGs. 

Future projections of climate change, based primarily on future scenarios of 

anthropogenic GHG emissions, are shown for the global and national scale.

Id. (emphasis added). 

As this quotation demonstrates, at the outset of its preliminary endangerment analysis, 

EPA is simultaneously claiming that it is assessing anthropogenic-induced climate change and 

that it is also addressing, in an unspecified manner, climate change that is not related to 

anthropogenic emissions or to GHG emissions of any sort. In further illustration of this point, 

the Draft Endangerment TSD describes the climate-related effects of changes in tropospheric 
36

ozone, anthropogenic emissions of aerosols, increases in stratospheric and tropospheric water 

vapor, changes in land cover, and changes in solar irradiance -- none of which are related to 

emissions of the GHGs that the ANPR addresses. See, e.g., id. at 20-21. 

Addressing the impacts that may result from climate change in general is not the purpose 

of the Draft Endangerment TSD, and this information does not provide support for any potential 

endangerment finding. Rather, the purpose of this document is to assess whether anthropogenic 

GHG emissions themselves endanger public health or welfare. This lack of clarity, reflected 

throughout the document, as to the scope of climate effects that are the subject of this analysis 

makes it impossible to determine whether the effects described and any potential endangerment 

are the result of anthropogenic emissions of GHGs or some combination of anthropogenic and 

biogenic emissions of GHGs and the climate-related effects that do not result from human 

activities or from GHG emissions. Because it is impossible to determine based on the analysis 

contained in the Draft Endangerment TSD what precisely might be the ultimate source of any 

putative endangerment, the document cannot serve as a basis for an endangerment finding under 

the CAA. EPA must revise this document, if it is to serve as the basis for any finding as to 

endangerment, to address only those effects that are relevant to such a finding as defined by the 

standards in the CAA.

Further, the CAA standards governing endangerment require more from EPA than 

clarification as to whether the Draft Endangerment TSD examines anthropogenic, biogenic, or 

non-GHG-based climate change. EPA also must specify whether it intends the Draft 

Endangerment TSD to serve as supportive analysis for endangerment determinations under all 

relevant CAA authorities, a subset of such authorities, or only one particular CAA provision. 

Indeed, EPA’s intentions for this document and how it is to be used are remarkably opaque. 
37

EPA never expressly states its intentions in this regard; however, in one telling section of the 

Draft Endangerment TSD, the Agency states that “[t]hese radiative forcing values are the result 

of global changes in atmospheric concentrations of GHGs ... and other factors, and are therefore 

not the result of U.S. transportation emissions in isolation.” Draft Endangerment TSD at 19 

(first emphasis in original; second emphasis added). It is unclear if this statement implies that 

other sections of the Draft Endangerment TSD are intended to reflect only purported 

transportation-related global changes, if the document is intended for use only in analysis of 

endangerment potential from transportation-related emissions while still addressing other sources 

of emissions, or if its scope is even broader.

This lack of clarity creates a host of problems. As EPA has itself acknowledged in the 

body of the ANPR, each section of the CAA requiring an endangerment finding prior to 

regulation contains its own unique standard for reaching such a determination. 73 Fed. Reg. at 

44418-19. The Draft Endangerment TSD fails to specify which of the various impacts it 

identifies, or what portion of such impacts, can be attributed to emissions from each source 

category. Indeed, it does not even attempt to describe the extent to which such an analysis is 

even possible given the state of current scientific knowledge. This is precisely the sort of 

scientific information that will be required to conduct an endangerment analysis under the 

various CAA provisions EPA proposes as potential GHG regulatory authorities in the ANPR.

In addition, the scope of the Draft Endangerment TSD is inadequately defined with 

respect to global and U.S. emissions and the effects that can be attributed to each. Because EPA 

has the authority only to regulate U.S. emissions, its endangerment analysis must provide a basis 

for determining the extent, if any, to which U.S. emissions result in endangerment. The Draft 

Endangerment TSD fails to do so. Instead, it addresses all observed and potential future climate 
38

change caused by global emissions, and devotes a considerable portion of its discussion to global 

climate change-related effects, without providing any explanation as to how those emissions or 

effects should or should not factor into an endangerment analysis. See, e.g., Draft Endangerment 

TSD at 27-28 (global precipitation), 29-30 (global sea level rise), 31-33 (changes in global 

physical and biological systems), 34-35 (global extreme events). Accordingly, the current Draft 

Endangerment TSD is written in a manner that makes it impossible to determine whether the 

effects it describes are associated with U.S. or global emissions and whether regulation of U.S. 

sources will have anything more than a negligible effect on the various impacts identified in the 

document. Moreover, the Agency acknowledges in the Draft Endangerment TSD that EPA 

tracks U.S. emissions through the development of the official U.S. GHG inventory, underscoring 

the potential to analyze only those effects that are associated with U.S. emissions. Id. at 8.

Accordingly, an analysis of those effects that can be attributed solely to U.S. emissions may be 

possible, and EPA should, at the least, describe the relevance of such an assessment to the 

standards for determining whether endangerment exists. Failure to provide this information 

leaves a gaping hole in EPA’s preliminary endangerment analysis and again renders the 

document insufficient to support any endangerment determination. 

Finally, the Draft Endangerment TSD addresses climate change-related effects that are 

wholly unrelated to U.S. impacts. Specifically, the Draft Endangerment TSD discusses potential 

effects of climate change in other nations, focusing particularly on regions, such as Africa, Asia, 

and Latin America. It asserts that climate change will affect the health of people and impact 

food production and water resources in these regions and could influence international trade. Id. 

at 113. The document fails to establish, however, that such effects have any relevance to U.S. 

public health and welfare, suggesting only that they “may have consequences that transcend 
39

national boundaries that raise concerns for the U.S.” Id. at 1. Tellingly, the Draft Endangerment 

TSD provides no scientific data by which to assess such scenarios. This speculative approach 

unjustifiably expands the scope of the issues that should be considered during an endangerment 

assessment to include issues that have not been shown to affect U.S. public health and welfare. 

Further, even where the document does address U.S. (or North American) effects, it frequently 

intersperses additional discussion of global impacts, often failing to differentiate between the 

two. See, e.g., id. at 41. By incorporating such substantial discussion of global impacts that are 

not tied to U.S. resources, the Draft Endangerment TSD does more to confuse a potential 

assessment of endangerment than it does to illuminate it. 

In sum, EPA has failed to define the scope and purpose of the analysis contained in the

Draft Endangerment TSD. Instead, the document unhelpfully commingles information 

regarding: (1) anthropogenic, biogenic and non-GHG-related climate change effects; (2) various 

sources of emissions without defining which purported effects may be associated with each 

source category; (3) global and U.S. emissions without differentiating between the effects that 

can be attributed to each category; and (4) global effects that have not been shown to have any 

relevance to U.S. public health or welfare. Because this information is presented in composite, 

without any meaningful attempt to distinguish emissions and effects that are relevant to the 

United States, it is impossible, based on the Draft Endangerment TSD, to determine whether any 

endangerment finding is justified.

B. The Draft Endangerment TSD Relies on Scientific Information that Is 

Inadequate To Assess Whether Endangerment to U.S. Public Health or

Welfare Exists.

The Draft Endangerment TSD states that it relies on a number of sources of scientific 

information as the basis for its analysis of potential endangerment from GHG-related climate 

change. Draft Endangerment TSD at 4 (stating that the document relies primarily on the Fourth 
40

Assessment Report of the Intergovernmental Panel on Climate Change (“IPCC”), synthesis and 

assessment products of the U.S. Climate Change Science Program (“CCSP”) completed and 

publicly released to date, National Research Council (“NRC”) reports, and the EPA annual 

report on U.S. GHG emission inventories). Upon reviewing the document, however, it is clear 

that EPA has relied most extensively, and in many cases exclusively, upon the analysis contained 

in the IPCC’s Fourth Assessment Report. See, e.g., id. at 11-14 (discussing historic and current

GHG emissions); id at 19 (discussing radiative forcing values). Such overwhelming emphasis on 

the IPCC’s summary of scientific knowledge is misplaced for a number of reasons.

First, EPA must more effectively acknowledge and address a critical limitation of the 

information contained in the IPCC Assessment Report. None of the reports issued by the IPCC 

addresses U.S.-specific effects in isolation as would be necessary to support an endangerment 

finding under the CAA. Instead, the IPCC Assessments are devoted primarily to global effects

and global emissions. Further, EPA has adopted the IPCC’s regional analysis of North American 

impacts, including projections for changes in temperature, precipitation, and sea level rise, 

reasoning that such effects “can be generalized for the U.S.” Id. at 53. Such an approach is at 

best questionable, and, as EPA acknowledges, not always consistent with the science. For 

instance, the Draft Endangerment TSD states “[t]his document relies heavily on the North 

America chapter of the IPCC Working Group II report, though this chapter may not provide as 

much regional detail within the U.S. as did the 2000 report, Climate Change Impacts on the 

United States: The Potential Consequences of Climate Variability and Change (NAST, 2000).” 

Id. at 5. The implications of the limited U.S.-specific discussions are apparent in the analysis of 

specific scientific issues. For instance, the Draft Endangerment TSD simultaneously cites the 

IPCC’s discussion of the effects of abrupt climate change even while acknowledging that U.S. 
41

effects “cannot be predicted with confidence.” Id. at 58-60. There is no scientific justification 

for discussing North American impacts that are not relevant to the United States, and the Draft 

Endangerment TSD’s presentation of this information makes it impossible to determine whether 

consideration of North American impacts have played any role whatsoever in EPA’s decisions as 

to what effects to address and what effects to exclude, if any. Similarly, the conclusions that the 

Draft Endangerment TSD adopts from the IPCC are frequently so vague as to lose almost all 

meaning when viewed from a U.S. endangerment analysis perspective. For instance, the 

document adopts the following IPCC North American conclusions:

For the period 1955-2005, the greatest warming occurred in Alaska and northwestern Canada, with substantial warming in the continental interior and modest 

warming in the south-eastern U.S. and eastern Canada.

Spring and winter show the greatest changes in temperature and daily minimum 

(night-time) temperatures have warmed more than daily maximum (daytime) 

temperatures. 

Id. at 27.

Although some U.S.-specific information appears in these conclusions, it is difficult to 

determine which effects apply to the United States, which apply primarily to Canada, and which 

apply only to non-U.S. resources. In the context of an endangerment analysis, such imprecision

is wholly unacceptable.

The problems stemming from this imprecision are not, moreover, rectified by EPA’s 

chosen method for validating the use of IPCC North America conclusions as a proxy for U.S.-

specific information. EPA relies on the conclusion of two IPCC Assessment Report authors 

(Christopher Field and Linda Mortsch) as proof that extrapolation from North American 

conclusions to the United States is appropriate. These authors state that the “major conclusions”

of the North America chapter “all apply to the United States” and that the topics and impacts 

discussed are “relevant to at least some locations in the United States.” Id. at 63 (emphasis 
42

added). This statement only begs further critical questions. Which conclusions are “major”? 

Which conclusions apply to which U.S. locations? And which conclusions are inapposite? The 

Draft Endangerment TSD does not answer these questions. Further, validation of the North 

America conclusions by two authors is entirely inconsistent with the procedures governing IPCC 

work, as discussed below, and is questionable scientifically and not justified adequately by EPA. 

Given that the Draft Endangerment TSD “rel[ies] heavily on the North America chapter of the 

IPCC Working Group II volume of the Fourth Assessment Report” for all of its conclusions 

regarding purported U.S. impacts, the document fails to present the type of relevant and reliable 

information that would be needed to support any endangerment finding. Id.

Finally, in addition to the scientific imprecision introduced into the endangerment 

analysis process by the draft’s adoption of general North America IPCC analysis as a proxy for 

scientific information specific to the United States, it is also important to note that the IPCC 

Assessment Report is not itself prepared in accordance with U.S. standards for scientific 

assessments. The IPCC is governed by its own “Principles Governing IPCC Work,” available at

http://www.ipcc.ch/pdf/ipcc-principles/ipcc-principles.pdf. These Principles emphasize that 

approval of the contents of IPCC Assessments is to be determined on the basis of consensus 

among IPCC member governments. Principles Governing IPCC Work at 2. In addition to the 

statutory principles established in the CAA, EPA’s Draft Endangerment TSD is subject to the 

Information Quality Act and its guidelines establishing standards for the quality, objectivity,

integrity, and utility of information disseminated by federal agencies. Pub. L. No. 106-554 

§ 515; 67 Fed. Reg. 8452 (Feb. 22, 2002). Adopting scientific conclusions of a body not subject 

to these U.S.-law requirements and “generalizing” such conclusions to stand for propositions that 

were not intended by their originator raise substantial questions as to whether the requirements of 
43

the Information Quality Act are being met. Indeed, EPA highlights this issue itself when 

describing the process for approving the IPCC Assessment Report and the Information Quality

Act procedures used during the review and approval of CCSP Synthesis and Assessment 

Products. See Draft Endangerment TSD at 3. Thus, before the information in the Draft 

Endangerment TSD could be used as the basis for any finding on endangerment, EPA would 

have to ensure that it independently concurs with the conclusions presented in the IPCC’s 

Assessment Report, would have to address the possible consequences of the IPCC’s procedures 

with respect to the conclusions reached by that body, and would have to demonstrate that it has 

complied with the Information Quality Act and its associated guidelines. 

In sum, the analysis and conclusions of the IPCC, as contained in its Fourth Assessment 

Report, is the primary basis for many of the Draft Endangerment TSD’s conclusions, including 

its most important determinations as to climate change-related effects in the United States. This 

is an inappropriate use of this information. Most of the IPCC conclusions concern global effects 

and emissions, information that serves only to cloud the state of scientific knowledge with 

respect to whether U.S. GHG emissions are associated with endangerment to U.S. public health 

or welfare. Further, adoption of the IPCC’s North America conclusions as generally applicable 

to the United States is not scientifically justifiable. It is unclear precisely which effects cited in 

the Draft Endangerment TSD are in fact relevant to the United States, and EPA’s failure to 

provide any additional analysis of this issue makes the Draft Endangerment TSD’s conclusions 

unreliable. Further, EPA’s justification for adopting the North America conclusions for the 

United States is inadequate, inconsistent with IPCC principles, and inconsistent with standards 

governing the preparation of scientific reports for use in U.S. federal agency decision-making. 

Finally, the Agency is obligated by the Information Quality Act and good scientific practice to 
44

review for itself the conclusions of the IPCC and to conduct its own analysis of the issues 

addressed by that body before adopting its conclusions. Continuing with the Draft 

Endangerment TSD’s current approach runs the considerable risk that an endangerment finding 

will be based on information that is not relevant and not appropriate for use under the CAA. 

C. The Draft Endangerment TSD Mischaracterizes the Conclusions of the IPCC 

on Which It Relies. 

In addition to the significant problems associated with the Draft Endangerment TSD’s 

heavy reliance on the Assessment Report of the IPCC, there are a number of instances where it 

appears EPA has misinterpreted information in the Assessment Report or failed to explain why it 

has adopted a viewpoint seemingly at odds with the conclusions reached by the IPCC.

As a preliminary matter, it should be noted that the Draft Endangerment TSD’s system of 

citation is insufficient and unnecessarily complicates external review of the document. In 

particular, the Draft Endangerment TSD indicates that Box 1.2 “provides guidance for the reader 

about how this document references different chapters of the IPCC reports.” Box 1.2 is missing 

from the document. See Draft Endangerment TSD at 4. Further, the document’s citation method

is ill-suited to the sources on which it relies most heavily. The IPCC Assessments and similar 

synthesis reports, which compile the results of numerous individual studies and span hundreds of 

pages, should be cited with greater specificity. Inclusion of individual page numbers and more 

thorough efforts to document the sources for specific assertions would greatly enhance the 

usefulness of the Draft Endangerment TSD and aid public review. Given the heavy emphasis 

this document places on these long-form assessments, a modified and more transparent system of 

citation would be a considerable improvement. 

The Draft Endangerment TSD also contains a number of statements that are inconsistent 

with the information contained in the sources it cites as support for various conclusions. For 
45

instance, the document states that “[t]he atmospheric concentration of CO2 in 2005 exceeds by 

far the natural range over the last 650,000 years (180 to 300 ppm) as determined from ice cores.” 

Draft Endangerment TSD at 12. It cites Chapter 2 of the IPCC’s Working Group I Report for 

this conclusion. This information, however, does not appear in that chapter, and EPA’s basis for 

this statement is unclear. A similar quotation regarding the ice core record for methane 

concentrations appears on page 13 of the Draft Endangerment TSD, and it likewise is not 

supported by the information contained in the cited IPCC report. Another technical flaw is 

contained in the Draft Endangerment TSD’s statement that “[i]ce core data show that the 

atmospheric concentration of N2O varied by less than about 10 ppb for 11,500 years before the 

onset of the industrial period.” Id. at 13. This information does not appear in the IPCC 

Assessment chapter cited as the source of these data. Indeed, the cited chapter indicates only that 

ice core data for N2O go back 2000 years. See IPCC Working Group I, Ch. 2 at 143, Forster, P. 

et al., 2007, available at http://www.ipcc.ch/pdf/assessment-report/ar4/wg1/ar4-wg1-

chapter2.pdf.

Similarly, the Draft Endangerment TSD contains some very basic scientific inaccuracies 

that are contradicted by information in the IPCC’s Assessment. For instance, the document 

states that hydrofluorocarbons (“HFCs”), perfluorocarbons (“PFCs”), and sulfur hexafluoride 

(“SF6”) are “entirely anthropogenic in origin.” Draft Endangerment TSD at 14. The IPCC, 

however, notes that these fluorinated gases come from “anthropogenic and natural sources.” 

IPCC Working Group I, Ch. 2 at 145, Forster, P. et al., 2007. Perhaps more significantly, the 

Draft Endangerment TSD also states that these gases are “increasing rapidly,” a statement that 

misrepresents the findings of the IPCC. Draft Endangerment TSD at 14. Indeed, certain of these 

gases have decreased or remained at relatively constant levels for the most recent 10 to 20 years 
46

and, as the IPCC notes, concentration levels for some PFCs have not been updated “since 1997.” 

IPCC Working Group I, Ch. 2 at 145, Forster, P. et al., 2007. 

In addition to instances where the information contained in the Draft Endangerment TSD

does not appear in the source it cites for that information, there are equally problematic 

occurrences of misinterpretation of IPCC conclusions and instances where significant caveats 

expressed by the original source are not reflected in EPA’s statements. For instance, the Draft 

Endangerment TSD regularly uses the year 1750 as the pre-industrial baseline year from which 

subsequent radiative forcing, i.e., warming or cooling effects, is measured. See, e.g., Draft 

Endangerment TSD at ES-1, 13, 19-21. The IPCC, which the Agency cites for this information, 

indicates, however, that in the period between the years 1600 and 1800, CO2 mixing ratios 

actually dropped by 5 to 10 ppm and that using 1750 as the pre-industrial index “may slightly 

overestimate the RF [radiative forcing], as the changes in the mixing ratios of CO2, CH4 and N2O 

after the end of this naturally cooler period may not be solely attributable to anthropogenic 

emissions.” IPCC Working Group I, Ch. 2 at 140, Forster, P. et al., 2007. EPA must include 

significant caveats regarding the nature of the scientific information that it incorporates in its 

analysis or else risk misrepresenting critical facts. Further, it must explain the significance of 

such caveats.

Similar misrepresentations exist with respect to the Draft Endangerment TSD’s 

discussion of methane concentrations. The document notes in passing that methane 

concentration growth rates have “declined since the early 1990s,” but it fails to explain fully the 

import of these declines. See Draft Endangerment TSD at 13. Significantly, this information is 

again provided in the very section of the IPCC Assessment cited by the Agency as its source for 

this information. First, the IPCC Assessment indicates that since the 1990s, the emissions 
47

growth rate for methane has been “close to zero” and “less than zero in 2001, 2004, and 2005,” 

the most recent years for which the IPCC examined emissions and concentration data. IPCC 

Working Group I, Ch. 2 at 142, Forster, P. et al., 2007. As the IPCC notes, the result of these 

reductions is that the estimated second largest source of GHG radiative forcing has been 

significantly reduced. The Draft Endangerment TSD, on the other hand, concludes instead in 

general and misleading terms that “[m]ethane concentrations have also risen substantially.” 

Draft Endangerment TSD at 13. This is an inappropriate misreading of the IPCC conclusions. 

Additionally, the Draft Endangerment TSD fails to include important facts noted by the 

IPCC when discussing CO2-related impacts, and its omissions create the impression that 

anthropogenic CO2 emissions will result in negative effects that are almost certain not to occur. 

In relevant part, the document states that “[c]arbon dioxide concentrations above 5% may be 

dangerous for vegetation and as concentration[s] approach 20%, CO2 becomes phytotoxic. 

Carbon dioxide can cause death of plants through ‘root anoxia’, together with low oxygen 

concentration (IPCC, 2005).” Id. at 17. The document fails to explain adequately, however, that 

these concentrations and these particular effects have been observed only in, and are relevant 

only for, areas that are exposed to massive CO2 concentrations such as those that result from

large volcanic eruptions. Indeed, the IPCC report cited by the Draft Endangerment TSD for this 

information addresses the risk of this particular type of harm in the context of hypothetical 

massive CO2 releases from carbon sequestration storage areas. IPCC, Special Report on Carbon 

Dioxide Capture and Storage at 248 (2005), available at http://www.ipcc.ch/pdf/special-reports/

srccs/srccs_wholereport.pdf. The TSD misleadingly implies that such effects could somehow 

result from atmospheric concentrations and other anthropogenic emissions -- an implication that 
48

is plainly inconsistent with the information contained in its cited source for this statement. Draft 

Endangerment TSD at 17.

The Draft Endangerment TSD also ignores salient IPCC conclusions regarding the 

positive effects of increased CO2 concentrations and minimizes the positive effects it does 

address in a manner not supported by the information contained in the IPCC Assessment. For 

instance, the Draft Endangerment TSD acknowledges that crop yields may be positively affected 

by increased CO2 concentrations but characterizes such benefits as “small” even though there is 

no similar minimization of positive crop yield effects contained in the IPCC’s analysis. Further, 

the Draft Endangerment TSD wholly ignores the potential positive impacts associated with 

increased forest productivity even though the IPCC discusses these benefits in significant detail. 

Compare id. at 16-17, with IPCC Working Group II, Ch. 5 at 282, Easterling W. et al., 2007, 

available at http://www.ipcc.ch/pdf/assessment-report/ar4/wg2/ar4-wg2-chapter5.pdf. 

It is also important to note that the IPCC’s Assessments are composed of numerous and 

lengthy individual chapters written by multiple authors and often cover overlapping material. 

Unsurprisingly, this has resulted in a number of internal inconsistencies in the IPCC’s 

conclusions. EPA should strive to identify these inconsistencies and to ensure that its Draft 

Endangerment TSD reflects the best overall summary of the state of the science. To the 

contrary, the Draft Endangerment TSD appears to take advantage improperly of the IPCC’s 

internal inconsistencies to present the most aggressive possible interpretation of that body’s 

statements. For instance, in describing the effects of enhanced CO2 levels on ocean biota, one 

IPCC chapter states that “[i]ncreasing ocean acidity due to increasing atmospheric concentrations 

of CO2 ... is very likely to reduce biocalcification of marine organisms such as corals (Hughes et 

al., 2003; Feely et al., 2004)” (emphasis added). This chapter goes on to state, however, that the 
49

“limited number of studies available makes it difficult to assess confidence” levels for this 

conclusion. A separate IPCC chapter comes to a strikingly different conclusion, finding with 

“medium confidence levels” that increased CO2 levels in conjunction with climate change could

have negative impacts on these same marine organisms. Compare Working Group II Ch. 19

Schneider S. H. et al., 2007, with Working Group II Ch. 4 at 213, 234, Fischlin A. et al., 2007, 

available at http://www.ipcc.ch/pdf/assessment-report/ar4/wg2/ar4-wg2-chapter19.pdf; http://

www.ipcc.ch/pdf/assessment-report/ar4/wg2/ar4-wg2-chapter4.pdf. Instead of addressing these 

inconsistencies or even selecting (and supporting) one conclusion over the other, the Draft 

Endangerment TSD combines the statements contained in these two chapters and eschews all 

discussion of uncertainties and limitations to conclude that ocean acidification “will” result in 

harm to carbonate-based marine species. Draft Endangerment TSD at 17.

Finally, the Draft Endangerment TSD includes many statements for which it provides no 

citation at all. For instance, the document asserts that elevated CO2 levels could reduce the 

quality and nutritional value of animal forage grasses without identifying any basis for this 

assertion. Id.

In sum, the Draft Endangerment TSD contains a number of factual assertions that are not 

supported by the materials it cites. Certain of these instances result from discrepancies between 

the statements made by EPA and those contained in the Assessment Report of the IPCC. Others 

are the result of EPA’s mischaracterization of IPCC statements and its exclusion of relevant 

additional information. Finally, there are problems resulting from simple lack of citations for or 

clarity regarding the source of EPA’s information. These flaws must be redressed if the science 

is to be presented in an unbiased and complete manner. EPA should undertake a thorough 
50

review of the Draft Endangerment TSD and the reports it cites to ensure that these problems are 

rectified.

D. Recent Individual Studies Undercut Conclusions Contained in EPA’s Draft 

Endangerment TSD and the Reports on Which It Relies.

The Draft Endangerment TSD fails to take into account several more recent scientific 

studies that pose serious challenges to a number of the document’s statements and that 

undermine certain key assumptions that have been relied on in the scientific literature that the 

document reviews. This section of the comments describes the source material EPA has chosen 

to rely on, observes that additional sources should be included, and highlights major recent 

findings of significance to any endangerment analysis. 

As stated above, the Draft Endangerment TSD relies almost exclusively on the Fourth 

Assessment Report of the IPCC for the vast majority of its factual assertions and conclusions. In 

addition, the Draft Endangerment TSD states that it “relies most heavily on existing, and in most 

cases very recent, synthesis reports of climate change science and potential impacts, which have 

gone through their own peer-review processes including review by the U.S. Government.” Draft 

Endangerment TSD at 4. EPA states that it is appropriate to rely on these reports because:

[T]hey 1) are very recent and represent the current state of knowledge on climate 

change science, vulnerabilities and potential impacts; 2) have assessed numerous 

individual studies in order to draw general conclusions about the state of science; 

3) have been reviewed and formally accepted by, commissioned by, or in some 

cases authored by, U.S. government agencies and individual government 

scientists and provide EPA with assurances that this material has been well vetted 

by both the climate change research community and by the U.S. government; and 

4) in many cases, they reflect and convey the consensus conclusions of expert 

authors.

Id. Further, EPA states that the Draft Endangerment TSD also “often cites those individual 

studies that tended to be very influential in the more general findings of IPCC, CCSP [sic]; 
51

however, every effort is made to make it clear when an individual reference was incorporated 

into one of the broader assessments.” Id. at 5-6.

Thus, it does not appear that EPA has engaged in a literature review in an attempt to 

identify all of the most recent relevant studies addressing the issue of climate change and its 

projected effects. EPA states that a critical factor in selecting these synthesis reports as the basis 

for the Agency’s preliminary endangerment analysis is the conclusion that they “represent the 

current state of knowledge on climate change.” Id. at 4. A number of EPA’s identified “core 

reference documents” were released within the last two years, although five of the fifteen 

documents were released between 2001 and 2006. Id. Further, these reports are themselves 

necessarily based on studies that predate them and, given the rapidly evolving nature of climate 

science, could easily now be considered obsolete. Moreover, given that research into climate 

change-related impacts is in its infancy, it is especially important that EPA, in drafting an 

analysis of such impacts, include the most up-to-date information available. See Eli Kintisch,

“Climate Change: Impacts Research Seen As Next Climate Frontier,” Science Vol. 322. no. 

5899 at 182-83 (Oct. 10, 2008). Moreover, EPA appears to acknowledge the importance of 

discussing the results of important individual studies even where they have been addressed in 

larger synthesis reports, even though the Draft Endangerment TSD rarely discusses such studies. 

It follows that it is at least as important to address those studies that have been released after the 

preparation of these synthesis reports and to assess whether they alter or undermine any of those 

reports’ underlying assumptions or conclusions.

The studies described below all undercut or otherwise significantly revise information 

presented in the Draft Endangerment TSD. They illustrate the importance to the document’s 
52

reliability of a comprehensive review of the scientific developments that have occurred since the 

release of the synthesis reports on which EPA relies.

First, it is particularly noteworthy that the Draft Endangerment TSD identifies climate 

change as a projected source of future increases in ozone and particulate matter concentrations 

with potential negative human health impacts. Draft Endangerment TSD at 60, 70-75. The 

information contained in the Draft Endangerment TSD regarding these supposed impacts is 

strikingly different from and less nuanced than EPA’s own recently released analysis of these 

same issues. See EPA, Assessment of the Impacts of Global Change on Regional U.S. Air 

Quality: A Preliminary Synthesis of Climate Change Impacts on Ground-Level Ozone, 

EPA/600/R-07/094 (March 2008) (“Assessment Report”). That EPA analysis indicates that 

some regions of the United States are likely to experience ozone decreases associated with 

climate change (see, e.g., id. at xvii, 3-7, 3-17), that reductions in ozone precursor emissions will 

likely overwhelm any increases that may result from climate change (id. at 4-4), and that 

ultimately the science in this area is riddled with uncertainties with respect to ozone and 

particulate matter (see, e.g., id. at 1-10, 1-11). EPA should ensure that the Draft Endangerment 

TSD is consistent with its own analysis of these issues presented in other forums (or at least 

explain and justify the inconsistencies), and the Agency should update the Draft Endangerment 

TSD with the more recent information it addresses in its ozone and particulate matter 

assessment.

A number of recent studies indicate that certain previously projected effects of climate 

change will be less severe than was once anticipated or are, in fact, less certain to occur at all. 

The Draft Endangerment TSD, on the other hand, fails to note these recent changes in the state of 

the science. For instance, the Draft Endangerment TSD notes that hurricanes have trended 
53

toward increased destructiveness and that such storms are likely to become more intense. Draft 

Endangerment TSD at 35, 57. It also cites a variety of projected effects of such storms, such as 

diseases, drowning, damage to forest systems, destruction of human habitat and resources, and 

coastline loss. Id. at 67, 83, 95-96, 99, 101. Significantly, however, the document does not 

address the implications of a recent and important new study finding hurricanes are likely to be 

substantially rarer events under projected climate conditions. Thomas R. Knutson et al., 

“Simulated Reduction in Atlantic Hurricane Frequency Under Twenty-First-Century Warming 

Conditions,” Nature Geoscience Vol. 1 at 359-64 (2008). This finding could considerably revise 

the estimates of all of these impacts and should be incorporated into the Draft Endangerment 

TSD’s analysis.

Similarly, the Draft Endangerment TSD devotes considerable discussion to ice sheet 

collapse, including abrupt ice sheet changes, Draft Endangerment TSD at ES-3, and states that 

ice sheet melting is a major component of projected sea level rise, an additional impact that 

receives considerable attention, id. at 30, 53. The document also speculates that rapid melting 

due to increased ice flow could hasten these projected changes. Id. at 53, 58-59. A recent study, 

however, indicates that ice sheets are less susceptible to climate change-related loss of mass than 

has previously been suggested. In particular, this study reported that ice sheets can adjust to 

what were assumed to be feedback mechanisms that were thought to cause accelerated melting, 

thus indicating that abrupt melting from increased ice flow is unlikely. See R.S.W. van de Wal, 

et al., “Large and Rapid Melt-Induced Velocity Changes in the Ablation Zone of the Greenland 

Ice Sheet,” Science Vol. 321 no. 5885 at 111-13 (July 4, 2008). Thus, this study raises 

substantial questions as to a number of the Draft Endangerment TSD’s assertions and requires 

reconsideration of the additional projected impacts that the draft seeks to tie to ice sheet loss. 
54

Further, an additional study indicates that ocean temperatures have not risen in response to 

anthropogenic climate change and that any increase in ocean temperature is regional in nature 

and the result of natural variability. M. Susan Lozier et al., “The Spatial Pattern and 

Mechanisms of Heat-content Change in the North Atlantic,” Science Vol. 319 no. 5864 at 800-03 

(Feb. 8, 2008). Without addressing this study, however, the Draft Endangerment TSD asserts 

that ocean warming is unequivocal and that it is contributing, and will continue to contribute, to 

sea level rise. Draft Endangerment TSD at ES-1, 21, 30. Again, these findings should be 

reexamined in light of the new evidence and modified, as appropriate, to reflect the new 

information.

The Draft Endangerment TSD also points to a number of negative impacts that it projects 

will affect the health of the nation’s water-based ecosystems, including rivers. In particular, the 

document notes that rivers may experience increases in river bottom sediment suspension, 

affecting water quality and river discharge. Id. at 89, 91. EPA suggests that these changes in 

river discharge will, in turn, negatively impact water management, park tourism, winter sport 

activities, inland water sports (e.g., fishing, rafting, and boating), and other recreational uses. Id. 

at ES-8, 33. Further, the Draft Endangerment TSD states that increased river discharge in the 

Arctic will accelerate future climate change and further impact water supplies. Id. at 88. All of 

these assumptions are significantly undercut by a recent study finding that, while climate-related 

changes in precipitation could theoretically affect river discharge, few rivers have experienced 

any significant changes to date, and any changes that might occur in the future are much more 

likely to be caused (or overwhelmed) by factors unrelated to climate change, such as damming 

and irrigation. J.D. Milliman et al., “Climatic and Anthropogenic Factors Affecting River 

Discharge to the Global Ocean, Global and Planetary Change Vol. 62 at 187-94 (2008).
55

The Draft Endangerment TSD also devotes considerable discussion to projected impacts 

on various species. For instance, the Draft Endangerment TSD states that climate change may 

assist in the spread of animal diseases. Draft Endangerment TSD at 79, 108. While examination 

of this area of the science is only beginning, it is important that EPA not overstate the likelihood 

or severity of potential effects and that it temper its speculation. This is especially the case 

because recent scientific analysis has determined that animal diseases previously thought to have 

been exacerbated by changing climatic conditions have been shown to have, in fact, been 

unrelated to climate. Karen R. Lips et al., “Riding the Wave: Reconciling the Roles of Disease 

and Climate Change in Amphibian Declines,” PLOS Biology Vol. 6 no. 3 at 441-54 (Mar. 2008)

(finding that amphibian declines due to disease increases are not related to climate change). 

There is also recent evidence indicating that previously common assumptions regarding the 

species level impacts of changing temperatures and the distribution of species impacts are 

undermined by some serious inaccuracies. Curtis A. Deutsch, et al., “Impacts of Climate 

Warming on Terrestrial Ectotherms Across Latitude,” PNAS Vol. 105 no. 18 (May 6, 2008). 

Particularly important is the finding that species impacts will likely be greatest in the tropics, 

outside of the United States, and that species in higher latitudes are far more resilient to climate 

change. Id. at 6668-72. The Draft Endangerment TSD, on the other hand, indicates only that 

many species are likely to be negatively affected by temperature changes as they are living at or 

near their temperature thresholds. Draft Endangerment TSD at ES-6, 79-80.

Although all of the studies mentioned above have important implications for current 

scientific understanding of climate change impacts and reflect the need for reconsideration of 

specific conclusions contained in EPA’s preliminary endangerment analysis, perhaps the most 

significant new information is that which calls into question important temperature record data 
56

that are fundamental to our ability to project and understand potential climate change. This 

information has significant implications for the reliability of modeling results in that a model’s 

ability to project future climate is assessed based on its ability to replicate past climate 

developments accurately based on available temperature records. Moreover, the data from the 

temperature record are used as an input in climate models, and thus dictate how they will 

perform. There are a number of studies that fall into this category. Regarding ocean 

temperatures, one study has recently uncovered previously undocumented biases that have 

resulted in significant overestimation of long-term temperature changes in the global ocean. 

Victor Gouretski and Klaus Peter Koltermann, “How Much Is the Ocean Really Warming?,” 

Geophysical Research Letters Vol. 34 at L0610 (Jan. 12, 2007). The significance of the ocean 

temperature record was recently demonstrated by Keenlyside et al., who found that use of more 

accurate sea surface temperatures resulted in global surface temperature projections that, over the 

next several decades, would fall within natural climate variability. N.S. Keenlyside et al., 

“Advancing Decadal-scale Climate Prediction in the North Atlantic Sector,” Nature Vol. 453 at 

84-88 (May 2008). Similarly, several recent studies have uncovered comparable flaws, 

uncertainties, and biases in the multidecadal surface air temperature record. David W.J. 

Thompson et al., “A Large Discontinuity in the Mid-twentieth Century in Observed GlobalMean Surface Temperature,” Nature Vol. 453 at 646-49 (May 29, 2008); Roger A. Pielke, Sr. et 

al., “Unresolved Issues With the Assessment of Multidecadal Global Land Surface Temperature 

Trends,” Journal of Geophysical Research Vol. 112 at D24508 (Dec. 29, 2007); Roger Pielke, 

Sr. et al., “Documentation of Uncertainties and Biases Associated with Surface Temperature 

Measurement Sites for Climate Change Assessment,” American Meteorological Society at 913-

28 (June 2007); X. Lin et al., “An Examination of 1997-2007 Surface Layer Temperature Trends 
57

at Two Heights in Oklahoma,” Geophysical Research Letters Vol. 34 at L24705 (Dec. 22, 2007). 

These findings require reanalysis of modeling results previously relied on by the IPCC and the 

other synthesis reports cited by EPA as they are likely to have similarly significant effects on 

climate projections. These changes could fundamentally alter projections with respect to all 

other purported climate change-related impacts.

Other studies, unrelated to discrepancies in the temperature record, also indicate that 

other similarly pervasive inaccuracies may affect past climate modeling projections and require 

considerable reexamination. For instance, Spencer and Braswell, 2008, determined that previous 

estimates of the sensitivity of the climate system based on satellite data were biased toward the 

high side due to the neglect of natural cloud variability. Roy W. Spencer and William D. 

Braswell, “Potential Biases in Feedback Diagnosis from Observational Data: A Simple Model 

Demonstration,” Journal of Climate Vol. 21 no. 21 at 5624-28 (Nov. 2008). This study

determined that the failure to account for natural, chaotic cloud variability, a problem that 

continues to plague climate modeling, will always project a climate system that appears more 

sensitive than it really is. In another recent study, V. Ramanathan and G. Carmichael, “Global 

and Regional Climate Changes Due to Black Carbon,” Nature Geoscience Vol. 1 at 221-27 (Apr. 

2008), the authors demonstrated that global climate models consistently underestimate the 

percentage of climate forcing that is attributable to black carbon, a non-GHG. Further, a number 

of impacts associated with black carbon, including reduction of sea ice and snow albedo, were 

shown to dwarf similar effects that have been attributed to CO2.

The Draft Endangerment TSD’s analysis of these scientific issues is outdated. It fails to 

take into account any of the serious implications these studies have for previously performed 

modeling of projected climate change and the cascading effects attributed to that modeling. 
58

Indeed, the Draft Endangerment TSD notes only in passing that inaccuracies, such as those 

described here, in surface and ocean temperature records may result in random biases that 

“likely” cancel one another out. Draft Endangerment TSD at 22. It is evident from the current 

scientific record that that is not the case. EPA therefore must significantly revise the Draft 

Endangerment TSD to reflect this new information, and it should engage in a thorough reanalysis 

of the scientific data to arrive at more accurate projections of climate change and its potential 

effects. Further, the Agency must strive to identify all other relevant scientific information, as 

exclusive reliance on older synthesis assessments is inadequate.

E. Uncertainty Is Not Adequately Reflected in the TSD’s Analysis.

In addition to the other flaws identified in these comments regarding the nature and 

quality of its scientific analysis, the Draft Endangerment TSD consistently fails to incorporate 

adequate discussion of the uncertainties that characterize the science it addresses. Such 

information is critical to a thorough and reasoned understanding of the state of the science and 

cannot be avoided for the sake of simplicity or any other purpose. Nevertheless, EPA indicates 

that uncertainties and confidence levels are reported in the Draft Endangerment TSD only “to the 

extent that such information was provided in the original scientific reports upon which [the TSD] 

is based.” Draft Endangerment TSD at 3. This approach is not adequate. First, the IPCC 

Assessment Reports make up the bulk of the sources on which the Draft Endangerment TSD

relies, and they regularly report uncertainties associated with their conclusions. The Draft 

Endangerment TSD, however, seldom reports this information. Moreover, given the fact that the 

document is based almost exclusively on synthesis reports, even where those reports do not 

address uncertainties, it is imperative that EPA examine the underlying studies analyzed in them

and attempt to determine and describe the uncertainties as discussed by the authors. Finally, 

even in the absence of uncertainty analysis in underlying studies, EPA should attempt to address 
59

whether uncertainties or other complications were likely before reporting the results of such 

studies. 

In numerous cases, the Draft Endangerment TSD fails to state with any clarity whether 

uncertainties exist. This leaves the impression that it is irrefutable that the described effects will 

occur, an impression that is in almost every case erroneous. For instance, within a few short 

paragraphs, the Draft Endangerment TSD reports that animal forage may be negatively impacted 

by CO2 levels, that extremely high CO2 levels in soil can cause root anoxia and result in 

significant vegetation loss, and that increased CO2 levels could directly cause ocean acidification

and “impair a wide range of planktonic and other marine organisms.” Draft Endangerment TSD

at 17. Nowhere in this litany of purported negative effects does EPA address the likelihood that 

any of these effects will occur, or describe the number or quality of the studies supporting these 

conclusions, or make any mention of uncertainties. EPA’s characterization of various effects, in 

addition to the examples noted here, and their likelihood of occurrence should be clear and 

adequately supported by the science, or they should be removed from the document.

Elsewhere, uncertainties are noted in passing while their implications are utterly ignored 

or glossed over. This, too, gives the impression that the uncertainties are minimal and are likely 

to be resolved in favor of the worst case scenario that EPA presents. For instance, the Draft 

Endangerment TSD devotes considerable space to a discussion of projected increased tropical 

cyclone activity and the associated impacts of such storms. Id. at 34-36, 40, 57, 67. The 

document notes that “[m]ulti-decadal variability and the quality of the tropical cyclone records 

prior to routine satellite observations in about 1970 complicate the detection of long-term trends 

in tropical cyclone activity.” Id. at 36. The document fails to indicate the importance of the lack 

of a clear trend, which could signal that such storms are unrelated to climate change or that its 
60

effects on storm activity are unknown. Instead, the document treats this lack of information as if 

it has no bearing on its remaining assertions as to tropical cyclone impacts. 

In addition, the Draft Endangerment TSD, while discussing the effects of climate change 

on various ecosystems, notes in passing that human system responses to climate change are 

“more difficult to identify and isolate due to the larger role that non-climate factors play (e.g., 

management practices in agriculture and forestry, and adaptation responses to protect human 

health against adverse climatic conditions).” Id. at 41. Nevertheless, the Draft Endangerment 

TSD discusses in considerable detail -- without noting uncertainties at all -- a wide range of

human health effects that it attributes to climate change. Id. at 64-69. It is misleading to avoid 

discussion of these issues entirely in the chapters that purportedly address them while slipping in 

references to significant uncertainties in a section of the document that is unrelated to human 

health effects. The Draft Endangerment TSD must redress this significant failure.

Similarly, the Draft Endangerment TSD discusses and relies on the GHG emission 

scenarios, as well as their associated implications for future radiative forcing and temperature, 

precipitation, and sea level impacts, identified in the IPCC’s 2000 Special Report on Emission 

Scenarios. Id. at 42. It also cites the emission scenarios described in CCSP Synthesis Report 2.1 

and the most recent IPCC Assessment as evidence that newer studies have not significantly 

altered projections. Id. at 43, 44. The TSD acknowledges, however, that there are a number of 

uncertainties in these projections. See, e.g., id. at 45. Further, it states that they do not take into 

account GHG mitigation policies in either the United States or the rest of the world, including 

the Kyoto Protocol or any other likely future regulation. Id. at 42. Thus, these emission 

scenarios are subject to considerable doubts as to their accuracy. Yet, this information and its 

significant implications for all of the projected effects described elsewhere in the Draft 
61

Endangerment TSD are left wholly unaddressed. EPA needs to convey adequately the relevance 

of these uncertainties and indicate that they substantially affect the remainder of the document’s 

analysis. 

Similarly, far-reaching uncertainties go unaddressed in the Draft Endangerment TSD’s 

discussion of climate modeling. The TSD describes climate change models as “well-tested,” 

characterized by a “foundation in accepted physical principles,” and possessing the “ability to 

reproduce observed features of current climate and past climate changes.” Id. at 37. These 

assertions are overbroad and ignore critical shortcomings in modeling capabilities. As stated in a 

2008 CCSP Report, current models contain “a number of systematic biases,” their strengths and 

weaknesses “vary substantially” from model to model, and “several important aspects of the 

climate system present especially severe challenges to the goal of simulation.” CCSP, Climate 

Models: An Assessment of Strengths and Limitations at 1 (July 2008). This report goes on to 

characterize in significant detail a variety of uncertainties and problems posed by current models, 

none of which is addressed adequately in the Draft Endangerment TSD. Moreover, in the few 

instances where model inconsistencies or uncertainties are mentioned, they are explained away 

as “under investigation” while their implications are left unaddressed. See, e.g., Draft 

Endangerment TSD at 39-40, 49. Again, these significant issues should not be ignored. 

The Draft Endangerment TSD should be revised to include discussion of uncertainties 

and to explain their meaning. Merely acknowledging that some uncertainty may exist while 

failing to address its implications does a disservice to the scientific understanding of these 

complex issues.
62

F. The Draft Endangerment TSD Contains Numerous Examples of Bias and 

Speculation that Are Inconsistent with the Scientific Evidence.

The analysis in the Draft Endangerment TSD is undermined, even where it may

otherwise be sound, by a number of statements that could be interpreted as indicating bias. This 

bias is demonstrated in several ways. Of particular importance is information identified in the 

Draft Endangerment TSD as potentially significant but nonetheless excluded from analysis and 

consideration. EPA fails to make a compelling argument that this information should not be 

considered in assessing endangerment, thereby giving the appearance that its exclusion from the 

Draft Endangerment TSD is, at best, arbitrary and, at worst, designed to lead to a particular 

conclusion on the endangerment issue. 

For instance, the Draft Endangerment TSD states that “[a]daptation to climate change is a 

key focus area of the climate change research community.” Draft Endangerment TSD at 1. 

Nevertheless, EPA has determined that it is inappropriate to focus on adaptation in conducting its 

scientific assessment of endangerment issues, and it even suggests that the Administrator may 

not consider adaptation in assessing the possibility of endangerment. Id. at 118. Further, the 

Agency states that “mitigation measures to reduce GHGs, which could also reduce long-term

risks, are not addressed.” Id. at 1-2. The Agency’s stated rationale for these exclusions is that 

the purpose of the Draft Endangerment TSD “is to review the effects of climate change rather 

than society’s response to climate change.” Id. This reasoning is unsatisfactory and has led to a

preliminary endangerment analysis that, in essence, ignores reality.

14 First, as EPA notes, 

14 Indeed, EPA’s reasons for distinguishing between “acceptable” and “unacceptable” fields of 

scientific inquiry is particularly unconvincing given that the IPCC deemed it appropriate to 

devote an entire Working Group Report to adaptation and mitigation -- a report that the Draft 

Endangerment TSD wholly ignores -- even as EPA has opted to rely almost exclusively on other

IPCC Working Group Reports. 
63

mitigation measures may themselves limit the effects of climate change, the extent of which is 

among the necessary areas of inquiry in an endangerment analysis. It is entirely inconsistent to 

assess the effects of anthropogenic GHG emissions without considering those anthropogenic

actions that might limit those emissions or their impacts. Further, even while adaptation will not 

likely limit GHG emissions directly, there is no practical difference between minimizing 

emissions and minimizing the effects of emissions. In each case, the ultimate result is less likely 

or more limited climate change impacts, with the difference having a bearing on the 

endangerment question. Ignoring the possibility that GHG emissions will not result in 

endangerment because of adaptation or mitigation is unscientific and must be rectified.

Similarly, the Draft Endangerment TSD notes that it is relying on EPA’s annual 

Inventory of U.S. Greenhouse Gas Emissions and Sinks for information regarding the primary 

GHGs of interest and indicates that this information is used to project the effects of climate 

change. Id. at 1. Further, the document states that this U.S. inventory does not account for 

emissions and sinks resulting from land use changes and the forestry sector. Importantly, in the 

United States, the forestry sector is “a significant sink, while in some developing countries it is a 

significant net source of emissions.” Id. at 9. First, exclusion of a significant U.S. carbon sink 

results in a bias toward a finding that U.S. emissions will result in or contribute to endangerment. 

Further, the Draft Endangerment TSD ignores other significant carbon sinks, a fact that further 

biases the analysis in the document in the direction of a finding of endangerment. See, e.g., id. 

(“Removals of carbon through land use, land-use change and forestry activities are not included 

in Figure 2.2, but are significant; net sequestration is estimated to be 828.5 TgCO2eq in 2005, 

offsetting 11.4% of total emissions (EPA, 2007).”). This problem is exacerbated by the fact that 

EPA’s global emissions estimates may indeed include forestry-related emissions and sinks from 
64

other countries, thereby skewing the Agency’s assessment of the relative importance of U.S. 

emissions. See id. at 11 (“Excluding land use, land-use change, and forestry, U.S. emissions 

were 20% of the total year 2000 global emissions ....”). EPA must clarify what sinks and 

emission sources, both in the U.S. and internationally, are taken into account in its endangerment 

assessment. Further, to ensure that the Agency’s analysis of the endangerment issue is based on 

the most complete record possible, an adequate representation of U.S. carbon sinks must be 

incorporated.

Finally, the Agency wholly excludes any discussion of hydroxyl free radical in limiting 

the impacts of GHGs. This information is prominently featured in chapters of the IPCC 

Assessment Report cited extensively in the Draft Endangerment TSD, and the IPCC has 

characterized it as playing a “very significant role” in mitigating climate change effects. IPCC 

Working Group I, Ch. 2 at 147, Forster, P. et al., 2007.

In addition to the irrational exclusion of key scientific information, the Draft 

Endangerment TSD indicates bias through unfounded speculation about possible effects of 

climate change that are in no way supported by the scientific evidence discussed in the 

document. For instance, the Draft Endangerment TSD states that “[i]t is likely that there have 

been increases in the number of heavy precipitation events (e.g., 95th percentile) within many 

land regions, even in those where there has been a reduction in total precipitation amount, 

consistent with a warming climate and observed significant increasing amounts of water vapor in 

the atmosphere.” Draft Endangerment TSD at 28 (emphasis added). The Agency, however, 

provides no citation and no evidence for this assertion. Indeed, elsewhere in the Draft 

Endangerment TSD, the Agency notes that “only a few regions have sufficient data to assess 

such [precipitation] trends reliably.” Id. at 35. Accordingly, it is improper to suggest that other 
65

regions have also experienced similar precipitation events in the absence of evidence for such 

effects. Similarly, the Draft Endangerment TSD states that significant effects “may” occur as a 

result of abrupt climate change, thus engaging in considerable speculation even as the Agency 

acknowledges substantial uncertainty. Id. at 59-60. Likewise, the Draft Endangerment TSD

notes that there is insufficient current scientific knowledge to determine the effectiveness of 

adaptation. Id. at 119. Despite this, the Agency concludes without a basis that adaptation 

mechanisms will not be sufficient to respond to all aspects of climate change. Id. at 119-120.

Finally, the Draft Endangerment TSD states that “[i]t is believed that on average, over the 

period from 1961 to 2003, thermal expansion contributed about one-quarter of the observed sea 

level rise, while melting of land ice accounted for less than half; the full magnitude of the 

observed sea level rise was not satisfactorily explained by the available data sets (Bindoff et al., 

2007).” Id. at 30 (emphasis added). Indeed, the uncertainties in this area are underscored 

particularly well by the scientific assertions put forward by petitioners in Massachusetts v. EPA

to support their arguments that petitioners had standing to bring the case. In affidavits filed in 

that case, at least one of petitioners’ scientific experts conceded that sea level rise will occur 

“regardless of” global climate change and that, at least with respect to some areas of the country, 

naturally occurring “land subsidence also contributes significantly to sea level rise.” 

Massachusetts v. EPA, Kirshen Decl. ¶ 6, Standing App. at 197. Again, it is inappropriate to 

suggest scientific conclusions in the absence of available data. These speculative statements tend 

to suggest that climate change will result in effects for which evidence is lacking. EPA must 

more accurately present the state of the science and avoid speculation as to significantly 

uncertain potential effects. 
66

In sum, the Draft Endangerment TSD displays a number of biases that minimize 

important scientific information that tends to support a finding of less likely, less severe, or less 

extensive GHG- or climate change-related effects. Further, the document includes numerous 

instances of unfounded speculation that tend to overstate the extent of various climate changerelated effects or that portray the likelihood that certain effects will occur as more certain than 

the science supports. EPA must redress the specific flaws identified in these comments and

review and revise the Draft Endangerment TSD to ensure that all similar problems are addressed. 

G. The TSD’s Conclusions as to Climate Change-Related Effects on Specific 

Health and Welfare Resources Must Be Revised To Address the Scientific 

Flaws Identified in the Comments.

As explained above, there are numerous and varying flaws in the analysis and underlying 

data relied on by EPA in the Draft Endangerment TSD. These problems undermine the 

document’s conclusions with respect to the specific observed and projected U.S. human health 

and welfare effects from climate change. Because these flaws go to the fundamental scientific 

bases for many of the Draft Endangerment TSD’s assertions, EPA must revisit its statements 

with respect to likely effects of climate change on: human health; air quality; food production 

and agriculture; forestry; water resources; sea level rise and coastal areas; energy, infrastructure,

and settlements; and ecosystems and wildlife. For the sake of clarity, this section of these 

comments addresses the key flaws undermining the reliability of the Draft Endangerment TSD’s 

statements as to each of these health and welfare interests and identifies areas in which the 

document would have to be revised to reflect the current science adequately. 

1. Human Health

Several of the Draft Endangerment TSD’s statements regarding the purported human 

health impacts of climate change require revision for the reasons identified in the previous 

sections of these comments. First, the document observes that climate change is projected to 
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have both positive and negative health effects and states that “[t]he balance of positive and 

negative health impacts will vary from one location to another, and will alter over time as 

temperatures continue to rise.” Draft Endangerment TSD at 64. EPA goes on to address in 

substantial detail numerous potential negative outcomes, devoting substantially more space to 

negative than to positive outcomes. This approach overemphasizes potential negative effects, 

even as EPA notes that it is unclear whether positive or negative impacts will be greater. Id. at 

64-66. The Agency must effectively present the uncertainties in this area of inquiry and must 

adequately explain the difficulties in assessing human health impacts that result from problems 

in accounting for the capacities of human response systems. See id. at 41. 

For similar reasons, the Draft Endangerment TSD must revise its assertions regarding

likely impacts on human health from climate change-related floods and storms as well as their 

possible secondary effects, such as increases in disease. Moreover, the information contained in 

recent scientific studies not addressed in the Draft Endangerment TSD indicates that these effects 

may be less extensive than the Draft Endangerment TSD acknowledges. Id. at 66-67. Further, 

the potential of mitigation and adaptation to minimize such impacts further should be considered 

and quantified. See id. at 68 (noting that disease impacts will be “strongly modulated by changes 

in health care, infrastructure, technology, and accessibility to health care.”). Reanalysis of these 

issues is thus necessary.

In addition, a number of specific uncertainties should also be better reflected in this 

section of the document’s analysis. Specifically, the Draft Endangerment TSD asserts that 

climate change will result in additional allergenic illnesses in approximately 20% of the U.S. 

population. Id. This assertion, however, is unfounded. Indeed EPA acknowledges that there is 

only a limited understanding of aeroallergens and their effects on sensitization of individuals. Id. 
68

Similarly, even while acknowledging the paucity of studies addressing “the interaction effects of 

multi-sector climate impacts (they may be nonlinear) or of interactions between climate change 

health impacts and other kinds of local, regional, and global changes,” EPA’s analysis 

demonstrates that the Agency assumes that such studies would demonstrate additional negative 

impacts as opposed to possible mitigation. Id. at 64. Again, EPA may not properly substitute 

speculation for adequate information.

Finally, EPA must also consider the relevance of general information about potential 

human health effects. Information that does not assess specific effects is of very limited 

relevance to the endangerment question.

2. Air Quality

This section of the TSD cites the IPCC for the conclusion that air quality in cities is 

virtually certain to decline due to climate change. Id. at 70. It concludes that these projected 

changes are associated with the expected influence of climate change on biogenic emissions, 

chemical reaction rates, precipitation, and weather pattern modification. Id. As stated above, 

various recent studies suggest that the projections of these effects on which EPA relies require 

revision, and EPA accordingly would have to revisit these issues before it could propose any

endangerment finding. Additionally, the Draft Endangerment TSD specifically cites changes 

projected in particulate matter and ozone as the primary sources of decreased air quality 

supposedly resulting from climate change. Id. at 70-75. Again, EPA’s own recent analysis of 

these issues indicates that particulate matter effects are especially uncertain and that ozone 

concentrations may decrease in substantial portions of the United States. Assessment Report at 

3-7, 3-17. Moreover, it is possible that ozone concentration increases resulting from climate 

change will be more than offset by reductions in anthropogenic precursors of ozone. 
69

Accordingly, the Draft Endangerment TSD’s air quality conclusions must be revised to reflect a 

more accurate presentation of the science. 

In addition, this section of the Draft Endangerment TSD notes various uncertainties 

without addressing their implications for the document’s assertions. See, e.g., Draft 

Endangerment TSD at 72 (noting major discrepancies that prevent establishment of confidence 

in the models). As stated above, EPA must not only note uncertainties but explain their 

implications by incorporating them into the Agency’s conclusions.

Finally, very little of this section of the Draft Endangerment TSD is specific to the United 

States. As described above, any CAA finding of endangerment must be tied to U.S. effects. 

Failure to identify adequately which of its conclusions apply to U.S. resources, and which do not,

renders the Draft Endangerment TSD inadequate as a resource for evaluating endangerment 

under the CAA.

3. Food Production and Agriculture

The part of the Draft Endangerment TSD addressing food production and agriculture is 

also affected by each of the flaws identified in the previous sections of these comments. As is 

true throughout the document, EPA in this part relies almost exclusively on reports of the IPCC 

and CCSP. This creates problems with respect to the geographic scope of the document’s 

analysis, and indeed, substantial portions of this section discuss global impacts and fail to 

distinguish adequately U.S. effects. Further, the limitations on the document’s sources of 

scientific information lead EPA to ignore significant new findings influencing projections for all 

of the major effects identified in this section, including temperature changes, precipitation, and 

invasive species impacts. See id. at 76-77, 79. Estimates of these effects should be revisited in 

light of newly available information. 
70

Further, this section of the TSD fails to quantify in any meaningful way the effects that it 

predicts, making a reasoned endangerment determination based on this information impossible. 

Similarly, despite acknowledging numerous beneficial effects in this area, the Draft 

Endangerment TSD rarely attempts to describe how positive and negative impacts may offset 

one another. See, e.g., id. at 80 (discussing benefits to and negative impacts on fisheries). In 

fact, the document appears to undertake this kind of analysis only where it asserts negative 

effects will outweigh positive effects. See, e.g., id. at 78 (discussing but downplaying benefits of 

direct CO2 exposure); id. (indicating that extreme events may offset any benefits of moderate 

climate change). This bias calls into question the remainder of this section’s analysis. Similarly, 

speculation in this section of the Draft Endangerment TSD undermines its reliability. 

Specifically, the Draft Endangerment TSD asserts that elevated CO2 levels can lead to reduced 

nutritional value by resulting in a decrease in C4 grasses and an increase in C3 grasses. It also 

states, however, that “the exact effects on both types of grasses and their nutritional quality still 

need[] to be determined.” Id. at 79. Accordingly, it is difficult to see how the Agency can 

predict negative outcomes given that, as its own document acknowledges, essential information 

is unknown.

Finally, in its discussion of drought, the Draft Endangerment TSD suggests that water 

shortages are a problem in certain regions of North America because of causes unrelated to

climate change. Id. at 79. It is unclear precisely why this information is included in a document 

intended to address potential climate change-related endangerment of public health or welfare. 

Indeed, to the extent any of the impacts that EPA discusses in this document cannot be attributed 

to GHG emissions and their effects, discussion of those impacts only undermines the usefulness 

of the scientific information in the document for any endangerment inquiry.
71

4. Forestry

This section of the Draft Endangerment TSD makes assertions regarding potential 

climate change-related effects on forest resources, including projections of increased forest 

growth, increased wildfires and drought, more frequent insect and disease outbreaks, more 

severe extreme-event disruptions, and reduced biodiversity resulting from the spread of invasive 

species.

Again, all of these projections must be reexamined in light of new scientific studies that 

require reassessment of previous modeling, with potential to substantially reconfigure

projections of climate change and related effects. 

Additionally, this section of the Draft Endangerment TSD notes a number of 

uncertainties in the scientific record but fails to explain their significance. See, e.g., id. at 81 

(noting that the combined effect of temperature increases, CO2 increases, nitrogen deposition, 

ozone, and forest disturbance on soil processes and carbon storage “remains unclear”). These 

limitations must be reflected in the conclusions presented. Further, this section of the Draft 

Endangerment TSD must avoid indulging in speculation in the face of uncertainties. For 

instance, the TSD cites as evidence for current climate change impacts that “[g]rowth is slowing 

in areas subject to drought.” Id. at 82. It is not established that this drought was caused by 

climate change or GHG emissions. Elsewhere, the document suggests that wildfires will pose 

the largest threat to forests over time. It notes, however, that wildfires and other extreme events 

are “not well represented in models” even as it suggests that wildfires will increase by as much 

as 10%. Id. at 83. Similar points can be made with respect to other assertions in this section of

the Draft Endangerment TSD.

This section of the Draft Endangerment TSD also continues to provide inadequate 

quantification of projected effects, limiting the ability to assess endangerment based on its 
72

analysis. Again, U.S. and global emissions and effects are not sufficiently delineated. In 

addition, the Draft Endangerment TSD states that forest productivity impacts due to climate 

change are “difficult to separate . . . from other potentially influencing factors, particularly 

because these interactions vary by location.” Id. at 81. This, however, is precisely the sort of 

information needed to evaluate the endangerment issue. Further, despite these acknowledged 

difficulties, the Draft Endangerment TSD asserts that certain observed changes, both negative 

and positive, are in fact due to climate change without providing support for that assertion. Id. 

Finally, this section of the Draft Endangerment TSD suggests that changing forestry 

conditions in the United States might place it at a competitive disadvantage with other nations 

that will experience more positive effects from climate change. The document does not, 

however, attempt to analyze this issue at any useful level of detail. Further, no other sections of 

the Draft Endangerment TSD address this issue. If, as seems likely, the United States is 

projected to be placed at a competitive advantage to other regions with respect to other potential 

effects of climate change, those possible benefits should also be reflected in the document. 

Failure to address these issues indicates a bias that EPA must address. Id. at 82-83.

5. Water Resources

This section of the Draft Endangerment TSD addresses a number of climate changerelated effects on U.S. water supply, water quality, and water uses. In general, these impacts 

must be reassessed in light of new scientific findings. Similarly problematic, this section, like 

the other “conclusion” sections of the Draft Endangerment TSD, fails to distinguish between 

global and U.S. effects, as is necessary to conduct an endangerment assessment. Id. at 87.

In addition to these more generally applicable flaws, this section of the Draft 

Endangerment TSD notes potential negative impacts on water quality and supply that are 

projected to result from population increases, id. at 86, but it does not tie these purported effects 
73

to climate change; such effects thus cannot properly be considered in assessing endangerment. 

This problem further muddies the document’s presentation of relevant scientific issues. 

Similarly, scientific clarity is compromised by this section’s treatment of various 

uncertainties and its tendency to engage in speculation. Specifically, the document 

acknowledges that data on existing groundwater supplies are “limited,” yet it goes on to make a 

number of assertions about groundwater impacts despite the lack of information. Id. at 88.

Additionally, this section of the document fails to note that modeling of extreme events is 

plagued by extreme uncertainties, even though this point is made in other sections. Id. at 90-91.

Finally, this section of the Draft Endangerment TSD fails to acknowledge and quantify 

clear beneficial effects even as it describes the negative effects associated with the source of such 

benefits. For instance, the Draft Endangerment TSD states that warmer water will result in 

transfer of pollutants from the water to the air and notes the negative impact on air quality. The 

document does not, however, attempt to quantify the benefit that this transfer will have on water 

quality or to compare the magnitude of this change to the other impacts on water quality 

discussed elsewhere in the document. Id. at 89. Similarly, the Draft Endangerment TSD notes 

that certain waters will likely experience increased navigability as a result of climate change, but

the document fails to quantify this benefit or to compare its relative value to decreases in 

navigability elsewhere. Id. at 91.

6. Sea Level Rise and Coastal Areas

This section of the Draft Endangerment TSD describes the impacts in U.S. coastal areas

of sea level rise projected to result from climate change. Id. at 92. It identifies a number of 

potential negative effects, including loss of salt marshes, coastal ecosystems, and the services 

and habitat that they provide. Id. at 92, 94. It also projects that sea level rise will result in 

increasing saltwater intrusion into drinking water supplies and freshwater resources, impacting 
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aquatic species. Id. at 94. It fails, however, to acknowledge the considerable uncertainties -- and 

their implications -- that plague this area of the science.

In addition to these impacts, however, this section of the Draft Endangerment TSD

discusses various impacts on and problems facing coastal areas that are not necessarily linked to 

climate change or even to sea level rise. See, e.g., id. at 92 (discussing coastal areas stressed by 

development and pollution); 93 (discussing “coastal squeeze” and its effects on wetlands), 93-94 

(discussing erosion in the Great Lakes where sea level rise “is not a concern”). These issues are 

improper for inclusion in an assessment of endangerment from GHGs and climate change; their 

inclusion tends to lead to a misleading overstatement of the impacts that should be considered in 

an analysis of whether endangerment exists.

7. Energy, Infrastructure, and Settlements

This section of the Draft Endangerment TSD describes the effects climate change may 

have on energy, infrastructure, and settlements. It contains a number of flaws that must be 

addressed in addition to the general need for reanalysis of projected climate change and its 

effects based on new scientific studies. 

This section of the Draft Endangerment TSD engages in speculation that is unsupported 

by the science and overstates the likely impact of climate change. For instance, the document 

acknowledges that industries and settlements “have become resilient to” variability in climate 

conditions but follows up this statement by suggesting that variability caused by climate change 

will be greater than capacity to adapt. Id. at 97. In the absence of evidence, the latter assertion is 

unwarranted. 

Similarly, this section of the document appears to favor unjustifiably study results that 

suggest impacts will be significant over those studies that predict the opposite. This is especially 

problematic in the document’s discussion of energy use for heating and cooling. The weight of 
75

the evidence on this issue indicates that overall energy use will not increase substantially because 

the changes will generally net each other out. Id. at 98. The Draft Endangerment TSD places 

considerable weight, however, on one study that predicts a significant increase in electricity 

demand, requiring substantial investment in new generation. There is no indication as to why 

this study warrants such deference. Indeed, the Draft Endangerment TSD does not even cite this 

study specifically, but refers only to a CCSP synthesis report that apparently references it. Id. In 

such a circumstance as this, where one study is given special weight, it is particularly 

unacceptable to fail to identify it with reasonable clarity. EPA must redress this problem and 

should, in general, provide more extensive citations to individual studies on which EPA relies. 

Further, the Agency must justify its decision to downplay the greater body of science on this 

issue, or else revise its statements to provide an objective analysis.

8. Ecosystems and Wildlife

The final section of the Draft Endangerment TSD’s discussion of specific impacts 

addresses ecosystem and species effects. Generally, it assesses impacts on ecosystem services, 

the effects of extreme events, and impacts on tourism and indigenous peoples. Id. at 104. In 

addition to the overarching concerns resulting from the need for reanalysis of earlier modeling 

results, this section must also be revised to redress a number of specific flaws.

Particularly problematic is that this section of the Draft Endangerment TSD places 

considerable emphasis on global impacts, especially regarding projected species loss, that are not 

relevant to an analysis of endangerment from GHG emissions and their resulting effects in the 

United States. Id. at 107. Further, the document states that there will be increases in the global

likelihood of extinctions and that 20% to 30% of species globally will be at risk. Id. The 

document notes, however, that such risk varies regionally from as low as 1%. Id. EPA fails to 
76

identify the risk levels applicable in the United States, a deficiency that, again, renders this 

information irrelevant to an endangerment assessment under the CAA.

This section of the document also engages in unfounded speculation. It cites, for 

instance, examples of greater species richness in areas that experienced less paleoclimatic 

changes as evidence that biodiversity is threatened by climate shifts. Id. There may be any 

number of explanations for such biodiversity differences, and, in any event, the document 

provides no scientific evidence for its proposition on this issue.

Finally, this section of the document includes information that is not clearly related to 

ecosystem services impacts. Specifically, the Draft Endangerment TSD discusses potential 

impacts on financial markets based on industries dependent on fisheries, timber, and tourism. Id. 

at 109. Similarly, this section’s discussion of the economic impacts of temporarily closing 

tourist areas does not appear to be clearly related to the projected species and ecosystem effects 

that it addresses and does not belong in this section. Id. at 110.

H. Conclusion

The Draft Endangerment TSD suffers from a number of serious flaws that undermine its 

reliability and render it unfit for use in making a CAA endangerment determination for GHG 

emissions.

First, EPA’s approach to analyzing these issues is hopelessly confused due to the 

Agency’s failure to define properly the scope of the analysis contained in the document. The 

CAA requires that EPA examine specific effects on U.S. public health and welfare. Instead, 

EPA discusses a mixture of U.S. and global effects that the Agency fails to associate with either 

U.S. or global emissions consistently or clearly. Further, it is unclear whether the Agency is 

addressing climate change related to anthropogenic GHG emissions, all GHG emissions, or other 

various sources. These flaws necessitate substantial reexamination and revision. 
77

Second, EPA has further undermined the usefulness of the Draft Endangerment TSD by 

relying almost exclusively on IPCC Assessments that do not address U.S.-specific effects. 

EPA’s attempt to attribute projected general North American effects to the United States 

introduces a host of uncertainties and ambiguities into the Agency’s analysis, and its attempt to 

justify such attribution is unsupported by the science. EPA must revise the Draft Endangerment 

TSD to incorporate information that is more relevant to effects on U.S. resources.

Third, EPA’s interpretation of the material contained in the scientific reports that it does 

cite is not consistently accurate. It overstates the conclusions that may be drawn, fails to resolve 

inconsistencies contained in the reports it cites, and occasionally appears to cite studies as the 

source of information that they do not actually contain. These inaccuracies and 

misrepresentations must be corrected. 

Fourth, the Draft Endangerment TSD fails to include in its assessment of the relevant 

science a number of significant new studies. These studies contradict specific statements and 

assertions in the Draft Endangerment TSD. Further, some of these studies significantly modify 

basic assumptions underlying, and thus demand reanalysis of, previously accepted modeling 

results. 

Fifth, the Draft Endangerment TSD fails to address adequately the numerous 

uncertainties present in the current science. In order to portray realistically the state of scientific 

knowledge, EPA must more effectively explain the implications of the uncertainties it identifies 

and be far more rigorous in identifying uncertainties throughout the document. 

Finally, the Draft Endangerment TSD exhibits significant biases through its failure to 

address fully all relevant issues, including the potential for positive effects associated with 

climate change. Further, the Agency has opted to ignore adaptation and mitigation in this 
78

document, despite the fact that such matters relate directly to the endangerment question. These 

biases must be removed.

In sum, the ostensible purpose of the Draft Endangerment TSD is to inform any

endangerment determination to be made by the EPA Administrator consistent with the provisions 

of the CAA. Failure to address the science in a thorough and balanced manner and to limit the 

document’s analysis to those issues relevant to EPA’s statutory authority has resulted in a 

document that overstates projected risks of climate change and that makes assertions that are not 

supported by available scientific information. Without substantial revision to correct its many 

deficiencies, the Draft Endangerment TSD cannot properly be used in any endangerment 

analysis.

VI. If EPA Decides To Propose Regulation of GHGs Under Any Existing Provision of 

the CAA, EPA Will Need To Consider Numerous Issues Further.

Section VI of the ANPR addresses issues related to the possibility of regulating GHGs 

from mobile sources under Title II of the CAA. 73 Fed. Reg. at 44432-76. Section VII of the 

ANPR discusses what EPA calls the “three major pathways that the CAA provides for regulating 

stationary sources” and additional stationary source authorities under the CAA that will be 

impacted by any future regulatory controls on emissions of GHGs under the Act. Id. at 44476/2-

3. The three major pathways are: (1) national ambient air quality standards (“NAAQS”) and 

state implementation plans (“SIPs”) under sections 107, 108, 109, and 110 of the Act; (2) 

performance standards for new and existing stationary sources under section 111 of the CAA; 

and (3) hazardous air pollutant standards under section 112 of the Act. In addition, section VII 

of the ANPR discusses the impact of regulatory controls on emissions of GHGs under the CAA 

on other important CAA programs including the PSD and Title V operating permit programs.
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UARG stresses that neither Title II of the CAA nor the “three major pathways” for 

stationary source regulation provides a suitable means for GHG regulation because none of these 

provisions of the CAA was designed to address air pollutants like GHGs. In considering whether 

to propose to regulate GHGs under the Act and under what section or sections to do so, EPA 

should consider the following important issues with regard to these sections.

A. Issues Relating to Possible Regulation of Mobile Sources Under Title II of the 

CAA

EPA’s ANPR addresses the potential regulatory options available to the Agency to 

regulate mobile sources under the authorities provided in Title II of the CAA. Specifically, these 

authorities apply to cars and light duty trucks; heavy duty trucks and buses; nonroad recreation 

vehicles; farm and construction machines; lawn and garden equipment; marine engines; aircraft; 

and locomotives. See id. at 44432/1-2. Although mobile source regulation is not a primary 

UARG concern, a number of issues raised in the ANPR do implicate UARG members’ interests. 

Accordingly, these comments address matters presented in Section VI of the ANPR that are 

relevant to the electric utility industry.

Briefly, these comments address several distinct categories of issues raised by EPA in its 

discussion of Title II authorities: (1) matters that implicate the relationship between mobile and 

stationary source regulation; (2) general legal issues raised in EPA’s Title II discussion; and (3) 

issues raised in the petitions seeking regulation of GHGs that are currently before EPA.

1. Issues Raised in EPA’s Title II Discussion that May Implicate 

Potential Regulation of Non-Mobile Sources

Many of the issues raised in Section VI of the ANPR are relevant only to mobile sources 

and are not specifically addressed in these comments. A number of matters raised by EPA, 

however, could affect potential regulation of electric generating facilities under the CAA. In 
80

particular, EPA has requested comment on two issues addressing how it might structure the 

relationship between potential mobile and non-mobile source regulation.

Specifically, EPA seeks comment on whether it should allow trading of emissions credits 

between mobile sources and other potentially regulated sectors if EPA ultimately proposes and 

promulgates a GHG regulatory program that incorporates cap-and-trade mechanisms. Id. at 

44433/1. Specifically, the Agency requests:

[P]ublic comment on the available authority for, and the merits of, allowing credit 

trading between mobile sources and non-mobile source sectors. One of the 

potential limitations of allowing credit trading only within the transportation 

sector is that it would not permit firms to take advantage of emission reduction 

opportunities available elsewhere in the economy. In particular, EPA requests 

comment on the advantages and disadvantages of allowing trading across sectors, 

and how to ensure that credit trading would have environmental integrity and that 

credits are real and permanent.

Id. at 44440/3. In general, EPA should make every effort to ensure that any regulation that it 

may devise achieves its policy goals while minimizing burdens on the regulated community.

Accordingly, to the extent that EPA is able to devise a legally sound cap-and-trade GHG 

regulatory program under the CAA, such program should accommodate trading across sectors. 

Such an approach would likely enhance the efficiency of any regulatory regime that EPA adopts, 

and the Agency should give serious consideration to its authority to implement such a program.

2. EPA’s Mobile Source Discussion Raises General Legal Issues That 

May Be Relevant to Other Potentially Regulated Sectors.

The section of the ANPR addressing EPA’s Title II authorities also addresses one issue of 

general legal significance that is relevant outside the Title II context. Specifically, EPA requests

comment on whether it may consider any global benefits of a proposed GHG regulation or 

instead is limited to consideration of domestic benefits in conducting its regulatory analysis. Id. 

at 44446/3. Economic analysis of regulatory actions is required by Executive Order 12866, 

“Regulatory Planning and Review.” This requirement is further governed by guidance issued by
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OMB, entitled “Economic Analysis of Federal Regulations Under Executive Order 12866,” (Jan. 

11, 1996) (“OMB’s Guidance”), available at http://www.whitehouse.gov/omb/inforeg/riaguide. 

html#ii. 

OMB’s Guidance addresses a number of issues, among them the consideration of 

international impacts in a regulatory cost-benefit analysis. Briefly, OMB’s Guidance requires 

EPA to focus on domestic costs and benefits and allows only for limited consideration of 

international impacts. Specifically, OMB notes that a proper cost-benefit analysis may consider 

effects on foreign resources only to the extent that a proposed regulation’s impacts on those 

resources would, in turn, result in domestic costs or benefits. This interpretation is supported by 

each of the examples OMB provides in the sections of its Guidance document addressing 

international considerations. For instance, OMB’s Guidance states that an agency must consider 

the cost to domestic companies of a proposed regulation that would require the purchase of 

specific equipment from a foreign manufacturer. See OMB’s Guidance at III.A.6. Further, 

OMB indicates that agencies will need to consider certain international trade implications of 

proposed regulations but only to the extent necessary to determine costs and benefits to the 

United States. Indeed, OMB’s Guidance illustrates this point by suggesting that agencies must 

consider the role of foreign competition in assessing the impacts of a regulation on domestic 

industry. Id. Finally, OMB’s Guidance states that special consideration must be given to costs 

and benefits of regulatory proposals that would have the effect of limiting imports. Again, 

OMB’s Guidance makes clear, however, that it is only the economic loss or benefit “to the 

United States” that agencies should consider. 

In sum, OMB’s cost-benefit analysis guidance does not indicate that it is generally

appropriate for agencies to consider foreign costs or benefits of U.S. regulations as a part of their
82

regulatory analysis. The governing Guidance instead indicates that international effects of 

regulatory action are relevant only to the extent that such effects result in domestic costs or 

benefits. Accordingly, EPA’s cost-benefit analysis of any regulatory proposal to address GHG 

emissions should consider only domestic impacts.

3. The Petitions Before EPA Raise Certain Issues that Are Relevant to 

the Utility Industry.

This section of the ANPR also addresses the seven petitions that EPA has received 

seeking regulation of GHGs under various provisions of Title II. Specifically, EPA has received 

petitions seeking GHG regulation under sections 211, 213, and 231 to address emissions from 

fuels, nonroad sources, and aircraft. See 73 Fed. Reg. at 44458/3. In addition to raising 

questions regarding EPA’s authority and the propriety of undertaking such regulation, these 

petitions address a number of issues of general relevance to other sectors that could be the 

subject of regulation under other CAA authorities. EPA requests comment on all of the issues 

raised by the petitioners. Id.

Generally, UARG disagrees with the legal analysis and conclusions contained in these 

petitions. These comments address the following issues: (1) the scientific claims made by 

petitioners and whether endangerment has been established; (2) whether an endangerment 

finding under one section of the CAA translates to an endangerment finding under other sections 

of the Act; (3) petitioners’ misinterpretations of Massachusetts v. EPA; and (4) assertions as to 

the extraterritorial application of the CAA.

First, each of the petitions on which EPA requests comment makes numerous scientific 

assertions regarding the effects of climate change. Briefly, these petitions claim that GHG 

emissions are now resulting and will continue to result in climate change-related public health 

and welfare impacts that negatively affect the petitioners, specific states, and the United States as 
83

a whole. These petitions generally conclude, without providing reasoned or thorough scientific 

analysis, that these effects will be “severe.” See, e.g., California v. Stephen Johnson, Petition for 

Rule Making Seeking the Regulation of Greenhouse Gas Emissions from Ocean-Going Vessels,

at 3 (Oct. 3, 2007). The petitions cite such purported effects as melting glaciers, rising sea 

levels, altered plant senescence, ocean acidification, proliferation of invasive species, droughts, 

floods, increased storm activity and intensity, decreasing water quality, heat waves, more 

frequent wildfires, decreases in air quality, threats to agricultural output, alteration of forest 

character, ecosystem and human infrastructure effects, and negative disease-related impacts. As 

support for these claims, the petitioners cite the Assessment Reports of the IPCC and a limited 

selection of individual scientific studies. See, e.g., California, et al. v. Stephen Johnson, Petition 

for Rule Making Seeking Regulation of Greenhouse Gas Emissions from Aircraft, at 2-11 (Dec. 

4, 2007); South Coast Air Quality Management District, Petition for Rulemaking Under the 

Clean Air Act to Reduce Global Warming Pollutants from Ships, at 2-4 (Jan. 10, 2008); 

California, et al., Petition for Rulemaking Seeking Regulation of Greenhouse Gas Emissions 

from Nonroad Vehicles and Engines, at 2-7 (Jan. 29, 2008); Friends of the Earth, et al., Petition 

for Rulemaking Under the Clean Air Act to Reduce the Emission of Air Pollutants from Aircraft 

that Contribute to Global Climate Change, at 5-6, 14-20 (Dec. 31, 2007). 

These purported effects and others not listed here are addressed in significant detail in

section V of these comments. Briefly, however, petitioners’ claims are unfounded and fail to 

take into account significant scientific uncertainties regarding the effects of climate change and 

the substantial amount of scientific information that contradicts the conclusions petitioners 

present. 
84

Further, the petitioners assert as to each source category for which they seek regulation 

that the contribution from these sectors is of sufficient size to require regulation. See, e.g., 

California v. Stephen Johnson, Petition for Rule Making Seeking the Regulation of Greenhouse 

Gas Emissions from Ocean-Going Vessels, at 6-7 (Oct. 3, 2007) (stating that percentage of 

ocean-going vessel contribution to GHG emissions renders it “a source that is vital to regulate”); 

see also South Coast Air Quality Management District, Petition for Rulemaking Under the Clean 

Air Act to Reduce Global Warming Pollutants from Ships, at 7 (Jan. 10, 2008) (stating that 

“ships emit 3% of the world’s greenhouse gases” and that such contribution is “significant”). 

Petitioners have not provided a scientific assessment supporting their claims that the proportion 

of emissions attributable to each of these sectors makes that sector a cognizable “contributor” to 

any endangering air pollution.

15 Indeed, some petitioners cite a statement in Massachusetts v. 

EPA discussing, for standing purposes, the contribution of the U.S. transportation sector as a 

whole in support of their assertion that an endangerment finding is required, despite the fact the 

Court explicitly neither made nor required any endangerment finding. Massachusetts, 127 S. Ct. 

at 1463 (“We need not and do not reach the question whether on remand EPA must make an 

endangerment finding. . . .”). Accordingly, petitioners’ claims that GHGs cause or contribute to 

air pollution that may reasonably be anticipated to endanger public health or welfare are

insufficiently supported and must be rejected. 

Second, some petitioners assert that an endangerment finding under one section of the 

CAA should essentially result in an automatic determination of endangerment under other 

15 It is noteworthy that petitioners do not uniformly address the percentage of emissions from 

these source categories that is specific to the U.S. portion of the relevant industry. EPA should 

be certain that it bases any endangerment determination only on the portion of such emissions 

that falls within its jurisdiction under the CAA.
85

sections of the statute. Specifically, petitioners seeking regulation of GHGs from nonroad 

vehicles and engines assert that an endangerment finding under section 202 of the CAA, which 

governs on-road motor vehicles, is sufficient to serve as a proxy for an endangerment 

determination under section 213. International Center for Technology Assessment v. Stephen 

Johnson, Petition for Rulemaking Seeking the Regulation of Greenhouse Gas Emissions from 

Nonroad Vehicles and Engines, at 8 (Jan. 29, 2008). Importantly, before regulation is authorized 

under section 213, EPA must “conduct a study of emissions from nonroad engines and nonroad 

vehicles ... to determine if such emissions cause, or significantly contribute to, air pollution 

which may reasonably be anticipated to endanger public health or welfare.” CAA § 213(a)(1) 

(emphasis added). Likewise, the section 202 endangerment standard requires EPA to determine 

if emissions of a given air pollutant from on-road motor vehicles and engines themselves cause 

or contribute to air pollution which may reasonably be anticipated to endanger public health or 

welfare. CAA § 202(a)(1); see also id. § 202(a)(3)(D). These standards are not interchangeable. 

Indeed, each provision addressing endangerment determinations must be viewed independently, 

and EPA must engage in a separate and appropriate endangerment analysis that addresses the 

pertinent source-specific standards contained in each relevant provision of the CAA. 

Third, petitioners make assertions regarding the meaning of the Supreme Court’s decision

in Massachusetts v. EPA that are incorrect and must be rejected by EPA. As stated above, some 

petitioners suggest that the Court’s assessment of the significance, for standing purposes, of the 

U.S. transportation sector’s contribution to GHG concentration levels is a de facto determination 

that mobile sources, even when further subdivided among source categories, are “significant” 

causes of or contributors to endangering air pollution. See, e.g., California v. Stephen Johnson, 

Petition for Rule Making Seeking the Regulation of Greenhouse Gas Emissions from Ocean-
86

Going Vessels, at 7 (Oct. 3, 2007). Again, this is a misinterpretation of the Supreme Court’s 

ruling. The Court’s statements on this point have no bearing on an endangerment determination, 

which involves a substantially different standard of scientific evidence and incorporates a degree 

of policymaking-related discretion not at issue in a standing analysis.

In addition, petitioners argue that the Court’s opinion in Massachusetts constrains the 

policy reasons the EPA Administrator may choose as support for a determination to decline to 

regulate GHGs under the CAA. See, e.g., California, et al., Petition for Rulemaking Seeking 

Regulation of Greenhouse Gas Emissions from Nonroad Vehicles and Engines, at 13 (Jan. 29, 

2008); California v. Stephen Johnson, Petition for Rule Making Seeking the Regulation of 

Greenhouse Gas Emissions from Ocean-Going Vessels, at 11-12 (Oct. 3, 2007). Indeed, the 

Court did reject certain policy reasons advanced by EPA for its decision to deny a petition for 

rulemaking under § 202 of the CAA, including foreign policy considerations and judgments as to 

the efficacy of the CAA as a regulatory tool. Massachusetts, 127 S. Ct. at 1462-63. The 

limitations of the Supreme Court’s decision, however, must be recognized. Its opinion addresses 

only regulation pursuant to section 202 and not other provisions of the CAA, including 

section 213, which the petitioners argue is subject to similar policy-related circumscriptions but 

which give EPA more discretion. See CAA § 213(a)(4) (EPA “may promulgate” regulations it 

“deems appropriate”) (emphasis added); 73 Fed. Reg. at 44433/3. This difference illustrates the 

critical point that EPA must carefully evaluate each relevant provision of the CAA to determine 

the extent of its discretion under that provision.

Finally, several petitioners assert that EPA has the authority to regulate foreign vessels 

and aircraft pursuant to sections 213 and 231, respectively. Petitioners arguing in favor of 

regulation of foreign ocean-going vessels argue that Congress intended that the CAA be applied 
87

extraterritorially. California v. Stephen Johnson, Petition for Rule Making Seeking the 

Regulation of Greenhouse Gas Emissions from Ocean-Going Vessels, at 13 (Oct. 3, 2007). As 

stated by the Supreme Court, “[i]t is a longstanding principle of American law ‘that legislation of

Congress, unless a contrary intent appears, is meant to apply only within the territorial

jurisdiction of the United States.’ This ‘canon of construction’ . . . serves to protect against 

unintended clashes between our laws and those of other nations which could result in 

international discord.” EEOC v. Arabian Am. Oil Co., 499 U.S. 244, 248 (1991) (quoting Foley 

Bros., Inc. v. Filardo, 336 U.S. 281, 285 (1949)). There is no clear indication that Congress 

intended the CAA to apply outside of U.S. territory.

16 Indeed, the only argument offered by 

petitioners in support of its contention is that the Americans with Disabilities Act (“ADA”), 42 

U.S.C. §§ 12101-12213 (1990), applies, in limited circumstances, to foreign flagged vessels. See

California v. Stephen Johnson, Petition for Rule Making Seeking the Regulation of Greenhouse 

Gas Emissions from Ocean-Going Vessels, at 13-14 (Oct. 3, 2007). The Supreme Court decision 

explaining this interpretation of the ADA, however, demonstrates that a clear statement of

congressional intent is required to give a general statute exterritorial application if the statute will 

affect the internal order of a foreign flagged ship. Spector v. Norwegian Cruise Line Ltd., 545 

U.S. 119, 125, 132, 134-35 (2005). Although the Court determined that the ADA contained such 

a statement of congressional intent, the text of the CAA contains no similar indication of 

16 One provision of the CAA authorizes consideration of the effects that air pollutants are 

expected to have on the public health or welfare of other nations to the extent that such foreign 

nations provide reciprocal rights. CAA § 115. This limited and clear expression of 

congressional intent does not, however, indicate that all CAA authorities also apply 

extraterritorially, and, in fact, suggests that Congress did not intend additional application of the 

CAA to foreign nations. See Keene Corp. v. United States, 508 U.S. 200, 208 (1993) (quoting 

Russello v. United States, 464 U.S. 16, 23 (1983)) (“[W]here Congress includes particular 

language in one section of a statute but omits it in another . . ., it is generally presumed that

Congress acts intentionally and purposely in the disparate inclusion or exclusion.”).
88

congressional intent. EPA appears to lack authority to apply the CAA in accordance with

petitioners’ request. At a minimum, EPA must conduct a thorough analysis of each CAA 

provision that might implicate these concerns and make a reasoned determination as to the extent 

of the Agency’s authority.

B. Issues Relating to Possible Regulation Through NAAQS and SIPs (CAA §§ 

107-110)

Section VII.A of the ANPR addresses issues relating to possible regulation of GHGs 

under sections 107 through 110 of the CAA. The discussion in this section of the ANPR 

highlights dramatically how ill-suited these provisions of the CAA are to any GHG regulation. 

As EPA acknowledges, “the ambient concentrations measured across all locations within the 

U.S. for purposes of comparison to the level of the standard would not vary, and all areas of the 

country would have the same designation -- that is, the entire U.S. would be designated either 

attainment or nonattainment, depending on the level of the NAAQS compared to observed GHG 

ambient concentrations.” 73 Fed. Reg. at 44480/1. This presents a whole host of problems for 

potential GHG regulation under these sections of the Act.

The heart of Congress’s design of the CAA is that states take the primary responsibility 

for ensuring that air quality within their borders meets the NAAQS. CAA §§ 107(a), 110(a); see 

also Clean Air Implementation Project v. EPA, 150 F.3d 1200, 1202 (D.C. Cir. 1998) (“The Act 

makes states primarily responsible for the attainment and maintenance of the NAAQS through 

state designed implementation plans. . . .”). States would have absolutely no control over 

whether they would attain a GHG NAAQS. As EPA notes, “[t]he SIP development process, 

because it relies in large part on individual states, is not designed to result in a uniform national 

program of emissions controls.” 73 Fed. Reg. at 44480/2. No action that a state could take on its 

own would be able to assist it in either attaining or maintaining a GHG NAAQS. Indeed, 
89

without international cooperation, no action that the United States takes could assure attainment 

or maintenance of a GHG NAAQS. That the entire United States would be either attainment or 

nonattainment for a GHG NAAQS, and that a state, in “implementing” such a NAAQS, would 

be unable to take any action to affect meaningfully the GHG “air quality” within its borders, 

demonstrate that no basis exists for any GHG NAAQS under the existing CAA.

Section 108(a)(1) of the CAA specifies three prerequisites for the listing of an air 

pollutant to be regulated by NAAQS. Specifically, this section provides that EPA:

[S]hall from time to time . . . list . . . each air pollutant --

(A) emissions of which, in [the Administrator’s] judgment, cause or contribute to 

air pollution which may reasonably be anticipated to endanger public health or 

welfare;

(B) the presence of which in the ambient air results from numerous or diverse 

mobile or stationary sources; and

(C) for which air quality criteria had not been issued before the date of enactment 

of the Clean Air Amendments of 1970, but for which [the Administrator] plans to 

issue air quality criteria under this section.

CAA § 108(a)(1) (quoted at 73 Fed. Reg. at 44477/1-2).

As discussed in more detail in sections IV and V of these comments, EPA has not yet 

made a determination whether GHG emissions endanger public health or welfare, which is the 

first prong of the section 108 test. Should EPA make such a determination with regard to 

another section of the CAA, such as section 202(a) regarding motor vehicles, that would not be 

dispositive with regard to section 108. Section 108 contains different language from that in 

section 202.

Unlike section 202(a), sections 108 and 109 authorize listing of a pollutant as a criteria 

air pollutant, and regulation of that pollutant through “national ambient air quality standards,” for 

the purpose of addressing any endangerment of the public health or welfare that may reasonably 
90

be anticipated due to the quantities of the pollutant in the ambient air, which is the relatively 

limited portion of the atmosphere to which the general public has access. CAA § 108(a)(2) (“Air 

quality criteria for an air pollutant [listed under section 108] shall accurately reflect the latest 

scientific knowledge useful in indicating the kind and extent of all identifiable effects on public 

health or welfare which may be expected from the presence of such pollutant in the ambient air, 

in varying quantities.”) (emphasis added); id. § 109(b)(2) (secondary NAAQS for a section 108-

listed air pollutant must be set at the level “requisite to protect the public welfare from any 

known or anticipated adverse effects associated with the presence of such air pollutant in the 

ambient air”) (emphasis added); 40 C.F.R. § 50.1(e) (“Ambient air means that portion of the 

atmosphere, external to buildings, to which the general public has access.”); Train v. NRDC, 421 

U.S. 60, 65 (1975) (“ambient air” is “the statute’s term for the outdoor air used by the general 

public”). In any proposed rule that EPA may develop on possible regulation of GHGs under 

these provisions of the Act, EPA will need to examine what the effect is on U.S. public health or

welfare due to the presence of GHGs in the ambient air in the United States. This may pose a 

serious obstacle to listing. It is far from clear, for example, that GHGs in the amount in which 

they are present in the ambient air in the United States could reasonably be anticipated to 

endanger public health or welfare. Thus, EPA will need to consider in any notice of proposed 

rulemaking how to differentiate the effects of GHGs due to their presence in the U.S. ambient air 

from the effects due to their presence in the rest of the global atmosphere. The absence of 

information supporting listing and regulation under sections 108 and 109 could, in fact, be the 

reason why the Administrator would conclude that he or she has no “plans to issue air quality 

criteria” for GHGs -- the third prerequisite for listing under section 108.
91

To use the third prerequisite in this fashion, however, EPA may well need to address 

whether and to what extent that prerequisite gives EPA discretion not to list a pollutant for which 

it has made an affirmative endangerment finding. EPA notes that the third prerequisite “could 

provide EPA discretion to decide whether to list those pollutants under section 108 for purposes 

of regulating them via the NAAQS.” 73 Fed. Reg. at 44477/2. In the 1970s, however, NRDC 

successfully argued to two federal courts that this language gave EPA no discretion to decline to 

list and regulate a pollutant under sections 108 and 109 where the Agency had conceded that the 

endangerment criterion (and the “numerous or diverse mobile or stationary sources” criterion in 

section 108(a)(1)(B)) was satisfied for that pollutant. That litigation culminated in the decision 

of the U.S. Court of Appeals for the Second Circuit in NRDC v. Train, 545 F.2d 320 (2d Cir. 

1976), aff’g, 411 F. Supp. 864 (S.D.N.Y. 1976), that EPA must list and regulate a pollutant under 

sections 108 and 109 when it has made an endangerment finding for that pollutant, 

notwithstanding the “plans to issue air quality criteria” provision in section 108(a)(1)(C). EPA 

correctly notes the existence of this case in the ANPR and notes that because it was decided 

before the Supreme Court’s decision in Chevron v. NRDC, 467 U.S. 837 (1984), the Agency may 

have an argument that its original interpretation of the statute should now be accorded deference. 

73 Fed. Reg. at 44477 n.229.

The interpretation that the third criterion does not provide EPA with discretion regarding 

whether to list an air pollutant for which an endangerment finding has been made was raised as

recently as 2003 when three states (Connecticut, Maine, and Massachusetts) premised a 2003 

citizen suit against the Administrator on that 1976 decision. Massachusetts v. Horinko, No. 

3:03-CV-984 (D. Conn. filed June 4, 2003) (dismissed without prejudice by plaintiffs on 

September 3, 2003, in light of EPA’s denial of the rulemaking petition that led to Massachusetts 
92

v. EPA). More recently, national environmental group representatives -- as part of their attempt 

to blunt opposition to their campaign for GHG regulation under sections 202 and 111 -- have 

suggested that the “plans to issue air quality criteria” clause does give EPA discretion not to list 

and regulate, but they have not explained their legal rationale for abandoning the position 

advanced by NRDC and adopted by two courts. See, e.g., Strengths and Weaknesses of 

Regulating Greenhouse Gas Emissions Using Existing Clean Air Act Authorities: Hearing 

Before the House Energy and Commerce Subcommittee on Energy and Air Quality, 110th Cong. 

(Apr. 10, 2008), Testimony of Lisa Heinzerling, Professor of Law, Georgetown University Law 

Center, at 6 (noting that the third prerequisite “may provide the Administrator somewhat more 

wiggle room in deciding whether to issue a NAAQS for a greenhouse gas, even after an

endangerment finding); Massachusetts v. EPA Part II: Implications of the Supreme Court 

Decision: Hearing Before the House Select Committee on Energy Independence and Global 

Warming, 110th Cong. (Mar. 13, 2008), Testimony of David Bookbinder, Chief Climate Counsel, 

Sierra Club, at 9 (“Bookbinder Testimony”) (noting that the third prerequisite “appears to 

contemplate some discretion on EPA’s part in whether to establish a NAAQS”). There are, in 

UARG’s view, compelling reasons to believe that that position was and is incorrect, but in any 

event, EPA should state clearly and comprehensively its view of the matter -- specifically 

including its interpretation of the current effect of NRDC v. Train -- before it proceeds with any 

proposed rule that addresses, or that arguably could give rise to, regulation of GHGs under 

section 108 and 109.

EPA notes that section 108 also requires EPA to issue “air quality criteria” once a 

pollutant has been listed. In response to this requirement, EPA issues “criteria documents” or, as 

they have been called more recently, “integrated science assessments,” for each of the pollutants 
93

listed under section 108. These documents are reviewed by EPA’s Clean Air Scientific Advisory 

Committee and, as noted above, must “accurately reflect the latest scientific knowledge useful in 

indicating the kind and extent of all identifiable effects on public health or welfare which may be 

expected from the presence of such pollutant in the ambient air, in varying quantities.” CAA § 

108(a)(2). EPA specifically asks whether it would be “appropriate” for the Agency to rely on the 

most recent reports of the IPCC and the synthesis reports of the CCSP “as an important source or 

as the primary basis for the Agency’s issuance of ‘air quality criteria.’” 73 Fed. Reg. at 44477/3.

For the numerous reasons discussed in more detail in section V.B. of these comments, 

reliance on the IPCC and CCSP reports for this purpose, without any independent analyses by 

EPA of the latest relevant scientific knowledge, would not be appropriate and would not comply 

with the requirements of the CAA. Moreover, as stated by the Agency throughout its most 

recently completed criteria document, the Integrated Science Assessment for Sulfur Oxides --

Health Criteria, Integrated Science Assessment for Sulfur Oxides -- Health Criteria, EPA/600/R08/047F (Sept. 2008) (“SOx ISA”), EPA has established a number of basic standards governing 

preparation of these scientific analyses that would conflict with reliance on the IPCC and CCSP. 

First, EPA has generally established that to accurately reflect the latest scientific knowledge, air 

quality criteria must consist of EPA analysis of recent, individual scientific studies that have 

been subject to peer review. SOx ISA at 1-2. To ensure the timeliness of the research analyzed 

in the SOx ISA, EPA engaged a call for information from the public and its own “ongoing 

literature search process that includes extensive computer database mining on specific topics.” 

Id. Additionally, the Agency indicated that “[a]ll relevant epidemiologic, human clinical, and 

animal toxicological studies ... published since the last review were considered.” Id. Indeed, at 

times, EPA has even altered its own self-imposed study publishing cut-off dates to include 
94

especially important research in its air quality criteria analysis. See, e.g., Air Quality Criteria for 

Particulate Matter, EPA/600/P-99/002aF at I-iii (Oct. 2004) (indicating that the Agency 

expanded its original limitations on study publication date to accommodate analysis of 

“important new studies published through 2003”) (hereinafter “PM AQCD”). Failure to conduct 

a similar literature search and analysis of the most recent information would not only be 

inconsistent with basic principles of sound science but would also with past EPA practice.

Similarly, through its preparation of past air quality criteria, EPA has established study 

selection standards that emphasize the science that is most relevant to the establishment of 

NAAQS, a concern not reflected in IPCC or CCSP reports. For instance, in the SOx ISA, EPA 

placed considerable emphasis on those studies “conducted in the U.S. or Canada [as opposed to]

those from other geographic regions.” SOx ISA at A-2; see also id. at 1-1 (“The Integrated 

Science Assessment (ISA) is a concise review, synthesis, and evaluation of the most policyrelevant science, and communicates critical science judgments relevant to the NAAQS review.”) 

(emphasis added). Further, criteria documents are drafted in response to specific “policyrelevant questions that provide a framework for [the] review of the scientific evidence.” Id. at 1-

1 (emphasis added). Other criteria documents have emphasized the importance of “substantial 

external peer and public review” and “iterative reviews of successive drafts” of the air quality 

criteria prepared by EPA. See, e.g., PM AQCD at 1-12; see also id. at 1-16 (“The assessment 

presented in this document is framed by: (1) the selection of pertinent issues to be addressed; (2) 

the selection of relevant studies and an approach to the presentation of information drawn from 

those studies; and (3) the selection of an approach to interpreting and integrating the body of 

evidence evaluated in the document.”). None of these crucial components to NAAQS-specific 
95

scientific assessment can be achieved through adoption of the reports of the IPCC and CCSP as 

the statutory air quality criteria.

The analysis and conclusions of the IPCC primarily concern global effects and emissions. 

The purpose of a criteria document is to examine the latest scientific evidence regarding the 

effect that atmospheric concentrations of a criteria air pollutant have on public health and welfare

in the U.S. due to its presence in the U.S. ambient air. The IPCC reports do not focus on the

effects in the U.S. of the presence of GHGs in the U.S. ambient air. The closest the IPCC gets to 

examining the United States is a short discussion of projected effects of climate change in North 

America, and it is not scientifically justifiable to read conclusions with regard to North America 

as generally applying to the United States. In the event EPA were to list GHGs (or a subset of 

GHGs) as a criteria air pollutant under section 108, it could not avoid its obligation to “issue air 

quality criteria” that “accurately reflect the latest scientific knowledge useful in indicating the 

kind and extent of all identifiable effects on public health or welfare which may be expected 

from the presence of such pollutant in the ambient air, in varying quantities.” CAA § 108(a)(2).

Moreover, any criteria document would need to address the beneficial effects of GHGs in the 

ambient air. American Trucking, 175 F.3d at 1051-53.

Because EPA cannot substitute the IPCC or CCSP reports for the criteria document, in 

the event EPA decides to establish a NAAQS for GHGs, it should wait to list GHGs (either as a 

group or individually) until it has made significant progress on both the air quality criteria and a 

proposed NAAQS. As the Agency acknowledges, preparation of air quality criteria and 

revisions to a proposed NAAQS can take several years even when the pollutant at issue has long 

been listed and regulated as a criteria pollutant, and EPA expects that preparation of a criteria 

document for GHGs would be particularly burdensome because of the complexity of climate 
96

change science and the vast amount of research that would be relevant. 73 Fed. Reg. at 44483/2-

3. Once EPA lists a pollutant under section 108, however, EPA must issue a criteria document 

and proposed NAAQS within twelve months, followed by a final NAAQS 90 days after that. 

CAA §§ 108(b)(2), 109(a)(1), (2). When criteria pollutants were first listed before enactment of

the 1970 Clean Air Act, considerable work had already been done on criteria documents that 

made this schedule feasible. 73 Fed. Reg. at 44483/2.

Although EPA does not have discretion with regard to timing once it lists an air pollutant 

under section 108, it does have discretion with regard to the timing of the listing itself, as the 

Agency correctly notes. Id. To avoid a situation where due care cannot be taken to consider the 

science fully and what the “requisite” level of any NAAQS should be, in the event EPA decides 

to list a GHG as a criteria air pollutant under section 108, it should wait to list until after it has 

completed most of its work on the air quality criteria. This would be important to ensure that the 

Administrator has all of the relevant scientific information to determine at what specific level 

any NAAQS for GHGs would be “‘requisite’ -- that is not lower or higher than is necessary -- to 

protect the public health with an adequate margin of safety” or the “public welfare from any 

known or anticipated adverse effects associated with the presence of such air pollutant in the 

ambient air.” Whitman, 531 U.S. at 475-76; CAA § 109(b)(1), (2).

With regard to the setting of NAAQS, EPA specifically notes that in its view it has 

discretion to set either a primary or a secondary standard for a pollutant. 73 Fed. Reg. at 

44478/2. EPA notes that it revoked the secondary standard for carbon monoxide after a review 

of the scientific evidence indicated that there was no evidence of adverse welfare effects from 

the presence of carbon monoxide in the ambient air. Id. This does not answer the question, 

however, of whether the CAA authorizes EPA to establish a secondary standard for an air 
97

pollutant without a primary standard. UARG agrees with EPA that any possible public health

effects from the presence of GHGs in the ambient air are the result of indirect effects from 

“ecological and meteorological changes, which are effects on welfare,” and that it might not have 

the scientific evidence needed to establish a primary standard for GHGs. Id. Because of the lack 

of scientific evidence regarding direct effects of GHGs on public health, EPA discusses the 

possibility of setting only a secondary NAAQS for GHGs to address welfare effects. Should 

EPA decide to follow that course of action, it would need to discuss its legal authority for setting 

a secondary standard without a primary standard. 

EPA notes that it has precedent for listing related compounds as a group rather than 

individually and has done so with nitrogen oxides and particulate matter. Id. at 44477/2. EPA 

discusses the fact that listing each GHG separately would present “significant challenges” for 

determining which level is appropriate because “the science of global climate change is generally 

focused on the total radiative impact of the combined concentration of GHGs in the atmosphere.” 

Id. at 44479/2. Because the level that would be required to protect public health and welfare for 

any individual GHG is highly dependent on the concentration of other GHGs in the atmosphere, 

setting individual levels presents challenges. Id. In the event EPA decides to use section 108 of 

the Act, UARG generally supports listing GHGs as a group, if at all, but only if endangerment 

and other applicable statutory criteria have been satisfied for all of the gases to be regulated. 

UARG emphasizes that any CAA program to regulate GHGs would need to encompass sources 

of all GHGs and not only sources of CO2.

17

17 Moreover, if EPA decides to regulate GHGs as a group under the Act, UARG supports 

measuring these GHGs using a common denominator, such as CO2-equivalent.
98

C. Issues Relating to Possible Regulation Through Performance Standards for 

New and Existing Stationary Sources (CAA § 111)

Notwithstanding EPA’s statements that the ANPR does not represent an Agency policy 

decision, it appears from its discussion of new source performance standard (“NSPS”) authority 

that EPA believes that CAA section 111 in its current form may provide the most appropriate 

authority and flexibility to regulate GHG emissions from stationary sources under the CAA, 

including through a broad cap-and-trade program.18 For that reason, it is particularly important 

that EPA carefully consider the many factors discussed below that suggest that section 111 is not 

an effective program for GHG regulation. Indeed, regulation under the existing section 111 

would impose significant costs on companies and consumers at a time of great financial 

uncertainty without a clear health or environmental benefit.

As described below, and in response to the many issues raised by EPA in the ANPR, 

UARG does not believe section 111 is an appropriate mechanism for regulating GHG emissions. 

Moreover, regulation of GHG emissions under section 111 generally would not meet the policy 

design criteria set forth in the ANPR. In particular, using NSPS authority would require long, 

expensive, and complex category-by-category regulatory development that would be 

significantly limited by the technologies available for emission reductions. In addition, section 

111 regulation could greatly overburden the Agency and states by requiring regulation of a large 

segment of economic actors without a real environmental benefit. Such regulation also may not 

18 If EPA decides to propose to regulate GHGs through a cap-and-trade program, it needs to 

address and solicit public comment on whether it is the appropriate federal agency to administer 

such a program. The size of a cap-and-trade program for GHGs would be enormous and would 

dwarf the size of any of EPA’s existing trading programs. It might be more appropriate for 

another federal agency with more expertise in commodities markets -- such as the U.S. 

Commodity Futures Trading Commission -- to manage and administer a GHG market.
99

necessarily support an effective and broadly-based cap-and-trade program, further increasing 

costs to regulated industries and consumers. 

Should EPA nevertheless decide to propose GHG regulations under section 111, it must 

be careful to do so in an even-handed manner and not overburden the electric power sector 

simply because more information is known about emissions from that sector and (arguably) 

potential emission reduction opportunities for that sector than for some other significant 

contributors. Moreover, any section 111 standard should not disproportionately burden smaller 

electricity generating units, which constitute a significant element of the nation’s power 

generation supply. 

1. Authority To Regulate

At the outset, it must be stressed that an affirmative endangerment determination under 

CAA section 202(a)(1) neither requires regulation under section 111 nor makes regulation under 

it inevitable. Section 111 establishes an endangerment criterion for new categories of stationary

sources of pollutants and in this respect, therefore, differs significantly from CAA section 

202(a)(1) and other relevant CAA sections that address regulation of pollutants. Under section 

111, the Administrator may revise a list of categories of stationary sources and “shall include a 

category of sources in such list if in his judgment it causes, or contributes significantly to, air 

pollution which may reasonably be anticipated to endanger public health or welfare.” CAA § 

111(b)(1)(A) (emphasis added).

Section 111 thus differs from section 202(a)(1) and other CAA sections because it 

addresses categories of sources, not pollutants. Moreover, it provides EPA with significant 

discretion as to whether or not to list a source category. In addition, it requires that the category

of sources “significantly” contributes to endangering air pollution. Perhaps most important, for 

source categories that are already listed under section 111, EPA has broad discretion to decide 
100

whether or not to adopt standards for additional pollutants. See, e.g., 73 Fed. Reg. 35838, 

35858/3-35859/1 (June 24, 2008) (preamble to final rule on petroleum refineries NSPS). 

Therefore, should EPA determine that GHGs meet the section 202(a)(1) endangerment test, this 

would not require EPA automatically to list new categories of sources of GHGs, or to add 

standards for GHGs, under section 111.19 Moreover, should EPA decide to list new categories of 

sources of GHGs under section 111(b), it would need to show that such categories 

“significantly” contribute to air pollution that endangers public health or welfare.

Moreover, the endangerment language cited above is directly relevant only to new, 

reconstructed, and modified sources. Many large sources of GHG emissions, e.g., fossil fuelfired steam generators, industrial-commercial-institutional steam generating units, municipal 

waste combusters, Portland cement plants, and petroleum refineries, are already subject to 

section 111 standards for conventional pollutants. EPA can set standards for “new” pollutants

(i.e., pollutants that generally are not otherwise regulated under the CAA) at existing sources, but 

only indirectly, by publishing “emissions guidelines.” Following publication of such guidelines, 

these existing sources are regulated pursuant to state plans that set performance standards that

take into consideration, among other factors, “the remaining useful life of the existing source.” 

CAA § 111(d)(1). As a result, GHG emissions may be treated very differently under section 

111, depending on whether they are emitted from categories of new stationary sources or 

existing sources.

At the same time, regulation of GHGs from a new or existing source may very well 

render GHGs “subject to regulation” under the CAA, and thus require GHGs to be considered in 

19 Should EPA nonetheless decide to propose to regulate GHGs under section 111, UARG would 

urge EPA to consider adding a broader set of new categories to lessen the burden on the electric 

power sector and other listed categories. 
101

a Best Available Control Technology (“BACT”) analysis for any PSD permit, regardless of the

type of source to which the permit would apply. Therefore, regulation of one or more sources of 

GHGs under section 111 may result in piecemeal and inconsistent regulation of emitting 

industries yet require all major new sources of GHG emissions to undergo PSD determinations. 

73 Fed. Reg. at 44492/3. This ad hoc, disjointed approach to regulation could significantly 

undercut any cost savings EPA would seek to achieve through market-based mechanisms under 

section 111.

2. Efficacy

EPA rightly points out that section 111 differs from other CAA provisions in that, when 

EPA determines under section 111 to list and regulate a category of sources (or set a design, 

equipment, work practice, or operational standard), it must consider the cost of achieving 

emission reductions along with any non-air quality health and environmental impacts and energy 

requirements, CAA § 111(a), (h), -- a range of factors beyond harm to public health or welfare. 

In addition, section 111 includes considerations of “efficacy.” Under section 111(b)(1)(B), EPA

in general is to review new-source standards of performance at least every eight years, and shall 

revise them “if appropriate,” but need not review a standard (much less revise it) if it determines 

that “such review is not appropriate in light of readily available information on the efficacy of 

such standard.” In other words, where EPA has already set standards for a category of sources, 

such as electric utility steam generating units, it is not required to review or revise the standards

or to add standards for new pollutants for that source category if it does not consider such actions 

to be efficacious.20

20 EPA has taken the position in response to comments on its final NSPS rules for petroleum 

refineries and for Portland cement manufacturers developed under the eight-year review 

provision that it is not required by section 111(b) to promulgate a new standard of performance 

(continued...)
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3. Policy Design Criteria

According to EPA, it should consider potential sources of regulation based on specific 

policy design criteria set forth in the ANPR. 73 Fed. Reg. at 44491/2. Regulation of GHGs 

under section 111 would meet few, if any, of these criteria. 

a. Effectiveness of Health and Environmental Risk Reduction

GHG emissions in the United States occur from a number of types of sources, including

sources in the transportation, residential, commercial, and industrial sectors. Id. at 44402-03. 

Even within a given sector, emissions occur from a combination of large and small sources. 

Moreover, the perceived threat to human health and the environment is from global emissions. 

Thus, it is difficult to determine whether reductions from emissions from any one sector in the 

United States would be effective in risk reduction. Section 111 regulation, however, does not 

allow regulatory decisions by sector but by source category. This makes it very difficult, if not 

impossible, to determine whether a performance standard for a specific source category will 

really be effective in reducing any public health or welfare risks that may be associated with 

collective emissions. Moreover, as discussed below, it might be difficult to set a standard 

appropriate for all sources in even one sector, given cost and technology considerations. For 

example, small electric steam generating units make up an important part of the U.S. power 

sector but may warrant different standards or limits than larger sources, possibly complicating 

efforts to determine whether NSPS regulation would even be effective for the power industry. 

for an air pollutant not already covered by a standard of performance under review. See 73 Fed. 

at 35859/1-2; 73 Fed. Reg. 34072, 34084/2-3 (June 16, 2008). Rather, the Agency has discretion 

to decide whether to do so. 73 Fed. Reg. at 35858-60; 73 Fed. Reg. at 34084/2-3. UARG agrees 

that EPA has discretion as to whether to include GHGs in a standard of performance.
103

EPA would likely have to subcategorize steam generating units and set different NSPS for 

different sizes and fossil fuels as well as distinguish between new and existing units.

b. Certainty and Transparency of Results

Similarly, given the category-by-category nature of regulation under section 111,

differences in emissions levels among differently sized and differently configured sources, and 

the global distribution of GHGs, it would be difficult to determine whether standards for a given 

source or category -- or even a number of categories -- would reduce national or global GHG 

emissions, let alone reduce any health or environmental risk in the United States. 

c. Cost Effectiveness and Economic Efficiency

This is a particularly important criterion because cost, efficacy, technological availability,

environmental impact, and energy requirements are all statutory factors that EPA must consider

under section 111. Cost-effectiveness and efficiency are particularly important factors to 

consider given the current economic climate and financial troubles facing consumers and 

industry.

d. Equity Considerations

Regulation of GHGs under section 111 would raise equity concerns because section 111 

regulation is based on specific source categories and is not comprehensive across all economic 

sectors that emit GHGs. In fact, in the ANPR, EPA asks whether section 111 would allow EPA 

to regulate GHGs only from certain source categories for which it has adequate information on 

emissions and reduction opportunities or for which control technologies may be available. This 

picking and choosing of source categories could result in the inequitable imposition of costly 

controls on one sector (or even on one category) while other sectors or categories would not be 

so regulated. Moreover, any regulations that significantly raise electricity costs would have a 
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disproportionate impact on consumers at lower income levels and could drive some industrial 

operations to foreign countries, leading to job losses. 

e. Policy Flexibility Over Time

Although section 111 regulation gives EPA some flexibility to address sources differently 

through subcategorization, EPA also appears to recognize the limitations inherent in the NSPS 

approach, under which “stretch goals” may not be appropriate and control technologies must be 

adequately demonstrated. In addition, serious questions have been raised by environmental 

groups and some states as to whether section 111 is an appropriate statutory vehicle for a broadbased cap-and-trade system. 

f. Incentives for Innovation and Technology Development

As is discussed below and as EPA acknowledges, section 111 does not lend itself to 

imposition of “technology-forcing” regulations due to requirements that technology be 

demonstrated and available and that standards be “achievable.”

g. Pro-Competitiveness

EPA could create international competitiveness issues by establishing costly standards for 

certain categories of sources that are not regulated similarly outside the United States. 

Moreover, EPA could conceivably create domestic competitiveness issues between and among 

sectors, such as between large and small sources that have different technological and financial 

capabilities, between categories of sources, and between sectors. Indeed, the very flexibility that 

EPA perceives in section 111 to prioritize and differentiate among source categories can lead to 

competitiveness issues. Because existing-source regulations are imposed through state plans, a 

possibility also exists of creating competitiveness issues among states and regions. 
105

h. Administrative Feasibility

Although EPA may be able to administer NSPS for GHG emissions from certain source

categories with adequate monitoring and reporting capacity, it would not be able to address the 

full scope of GHG emissions from all significant sectors without establishing tailored standards 

or measures for all such sectors. These efforts could quickly overwhelm the capacity of the 

Agency (as well as some of the sources). Moreover, EPA must consider the administrative 

burdens on states, which would be the primary implementers of standards for existing sources (in 

addition to the burdens on states and facilities resulting from the fact that section 111 regulation 

would trigger PSD and Title V obligations for GHGs). States face increasing burdens on their 

resources, and state-to-state administration may vary considerably. 

i. Enforceability

To a large extent, enforcement is a function of ease of administration, monitoring, 

reporting, and inspection. As with administrative feasibility, EPA may be able to enforce NSPS 

adequately for some categories of sources but may find it difficult to do so for other source 

categories or certain sources within categories. Moreover, enforcement of standards for existing 

sources would be a state responsibility as an initial matter, and enforcement may vary

considerably among states, especially considering reductions in state administrative and 

enforcement resources in an economic downturn.

j. Avoidance of Unintended Consequences

As under other CAA sections, regulation of GHGs from even one source category under 

section 111 could be expected to make all major sources of GHGs subject to PSD and Title V 

requirements for GHGs. 73 Fed. Reg. at 44492/3. Thus, even if EPA should decide to regulate 

only one or a few source categories to simplify administration of the NSPS program, it may find 

itself overwhelmed by permitting requirements under the PSD and Title V programs. As 
106

discussed above, category-by-category regulation may cause differential costs and burdens 

among sources, while increasing costs to consumers at a time of great financial uncertainty.

Moreover, some may argue that any mandated increases in efficiency may trigger NSR

requirements for existing units on the theory that more efficient equipment would be able to run 

longer, raising the potential for enforcement actions and citizen suits. NSR could, in turn, 

significantly affect costs and timing for facilities trying to meet efficiency-based standards. 

Finally, achieving lower emissions of conventional pollutants, such as NOx and SO2, can give 

rise to significant ancillary power (“parasitic energy”) needs to operate pollution control 

equipment, potentially leading to more, not fewer, GHG emissions. 

4. New and Existing Sources

EPA asks in the ANPR whether, if section 111 standards were set for GHGs from 

specific source categories, those standards should differ between new and existing sources. If, 

notwithstanding the concerns described above about the appropriateness of section 111 

regulation at all, EPA proposes regulations under section 111, it should treat new and existing 

sources differently. Under section 111, standards of performance for both new and existing 

sources share several common criteria, including the requirement that section 111 standards be 

established considering costs and energy requirements. These common criteria, however, will 

often result in different considerations for new and existing sources. In most cases, it would be 

more costly and energy-intensive to impose emission limits that would require retrofits at 

existing sources to meet emission standards than to require that new sources meet limits with

emission control technology. For example, supercritical design boilers may be possible with 

new units for certain types of facilities, but completely impractical as a retrofit option. 

Differences in costs and energy requirements can also affect any resulting environmental 

benefits.
107

Significantly, section 111(d) recognizes the differences between new and existing sources 

by including, as an additional criterion for existing sources, the “remaining useful life of the 

existing source to which [the] standard applies.” CAA § 111(d)(1); see also id. § 111(d)(2). 

Thus, any proposed section 111 standard for existing sources would have to be developed with 

consideration for how that standard could be met by sources with varying useful lives. This is 

particularly important for energy efficiency standards because a given source’s efficiency tends 

to diminish over its useful life, and investments that may be economical for a newer source may 

be inappropriate for an older source near the end of its useful life. 

5. Definition of Source Categories and Coverage of Sources

Section 111 gives EPA considerable discretion in distinguishing among classes, types,

and sizes within categories of new sources for the purpose of establishing NSPS. CAA 

§ 111(b)(2). The ANPR lists as relevant factors the magnitude of GHG emissions from a source 

category, the potency of particular GHGs emitted, whether emissions are continuous, seasonal,

or intermittent, what information is known about that category’s emissions, and whether 

regulating those emissions would be beneficial. 73 Fed. Reg. at 44487/3. EPA then inquires 

whether, given such discretion, it should develop sub- or super-categories of sources or set 

standards to be met plant-wide, facility-wide, or company-wide. It also asks whether it should 

set standards for all GHGs or for emissions of specific GHGs such as CO2. Finally, EPA 

considers whether it has the discretion to set priorities among sources and categories, regulating 

some but not others based on such factors as available information on emissions, cost, and 

availability of reduction technologies. Id. at 44488/2-3, 44490/3.

As an initial matter, UARG believes that any such discretion, where it exists, should be 

exercised in accordance with principles of fairness. Nothing in the CAA requires EPA to set 

NSPS for GHG emissions from new, reconstructed, or modified sources simply because it makes 
108

an affirmative endangerment finding under another CAA provision. But if EPA decides to set an

NSPS for GHGs, it should be careful to do so in a way that does not penalize a sector for 

providing data to EPA and should be careful not to do so simply because more is known about 

that sector than others. This is a particular concern for the electric utility generating sector, 

which has long been required to report CO2 emissions and which is subject to comprehensive 

regulation of conventional pollutant emissions. EPA should not succumb to the temptation to 

focus any regulatory efforts only on one sector in order to avoid difficult decisions with respect 

to other sectors; if it proposes GHG standards for any source categories, it should propose how it 

will address other significant emitters of GHGs as well, regardless of whether it may be 

relatively more difficult or costly to achieve reductions from those sources.

If EPA proposes regulating GHGs under section 111, it should seek to provide sources 

with maximum flexibility to meet any standards or requirements, including, where appropriate,

through subcategorization of sources that could take into account differences among the 

capacities of various types of sources. On the other hand, super-categories, especially those 

envisaged by EPA in the ANPR may simply be too broad to apply in a meaningful way.21

Facility-wide, plant-wide, and company-wide standards would provide valuable flexibility but

also complexity in trying to integrate such standards into potential economy-wide programs like 

trading. Such standards also might be challenged by environmental organizations as not 

authorized by the CAA. The important criteria for EPA to consider are achievement of costeffective emission reductions, energy requirements, and other relevant factors, including equity 

21 Super-categories, into which many types of sources are combined, may also unfairly skew a 

finding that a source category meets the “significance” factor in section 111(b)(1)(A). In 

addition, life-cycle approaches, as suggested in the ANPR, would be hard to administer, 

measure, and enforce.
109

in relation to other sectors. These criteria should apply to any regulatory option that EPA may 

decide to propose.

6. Best Demonstrated Technology

a. Technological Availability

EPA claims that “[t]he systems, and corresponding emission rates, need not be actually in 

use or achieved in practice at potentially regulated sources or even at a commercial scale” and 

that, “if a technology is ‘adequately demonstrated’ for use at a date in the future, EPA could 

establish a future-year standard based on that technology.” 73 Fed. Reg. at 44487/1. EPA fails 

to show that either the CAA or case law supports these assertions. Under section 111, EPA is to 

set NSPS at a level that “reflects the degree of emission limitation achievable through the 

application of the ‘best system of emission reduction’ which [taking into account the cost of 

achieving such reduction and any nonair quality health and environmental impact and energy 

requirements] . . . has been ‘adequately demonstrated.’” Id. at 44368/1 (quoting CAA § 

111(a)(1)(A)). This standard is commonly referred to as “Best Demonstrated Technology” or 

“BDT.” Section 111 “most reasonably seems to require that EPA identify the emission levels 

that are ‘achievable’ with ‘adequately demonstrated technology.’ After EPA makes this 

determination, it must exercise its discretion to choose an achievable emission level which 

represents the best balance of economic, environmental, and energy considerations.” Sierra 

Club v. Costle, 657 F.2d 298, 330 (D.C. Cir. 1981). 

But, under section 111, it is not enough that “the system . . . be adequately 

demonstrated.” Essex Chem. Corp. v. Ruckelshaus, 486 F.2d 427, 433 (D.C. Cir. 1973). Rather,

the standard that is set based on BDT must also be “achievable.” Id. (emphasis added); see also 

Portland Cement Ass’n v. Ruckelshaus, 486 F.2d 375, 391 (D.C. Cir. 1973) (“Section 111 looks 

toward what may fairly be projected for the regulated future, rather than the state of the art at 
110

present, since it is addressed to standards for new plants. . . . It is the ‘achievability’ of the 

proposed standard that is in issue.” Thus, the technology on which the standard is based must 

not be a matter of speculation or conjecture, cf. Nat’l Asphalt, 539 F.2d at 787 (finding that EPA 

had adequate factual basis for standards), and the technology must not be “uncertain and 

unproven,” Sierra Club, 657 F.2d at 346-47 (“The statutory factors which EPA must weigh are 

broadly defined and include within their ambit subfactors such as technological innovation, [but] 

. . . [t]his is not to say . . . that NSPS may be relaxed just to accommodate an uncertain and 

unproven technology.”).

The U.S. Court of Appeals for the D.C. Circuit has exclusive jurisdiction to review NSPS 

and has examined section 111 standards on numerous occasions. See, e.g., Nat’l Lime Ass’n v. 

EPA, 627 F.2d 416 (D.C. Cir. 1980); Nat’l Asphalt, 539 F.2d at 775; Essex Chem., 486 F.2d at

427; Portland Cement, 486 F.2d at 375. The D.C. Circuit has established a rigorous standard of 

review. The court, for example, has remanded section 111 standards where the agency had 

“legitimate problems with the methodology of . . . tests” on which EPA relied in setting the 

standards, Portland Cement, 486 F.2d at 392, and in light of the limited relevance and reliability 

of those tests, id. at 396, 401. For the standards to be upheld, the record must support their

“achievability.” 

Thus, according to the D.C. Circuit, the CAA: 

[D]oes [not] allow the EPA to set the standards solely on the basis of its 

subjective understanding of the problem or “crystal ball inquiry.” See Portland 

Cement, . . ., 486 F.2d 391. An adequately demonstrated system is one which has 

been shown to be reasonably reliable, reasonably efficient, and which can 

reasonably be expected to serve the interests of pollution control without 

becoming exorbitantly costly in an economic or environmental way. An 

achievable standard is one which is within the realm of the adequately 

demonstrated system’s efficiency and which, while not at a level that is purely 

theoretical or experimental, need not necessarily be routinely achieved within the 

industry prior to its adoption. 
111

Essex Chem., 486 F.2d at 433-34 (footnote omitted). The D.C. Circuit in National Lime

later defined “achievable” as denoting “a uniform standard [that] must be capable of being met 

under most adverse conditions which can reasonably be expected to recur and which are not or 

cannot be taken into account in determining the ‘costs’ of compliance.” Nat’l Lime, 627 F.2d at 

431 n.46.

EPA’s claim in the ANPR that it could establish a future-year standard based on 

“adequately demonstrated” technology that is not actually in use or achieved in practice must 

contend with the fact that, “[a]lthough it is conceivable that a particular control technique could 

be considered both an emerging technology and an adequately demonstrated technology, there is 

inherent tension between the two concepts.” Sierra Club, 657 F.2d at 341 n.157. In light of the

novelty of any emerging technology, it inevitably would be harder for EPA to acquire the 

necessary information about that technology than it would to support a standard based on 

established technologies. Thus, if EPA were to propose a “future-year” standard that is not 

based on technology in current commercial use, it would have great difficulty justifying that 

proposal in light of the section 111 factors. 

The ANPR language discussed above simply does not account properly for the 

requirement that any section 111 standard must be achievable through an adequately 

demonstrated system of emission reduction. It also does not account properly for the role of 

EPA’s periodic review of NSPS. Because section 111(b)(1)(B) of the CAA requires EPA to 

review NSPS periodically, the Agency does not even arguably have a need to establish “future” 

standards at this time based on a “crystal ball inquiry” but may undertake new rulemaking, where 

appropriate and justified, to review the NSPS when a previously inadequately demonstrated 

technology has matured to a degree that its capabilities can fairly be assessed. Accordingly, if 
112

EPA does not have enough information regarding available demonstrated technologies to 

propose a standard, it should wait until such information exists to do so; it should not propose or 

establish standards based on what technology it estimates might become available in the future.22

b. Technological Availability in the Power Sector

The ANPR and EPA’s draft Technical Support Document on Stationary Sources (“Draft 

Stationary Source TSD”) make certain assumptions about what technology may be available to 

achieve emissions reductions at sources in various sectors in the near and longer term, including 

the electric power sector and coal-fired power plants in particular. For existing facilities, EPA 

acknowledges that flexibility for new technologies is limited and instead identifies a number of 

ways plants can increase their efficiencies through “well known” modifications and upgrades to 

plant systems suggesting, for example, that net heat rate reductions (improvements) of up to 10%

may be feasible through various efficiency improvements. 73 Fed. Reg. at 44488/1, 44492/1; 

Draft Stationary Source TSD at 16-18. EPA states that these options are well known in the 

industry “but for many reasons are not equally feasible from plant to plant or from unit to unit in 

a plant” and that combined cycle and simple cycle combustion turbine units “have fewer physical 

options for significant efficiency improvement.” Draft Stationary Source TSD at 16. Thus, EPA 

effectively acknowledges that establishing sector-wide performance standards for existing 

sources in the power sector would be difficult and clearly would involve different considerations 

than would establishing standards for new sources, and that BDT may not be available for all 

sources in a category. 

22 EPA asks whether it should or must set unit-specific requirements for categories of sources 

under section 111 in addition to any cap-and-trade system. 73 Fed. Reg. at 44490 n.247. To the 

extent that EPA proposes such standards for categories of sources as an independent 

requirement, the compliance costs would significantly undermine the cost savings EPA might 

estimate from use of a cap-and-trade system.
113

As to new sources, EPA observes that as older plants are retired, their capacity could be 

replaced with new, more efficient units such as those with supercritical coal plant design, which 

may produce 10% to 15% lower GHG emissions than the average existing coal plant per British 

thermal unit for the same amount of electricity that is produced. According to EPA, future, more 

advanced ultra-supercritical plant designs with efficiencies of about 40% would have heat rates 

that are 18% below the current coal fleet average and produce much lower GHG emissions than 

the average existing coal plant. Id. at 16, 17.23

Many of EPA’s assumptions are based on a limited deployment of supercritical plants 

with comparatively high thermal performance that may be beyond the abilities of the many 

smaller sources that make up an important portion of U.S. electric power production, especially

in rural areas. For example, a DOE report addressing new pulverized coal-generation options 

reports that subcritical pulverized coal-fired units are typified by full-load gross plant thermal 

efficiencies of 37.6% (and may be able to extract approximately 38% to 39% gross thermal 

efficiency).

24 Some units that have recently been permitted in the U.S. achieve efficiencies by 

adopting super-critical and ultra-critical steam condition, but most higher-performing new plants 

have been deployed on a limited basis in Europe and Japan. Even at new plants, the highest 

gross thermal efficiencies that can be achieved will degrade by 2 to 3 percentage points over the 

load range; thus, a plant full-load gross thermal efficiency of 39% may relax to a load-weighted

gross thermal efficiency of 36% to 37%. EPA should also recognize the role of variability in 

23 EPA also briefly discusses biomass co-firing as a potential substitute for coal in existing and 

future coal-fired boilers. Although biomass can reduce GHG emissions, it still produces 

significant amounts of those emissions. Moreover, its usefulness at plants, particularly large 

coal-fired plants, is acknowledged to be limited due to supply and operational constraints. Draft 

Stationary Source TSD at 17. 

24 U.S. Department of Energy, Market-Based Advanced Coal Power Systems, DOE/FE-0400 at

3.1-6 (1999).
114

determining gross thermal efficiency and the need to account for such variability in setting any 

NSPS based on such efficiencies.

In addition, efficiencies of new plants inevitably degrade over their lifetimes.

Historically, the aging of equipment and compromise in tolerances of the steam turbine will 

degrade efficiency over time. That factor brings down the gross thermal efficiency of a 

subcritical boiler design over an entire plant lifetime to 36%, which would presumably lower the 

lifetime estimates of efficiencies in higher thermal performance technologies. In addition,

whereas high thermal efficiency technologies for new units have been used in a limited number 

of plants around the world, mandating such efficiency in an NSPS could eliminate or severely 

restrict the role of smaller generating units (i.e., less than 200 megawatts) that are key to the 

portfolios of smaller public power and municipal agencies. This is a critical problem because 

NSPS must be broadly achievable by sources and applications in a given regulated sector. 

Finally, EPA asks whether section 111 might allow for “technology-forcing” 

requirements, a subject discussed above. The technology forcing concept might apply to 

expectations of refinements and improvements in the pollution control capacity of a technology

that is already well demonstrated, as opposed to a regulatory “leap of faith” that a technology

that is not demonstrated today will eventually prove to be a viable technology within some time 

certain. For example, it may be rational for EPA to project that selective catalytic reduction 

could achieve 88% NOx reductions some years in the future if it has determined that that 

technology can currently reduce NOx by 86%. But unless a technology is currently viable, any 

assessments of the cost of achieving any emissions standard premised on that technology would 

rest on speculation would, thus, be impermissible.
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c. Carbon Capture and Sequestration

EPA also seeks information as to whether CCS technologies are adequately demonstrated 

to be available in the electric power and other sectors. 73 Fed. Reg. at 44492/1-2. Although 

CCS may indeed hold promise for mitigation of GHG emissions in the future, it is not currently 

available or ready for large-scale and rapid deployment. At the current time, it has not been 

adequately demonstrated on the necessary scale and is not presently available to most sources, 

and thus cannot be relied on in a section 111 context to achieve necessary reductions either at

existing or at new or modified sources.

Numerous impediments exist to wide-scale application of CCS technology, especially in 

the power sector. For example, in a recent study, the U.S. Government Accountability Office 

(“GAO”) found that key technological barriers include a lack of experience in capturing 

significant amounts of CO2 from commercial-scale power plants and the significant costs of 

retrofitting existing plants.25 GAO found that, to date, there have been only small-scale tests of 

CO2 capture at power plants around the world, and these projects typically remove CO2 from 

only a small fraction of the power plant’s overall output; “CO2 capture has not been 

demonstrated on a large scale at a power plant in the United States or in any country.” GAO 

25 GAO Report, Climate Change, Federal Actions Will Greatly Affect the Viability of Carbon 

Capture and Storage As a Key Mitigation Option, Report to the Chairman on the Select 

Committee on Energy Independence and Global Warming, House of Representatives, GAO-08-

1080 (Sept. 2008) (“GAO Report”). In particular, GAO noted that the challenges to CCS 

deployment include: “(1) the absence of any commercial-scale demonstration of the technology

at a power plant; (2) certain limitations of coal gasification technology for capturing CO2

emissions at new power plants; and (3) the high cost of retrofitting CCS to existing pulverized 

coal-fired power plants that will, for the next several decades, account for a significant share of 

U.S. CO2 emissions.” GAO Report at 16; see also World Resources Institute, CCS Guidelines: 

Guidelines for Carbon Dioxide Capture, Transport, and Storage at 34 (2008) (discussing high 

costs of retrofit relative to costs for new plants, as well as facility space limitations and other 

factors that make retrofit difficult); id. at 35 (noting that CCS technologies have not been proven 

on a commercial scale).
116

Report at 17. Further, the IPCC found in its special report on CCS that “there have been no 

applications [of carbon capture] at large-scale power plants of several hundred megawatts.”26

Indeed, DOE, the International Energy Administration, and others have recommended 

accelerating the development of full-scale CCS demonstration projects for this very reason.27

Finally, parasitic energy costs associated with using CCS technology are substantial.

There are further technological barriers to the availability of CCS technology. Integrated 

Gasification Combined Cycle (“IGCC”) technology combined with CCS is seen by some as 

promising for new plants because CCS costs are thought to be lower at IGCC plants than at 

pulverized coal-fired plants. There are impediments, however, to deployment of IGCC 

technology with CCS, including the large costs of construction, reliability concerns, and 

challenges to building new plants in the United States. Moreover, the GAO Report concludes 

that “[k]ey assessments indicate that post-combustion capture of CO2, which would be used at 

26 IPCC, Special Report on Carbon Dioxide Capture and Storage at 107 (2005). The GAO 

Report does conclude that carbon capture technology has been demonstrated at plants that purify 

natural gas and produce chemicals, and some of the captured CO2 at those plants is used in 

enhanced oil recovery, while the remainder is vented. GAO Report at 17 & n.15. According to 

the GAO Report, there are technological barriers to direct adaptation of CCS technologies from 

the natural gas purification process to coal-fired power plants, and CCS in the natural gas 

processing industry would account for a very small percentage of GHG emissions per year from 

large stationary sources. Id. at 18.

27 GEO reported that the National Coal Council noted that CCS “‘deployment will require 

successful pilot-scale testing and operation at a demonstration scale of 50 to 100 megawatts

before companies will have confidence in their cost and performance for large scale systems.’” 

GAO Report at 16; see also Union of Concerned Scientists, Coal Power in a Warming World; A 

Sensible Transition To Cleaner Energy Options, Exec. Summ. at 1-2 (Oct. 2008) (“UCS 

Report”) (“CCS is still an emerging technology. It has the potential to substantially reduce CO2

emissions from coal plants, but it also faces many challenges. In its current form the technology

would greatly increase the cost of building and running coal plants while greatly reducing their 

power output. . . . For CCS to play a major role in reducing CO2 emissions, an enormous new 

infrastructure must be constructed to capture, process, and transport large quantities of CO2. 

And although CCS has been the subject of considerable research and analysis, it has yet to be 

demonstrated in the form of commercial-scale, fully integrated projects at coal-fired power 

plants.”). 
117

pulverized-coal power plants, faces significant technical challenges that greatly affect the cost 

and feasibility of its deployment using currently available technology.” Id. at 22.28

Beyond technological and cost limitations, there are regulatory and legal uncertainties 

that serve as significant barriers to the availability of CCS, including legal uncertainty regarding 

liability for potential CO2 leakage and ownership of the CO2 once it is injected. Id. at 15, 23-26; 

see also World Resources Institute, Capturing King Coal: Deploying Carbon Capture and 

Storage Systems in the US at Scale at 24 (2008); UCS Report, Exec. Summ. at 1 (observing that 

“the development of regulatory standards and mechanisms to guide this process[] will be needed 

to minimize the environmental risks associated with CO2 leakage (including groundwater 

contamination)”). These uncertainties are seen as presenting significant financial barriers to 

further development and deployment.29 Consequently, for many reasons, CCS technology could 

not be considered adequately demonstrated or available as BDT at this time for section 111

standards for the power sector or for most other major GHG-emitting sectors. Moreover, given 

its cost and complexity, CCS would not be appropriate for the multitude of smaller sources of 

GHG emissions. 

28 The GAO Report identifies such challenges as the need to treat large volumes of flue gas to 

remove CO2, the need to remove impurities from the flue gas before CO2 removal, the large 

amount of energy needed to compress the captured or separated CO2, and the significant cost 

increases in retrofitting CCS to an existing plant. As to the last factor, an IPCC assessment 

concluded that retrofitting a CO2 capture system to existing coal-fired power plants would 

increase the incremental cost of producing electricity from about 150% to 290%. GAO Report at 

22-23.

29 See e.g., CCS Alliance, “Study of Legal Issues Relating to Risk and Liability in Connection 

with Carbon Capture and Storage” (July 23, 2008), available at http://www.ccsalliance.net; C. 

Trabucchi & L. Patton, Storing Carbon: Options for Liability Risk Management, Financial 

Responsibility, Daily Environment Report, Vol. 2008 no. 170 (Sept. 3, 2008) (proposing a design 

for addressing the financial risk arising from deployment of CCS technology).
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7. Market Mechanisms

EPA opines that section 111 as it currently exists can provide statutory authority for a 

comprehensive cap-and-trade program for GHG emissions because such a program meets the 

three criteria for “standard of performance” set out in section 111(a), namely that such a program 

would constitute (1) “a standard for emissions of air pollutants,” that (2) “reflects the degree of 

emission limitation achievable,” and (3) does so “through the application of the best system of 

emission reduction” that “has been adequately demonstrated.” 73 Fed. Reg. at 44491/2; see 

CAA § 111(a)(1). There are several reasons for believing that questions likely would be raised 

as to whether a proposed cap-and-trade program under section 111 actually would satisfy those 

criteria.

First, section 111, as noted above, authorizes regulation by category of sources and not 

by pollutant. It is not practical to set, administer, and enforce NSPS for every source of GHG 

emissions in the United States, and EPA, should it decide to propose regulations for GHG 

emissions under the CAA, will certainly look to the major sources of those emissions. If it does 

regulate, EPA may be able to create an industry-specific cap-and-trade program in which only 

some categories of sources and sectors could participate, but that approach would undercut one 

of the presumptive main goals of any broad-based cap-and-trade regime -- to maximize 

emissions reductions and spread the costs across the economy so that no one industry, or its 

customers, is disproportionately burdened.

Second, assuming that GHGs are not listed as criteria pollutants or regulated under 

section 112, promulgation of NSPS for GHGs would also trigger regulation under section 111(d)

for existing sources. But regulation of existing sources is a state function, albeit one based on 

EPA guidelines. The Agency itself recognizes the need for compatible state rules “promoted” by

EPA rules and guidance if such a broad cap-and-trade program were to be possible under section 
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111. 73 Fed. Reg. at 44487/2. This may be very difficult to achieve in practice as states may 

choose different regulatory approaches and might not be required to join, or to coordinate their 

programs with, a national trading program. Indeed, under the now-invalidated Clean Air 

Mercury Rule (“CAMR”), which was based on section 111 authority and sought to create a capand-trade program for mercury emissions, several states declined to implement the model capand-trade program that EPA had adopted. 

Third, environmental organizations have raised significant questions as to whether 

section 111 can provide the legal basis for a trading program. When EPA used section 111 to 

establish a cap-and-trade program for mercury under CAMR, it was strongly opposed by those 

organizations, arguing that a trading program that allowed some sources to purchase emission 

allowances and not reduce their own emissions did not constitute a “standard of performance”

within the meaning of section 111 because, in their view, it did not constitute “a requirement of 

continuous emission reduction, including any requirement relating to the operation or 

maintenance of a source to assure continuous emission reduction.” CAA § 302(l) (emphasis 

added) (defining “standard of performance”). These groups further argued that, under section 

111(d), each source had to achieve continuous emission reductions and that sections 111(a) and 

(d) required state plans under section 111(d) to reduce emissions from any and all existing 

sources covered by those plans. 

Finally, these groups argued that EPA would be prevented from instituting a trading 

program under section 111 by application of ASARCO Inc. v. EPA, 578 F.2d 319 (D.C. Cir. 

1978), which rejected a proposed form of emissions trading under section 111 because, among 

other things, it allowed operators to “avoid installing the best pollution control technology” and 

thereby “postpone[d] the time when the best technology must be employed.” Id. at 327-328. 
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The environmental groups argued that section 111 is meant to apply uniformly to new and 

modified sources, regardless of their location. See Final Opening Brief of Environmental 

Petitioners, New Jersey v. EPA, No. 05-1097, at 26-29 (D.C. Cir. final form brief filed July 23, 

2007). Although the D.C. Circuit to date has had no occasion to resolve the merits of this 

argument, one cannot conclude that such an argument would not be made to challenge the legal 

basis of any section 111 cap-and-trade program for GHG emissions.

8. Updating Information and Standards

EPA solicits comment on whether and how often it should revise standards and require 

and review information from sources under section 111. 73 Fed. Reg. at 44489/2-3. UARG 

understands that global climate change is a long-term issue with an evolving body of science and 

data, and that technologies change over time, so that regulatory programs must have the 

flexibility to adapt. Although section 111 does provide EPA with authority to revise NSPS

periodically, it is not required to do so, and in fact, need not review (or revise) them if it is “not 

appropriate in light of readily available information on the efficacy of [the] standard.” CAA § 

111(b)(1)(B). If EPA decides to propose to regulate GHGs under section 111, it should ensure 

that any policy it follows on requiring submission of information and on revising standard fairly 

and appropriately balances the need to reflect significant new circumstances with sources’ need 

for long-term planning and certainty, and it should not impose unnecessarily onerous reporting 

and information requirements. For example, the Agency should not constantly update standards 

but do so only when substantial developments occur in new and available technologies.

D. Issues Relating to Possible Regulation of GHGs as Hazardous Air Pollutants

(CAA § 112)

Section 112 is the third “main regulatory pathway” identified by EPA for possible 

regulation of stationary sources under the CAA. EPA must list for regulation all categories of
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major sources that emit one or more of the hazardous air pollutants (“HAPs”) listed under 

section 112. If it decided to regulate GHGs under section 112, EPA would first need to add 

GHGs to the list of HAPs and then would need to regulate GHG emissions from all major 

sources of GHG emissions. A source is considered “major” under section 112 when it emits or 

has the potential to emit 10 tons per year or more of any one HAP or 25 tons per year of any 

combination of HAPs. CAA § 112(a)(1). For many of the reasons identified by EPA, regulation 

of GHGs under section 112 would be problematic.

As EPA notes, regulation under section 112 would result in EPA having to regulate a 

very large number of new and existing stationary sources, including small GHG emitters, 

because of the low 10 and 25 ton per year thresholds. Unlike section 111, section 112 does not 

give EPA discretion to limit regulation to those sources that contribute “significantly” to air 

pollution endangering public health and welfare. 73 Fed. Reg. at 44494/2-3. EPA is right to be 

concerned that a large number of small sources would be required to comply if GHG regulation 

occurred under section 112. Given the section 112 thresholds, a large family residence that has 

all natural gas appliances would have to comply with GHG regulation. Id. at 44495/1.

On the other hand, one aspect of regulation under section 112 is that pollutants regulated 

under that section are exempt from regulation under the PSD program. CAA § 112(b)(6). In 

addition, a section 111 standard for existing sources also cannot be established to regulate 

emissions of a listed HAP that are regulated under section 112. Id. § 111(d)(1)(A)(i). Any 

usefulness that these exemptions may provide, however, are outweighed by the disadvantages of 

regulation under section 112. For example, although regulation under the PSD program would 

be precluded by regulation under section 112, the problem that the PSD program presents with 

regard to the sheer numbers of covered sources would only be magnified under section 112. The 
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thresholds for the PSD program are 100 or 250 tons per year of a GHG. As discussed above, the 

thresholds for regulation under section 112 are much lower -- 10 or 25 tons per year. Thus, far 

from decreasing the number of sources that would have to comply with GHG regulation, 

regulation under section 112 would be expected to increase that number exponentially

In addition, EPA would have little flexibility with regard to the timing of any controls for 

GHGs as listed HAPs under section 112. EPA says that, under section 112, it generally would 

have to adopt maximum achievable control technology (“MACT”) requirements for newly listed

source categories within two years after it lists the source category. 73 Fed. Reg. at 44494/3. As 

EPA notes, MACT standards are more complicated to set than standards under section 111; and 

meeting a two-year deadline for developing a MACT standard would be difficult; and these short 

timelines would not allow time for emerging GHG technologies to be further developed. See id.

at 44494/3, 44495/2

Another aspect to regulation under section 112 is that regulation under section 112 might

preclude regulation of GHGs under the NAAQS program of sections 108 and 109. As EPA 

acknowledges, however, although it is clear that regulation of an air pollutant under section 108 

generally precludes regulation of that pollutant under section 112, it is much less clear that the 

converse is true. Id. at 44495/2. If EPA should decide to propose regulation under section 112, 

it will need to explore further whether a basis exists for concluding that doing so would preclude 

regulation under section 108.

EPA also notes that a significant impediment to any GHG regulation under section 112 is 

that, in EPA’s view, that section does not provide it with the flexibility to use a market-based 

approach to GHG regulation, which could mean that any regulation of GHGs under section 112

would be even more costly, and less cost-effective. Id. at 44495/1. 
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It is important to note, however, that although this point may apply generally, it may not 

apply to electric utility steam generating units. Electric utility steam generating units are subject 

to a specific provision of section 112 -- section 112(n)(1) -- which provides EPA with more 

flexibility for this source category than section 112 does for other categories. Section 112(n)(1) 

is the exclusive regulatory authority under which section 112 for this source category. As 

UARG explained in its comments on EPA’s proposed CAMR, UARG believes that section 

112(n)(1)(A) provides EPA with authority to adopt a cap-and-trade program for electric utility 

steam generating units. See Comments of the Utility Air Regulatory Group on the Proposed 

National Emission Standard for Hazardous Air Pollutants; and, in the Alternative, Proposed 

Standards of Performance for New and Existing Stationary Sources: Electric Utility Steam

Generating Units, Docket ID No. OAR-2002-0056 (June 29, 2004), at 120-39. Section 112(n)(1) 

establishes an additional distinction with respect to any regulation under section 112 of 

emissions from electric utility steam generating units. Specifically, regulation of those units 

under section 112(n)(1) can be based only on public health reasons; effects on public welfare are 

not considered in determining whether to regulate this source category under section 112. CAA 

§ 112(n)(1)(A). As EPA acknowledges, and as these comments discuss above, any public health 

effects from GHG emissions are far from scientifically certain and in any event are not direct 

effects. See 73 Fed. Reg. at 44478/2.

E. Implications for the PSD Program from Possible Regulation of GHGs Under 

the CAA

The potential for regulation of GHGs under the PSD program presents an enormous 

challenge for EPA and the nation. The CAA requires owners and operators of major stationary

sources of air pollution to obtain construction permits before building or modifying those 

sources. PSD applies in areas that are in attainment with the NAAQS. Nonattainment NSR 
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(“NNSR”) applies in nonattainment areas and generally is more stringent than PSD.30 Id. at

44497/2. Although PSD primarily applies to criteria air pollutants for which a NAAQS has been 

established, PSD can also apply to CAA-regulated pollutants for which there is no NAAQS. It 

does not apply to HAPs listed under section 112 or to section 211(o). At the present time, EPA 

believes -- and UARG agrees -- that PSD does not currently apply to GHGs.31 Id. at 44497/3. If 

EPA decided to propose and promulgate a rule establishing limits on emissions of GHGs from 

mobile sources or stationary sources, PSD permits would need to contain an emissions limit for 

those GHGs that reflects BACT. BACT is “defined as the maximum achievable degree of 

emissions reduction for a given pollutant (determined by the permitting authority on a case-bycase basis), taking into account energy, environmental, and economic impacts.” Id.

Under the PSD program, a PSD permit is required for the construction or modification of 

any major stationary source that emits or has the potential to emit 250 tons per year of a 

regulated pollutant (100 tons per year for a source in listed categories, including large fossil fuelfired steam electric plants); the threshold in nonattainment areas for NNSR generally is 100 tons 

per year. Id. at 44498/2-3. Because many sources emit CO2, EPA anticipates that “many types 

of new small fuel-combusting equipment could become newly subject to the PSD program if 

30 If EPA decided to propose and promulgate a NAAQS for GHGs that resulted in the country 

being deemed nonattainment, then NNSR would apply throughout the United States. This would 

result, among other things, in new and modified sources having to offset their GHG emissions 

and meeting the Lowest Achievable Emission Rate (“LAER”) instead of BACT. 73 Fed. Reg. at 

44498/2. LAER does not allow consideration of costs or energy and environmental impacts of 

emissions control technology. Id. at 44502/2. Because the ANPR primarily discusses PSD, not 

NNSR, UARG’s comments do the same.

31 Note that environmental groups, led by Sierra Club, have argued in numerous permit 

proceedings that PSD does in fact now apply to CO2 emissions. EPA’s Environmental Appeals 

Board recently held that because the language of the CAA is ambiguous on this issue, EPA has 

discretion to provide a reasonable interpretation of that language. In re: Deseret Power Elec. 

Coop., PSD Appeal No. 07-03 (EPA Envtl. Appeals Board Nov. 13, 2008).
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CO2 becomes a regulated . . . pollutant.” Id. at 44498/3. Additionally, for sources already 

considered major sources, such as fossil fuel fired power plants, regulation of CO2 likely would 

create the risk that many more changes would arguably be deemed major modifications. See id.

at 44499/1. As an example, EPA notes that a hypothetical 500 megawatt electric utility boiler 

that burns bituminous coal and that is well controlled for traditional air pollutants can emit more 

than 580 tons per hour of CO2. At such a source, any change that otherwise qualifies as a 

modification triggers NSR under applicable regulations and results in just 10 additional minutes 

of utilization over the course of a year could result in a 100-ton-per-year increase, and thus could 

potentially become subject to PSD requirements. See id.

EPA currently estimates that approximately 200-300 PSD permits are issued nationally 

each year for construction of new sources and major modifications at existing sources. If CO2

were to become a regulated pollutant, EPA estimates that the number of PSD permits required to 

be issued each year would increase by more than a factor of 10 (i.e., more than 2000 to 3000 

permits each year). Id. at 44499/1-2. UARG believes, however, that this is actually an 

underestimate. EPA’s estimate does not account for a source’s potential to emit year-round but 

is based on actual emissions, and if year-round operation is assumed to be a source’s potential to 

emit, EPA’s “estimates would likely be an order of magnitude higher.” Id. at 44504/2. EPA’s 

sole reliance on actual emissions is misplaced, as EPA’s rules make clear that a source’s 

potential to emit applies in the case of brand new construction and for modifications where the 

existing facility has not begun normal operations. 40 C.F.R. § 52.21(b)(21).

UARG agrees with EPA that regulation of CO2 through the PSD program “would be a 

very inefficient way to address the challenges of climate change.” 73 Fed. Reg. at 44501/3. To 

determine if it is possible to avoid the extraordinary administrative and regulatory burdens that 
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this regulation would create, EPA in the ANPR discusses various alternatives under which, it 

suggests, it might be possible to mitigate the impact of PSD regulation on small sources: (1) 

reduce the number of sources subject to the program through “potential to emit” approaches; (2) 

increase the major source thresholds and PSD significance levels for GHGs “to permanently 

restrict the program to larger sources”; (3) phase in the applicability of PSD for GHGs; (4) 

develop streamlined approaches to implementing the BACT requirement; and/or (5) issue 

general permits for numerous similar sources. Id. at 44503/2. EPA notes that some legal 

barriers may exist for some of these options, and UARG agrees.

If EPA were to propose any regulation of GHGs that would trigger PSD, EPA would

need to address in detail the specific basis for any authority it believes it may have to mitigate the 

dramatic and disruptive effects on the nature and scope of the PSD program that would flow 

from any such regulation. This issue has generated substantial controversy because, for example, 

some environmental groups’ recent suggestions that EPA may have broad administrative or 

regulatory flexibility to mitigate or even avoid these effects are plainly contrary to their past 

statements. For example, in the past, environmental organizations and others have argued that 

EPA cannot issue general permits for PSD and that BACT determinations must be made on a 

case-by-case basis. See, e.g., Statement of David Hawkins, NRDC (stating that proposed utility 

BACT presumption for NOx emissions from modified electric utility steam generating units 

(proposed at 56 Fed. Reg. 27630, 27638 (June 14, 1991)) had “no legal basis” because “[t]he Act 

specifies that BACT control decisions must be made on a case-by-case basis”); Statement of 

Congressman Henry A. Waxman (stating with regard to the same proposed utility BACT 

presumption that “[i]t is highly unusual -- if not illegal -- for EPA to set a federal BACT 

presumption”). EPA would need to explain in any proposed rulemaking on GHG regulation 
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under the CAA why those prior arguments are incorrect and why contrary views now expressed 

by certain representatives of those groups can be relied on with assurance. See Bookbinder 

Testimony at 9 (noting that a “possibility” to avoid the PSD problem would be to “allow[] for 

coverage of all sources below an individual permitting level (again, possibly 5-10,000 [tons per 

year]) to be covered by a general permit”). In addition, UARG notes that the thresholds for PSD 

applicability are written directly into the statute itself. If EPA decides to increase these 

thresholds to ensure that PSD applies only to large sources, it will need to justify its legal 

authority to take that step without express congressional approval.

EPA also states its belief that PSD program requirements become applicable on the 

effective date of the first regulation requiring GHG control under the Act. 73 Fed. Reg. at 

44500/1. UARG notes that exactly when a regulation becomes “effective” can vary depending 

on the CAA provision at issue. For example, section 202(a)(2) of the Act specifies that any 

section 202(a)(1) emission standard for new motor vehicles “shall take effect after such period as 

the Administrator finds necessary to permit the development and application of the requisite 

technology, giving appropriate consideration to the cost of compliance within such period.”

UARG joins EPA in its “strong[] belie[f]” that any CAA regulation of a GHG for the first 

time would have to be coordinated carefully with a lawful and appropriate approach to PSD 

permitting, and EPA must consider the effects of regulation under the PSD program when it 

decides whether to propose to regulate GHGs under the Act. 73 Fed. Reg. at 44510/1. EPA 

states that this “is necessary to minimize confusion on the part of sources, permitting authorities, 

and the public, to provide for as effective a transition as possible, and to ensure that the strategies 

intended to avoid problems can be in place in time to prevent those problems.” Id. UARG 

agrees that, because of the overwhelming burden on administrative agencies and regulated 
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entities that would occur if GHGs become regulated pollutants for purposes of the PSD program, 

EPA would have to consider carefully not only the nature but also the timing of any regulation of 

GHGs under the CAA. Moreover, to the extent EPA believes it can propose alternatives to ease 

this regulatory burden, it would have to provide in any notice of proposed rulemaking a complete

and adequate explanation of the authority it believes it has to accomplish this and regarding how 

its action would not conflict with positions previously taken by the Agency or the courts in this 

matter.

F. Implications for the Title V Operating Permit Program Due to Possible 

Regulation of GHGs Under the CAA

Regulation of GHGs under any of the CAA provisions described above, including the 

PSD program, could give rise to applicable requirements that would need to be included in a 

Title V permit. In a GHG regulatory environment, if a source emits greater than 100 tons per 

year of a GHG, including CO2, it would need to apply for a Title V permit within one year of 

becoming subject to Title V requirements. The Title V permit for that source would include not 

only applicable requirements for the GHG but also general requirements that apply to other 

pollutants such as generally applicable opacity limitations that exist in several SIPs. 73 Fed. 

Reg. at 44510/2.

EPA notes that the Title V permit program would bring in even more sources than the 

PSD program because the 100-ton-per-year cutoff applies to all source categories, not only to 

categories listed in the CAA. Id. at 44511/1. EPA estimates that more than 550,000 sources 

would require Title V permits.32 Currently, there are approximately 15,000-16,000 Title V 

sources. Id. at 44511/1-2.

32 EPA states that if it decided to regulate GHGs as HAPs under section 112, Title V would 

apply at an even lower threshold (25 tons per year for any combination of HAPs and 10 tons per 

(continued...)
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EPA also expresses concern that Title V permits might have to be continually reopened 

as GHG regulation goes into effect under the Act. The hypothetical example EPA gives involves

mobile source requirements for GHGs taking effect, triggering Title V permitting requirements. 

Small GHG sources would need to obtain Title V permits even though these sources would, at 

that time, have no applicable requirements. If additional regulations are promulgated and take 

effect, permits with three or more years remaining would need to be reopened within 18 months 

to incorporate any applicable requirements from the new regulations. (Permits with less than 

three years remaining do not need to be reopened; applicable requirements are added to those 

permits at the time of renewal.) Id. at 44514/1-2. As EPA notes, “[t]his scenario would result in 

duplicative effort as permitting authorities issued hundreds of thousands of minimal Title V 

permits with no GHG requirements, followed by a period of numerous reopenings for some 

GHG source categories, while the requirements for other GHG source categories would remain 

off-permit until renewal, at which point they would need to be included in the renewal permit.” 

Id. at 44514/2.

UARG agrees with EPA that the burden of Title V permits and reopenings in a GHG 

regulatory context would be overwhelming. Id. at 44512/1. In addition, EPA expresses concern 

that there would be relatively little benefit from regulating these small sources because of the 

lack of anticipated add-on control devices at such sources and their relatively small emissions. 

Id. at 44512/2. Although UARG agrees that there likely would be little demonstrable benefit 

year for any single HAP). This is one of the many problems with potential regulation under 

section 112, according to the Agency. 73 Fed. Reg. at 44511/2. If EPA decided to use section 

112 to regulate GHGs, the number of sources needing a Title V permit “would easily number in 

the millions absent a means to limit [potential to emit].” Id. Moreover, section 112 does not 

exclude fugitive emissions, a fact that would capture even more sources under Title V, such as 

agriculture and mining sources. Id. at 44511/2-3.
130

from regulating these small sources, it notes that Congress enacted these requirements of the 

Title V operating permit in the Act, and EPA is bound to follow the directives of Congress.

EPA describes several alternatives that it suggests might address the burden of the Title V 

program in the GHG context. EPA attempts to justify these putative alternatives on two general 

grounds: (1) application of the literal language of the CAA results in absurd results contrary to 

congressional intent; and (2) a literal application of the Act results in administrative burden.33

Id. at 44512/3-44513/1. To deal with the problem of so many additional sources having to obtain 

Title V permits, EPA discusses the possibility of a phased-in approach to Title V permitting, 

which would defer Title V permitting for GHG sources until they become subject to applicable 

requirements for GHGs. Id. at 44513/1. EPA also discusses the possibility of phasing in Title V 

applicability by starting with the largest sources of GHGs first and phasing in the smaller 

sources. Id. Finally, EPA addresses the possibility of using general permits under Title V, 

although EPA expresses concern that, even with general permits for Title V, “the sheer volume 

of sources and number of different types of sources affected [would] present challenges.” Id. at

44513/2. UARG believes that legal barriers exist that might well prevent EPA from 

implementing these alternative approaches.

As with the PSD program, UARG believes that EPA would need, in any notice of 

proposed rulemaking for GHG regulation, to address the specific basis for any authority it

believes it may have to mitigate the dramatic and disruptive effects on the nature and scope of 

the Title V program that would flow from a decision to regulate GHGs under the Act. As with 

PSD, emission thresholds that give rise to Title V permit obligations are in the text of the CAA, 

33 EPA used these same two general grounds as a possible justification for measures to provide 

relief in the PSD context as well. See, e.g., 73 Fed. Reg. at 44503/2-3.
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as are the timetables by when Title V permits must be applied for or reopened. In proposing or 

adopting any measures intended to mitigate the impact of GHG regulation on the Title V 

program, EPA would have to justify its ability and authority to do so without express

congressional approval.

A problem also arises with the fees for Title V permitting in a potential GHG regulatory

environment. Title V requires permitting authorities to collect permit fees adequate to cover the 

costs of running the Title V program. Id. at 44512/1. In the case of GHGs, the cost may be 

extremely high, especially with respect to small sources. Yet EPA suggests that, because most 

states charge Title V fees on a dollar-per-ton basis, EPA “expect[s] that the fee revenues [for 

GHG sources] would be grossly excessive for what is needed to process permits for GHG 

sources. This is particularly true for the universe of small sources brought into Title V solely for 

their GHG emissions because those permits are expected to be relatively simple and may be 

addressed through general permits.” Id. at 44513/3. Thus, EPA asserts that permitting 

authorities would need to consider other options for fees, such as a lower per-ton fee amount for 

GHGs, fixed fees for applicants below a certain size, and/or no fees for smaller GHG sources. 

Id.

Should EPA propose regulation of GHGs under Title V, UARG believes that Title V 

permitting fees should apply consistently to all sources regardless of source size. As EPA notes, 

Title V requires that the permitting programs be self-funding. Rather than set fixed fees for 

applicants below a certain size or provide an exemption from fees for smaller GHG sources, in 

the event of any GHG regulation, permitting authorities should institute a lower dollar-per-ton 

fee amount for GHGs to account for the large volume of GHGs, particularly CO2, that sources 
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emit. This approach, or any other fee relief, should apply to all Title V sources regardless of 

size. Large sources should not have to bear the permitting cost for smaller sources.

As with PSD, EPA needs to consider carefully the effects on the Title V permitting 

program when it makes any decision whether to propose regulation of GHGs under the CAA. Id. 

at 44514/1. UARG agrees that, because of the overwhelming burden on administrative agencies 

and regulated entities that would occur if GHGs become regulated pollutants for purposes of the 

Title V program, EPA would have to consider carefully the nature and timing of any regulation. 

Moreover, to the extent EPA believes it can propose alternatives to ease this regulatory burden, it 

would have to provide in any notice of proposed rulemaking a complete and adequate 

explanation of the authority it believes it has to accomplish this and regarding how its action 

would not conflict with positions previously taken by the Agency or the courts in this matter.

G. Title VI of the CAA, Which Addresses Stratospheric Ozone Protection, Does 

Not Provide EPA with Authority To Regulate GHGs.

As EPA notes, section 615 of the CAA provides specific regulatory authority to address 

effects on the stratosphere. That section, like the other provisions of Title VI, does not authorize 

regulatory action to control emissions of GHGs or to address global climate change. 

Section 615 and the other provisions of Title VI must be construed in light of the specific 

stratospheric-ozone-protection purpose of that title and Congress’s direction -- in the one 

provision of Title VI that expressly refers to “global warming” (section 602(e)) -- that the 

Administrator’s obligation to publish the global warming potential of listed Title VI substances 

“shall not be construed to be the basis of any additional regulation under this [Act].” See 73 Fed. 

Reg. at 44518/3-44519/1 (quoting CAA § 602(e)). Moreover, in enacting Title VI in 1990, 

Congress rejected the Senate Environment and Public Works Committee’s proposed approach to 

the issue, which was to combine regulatory authority to limit emissions of stratospheric-ozone-
133

depleting substances with regulatory authority to control emissions of GHGs. See S. REP. NO. 

101-228, at 377-402, 682-701 (1989), reprinted in A Legislative History of the Clean Air Act 

Amendments of 1990, Vol. 5 at 8338, 8717-42, 9022-41 (Nov. 1993) (describing and setting out 

the provisions of the proposed but never-enacted “Stratospheric Ozone and Climate Protection 

Act”). Thus, the Senate committee proposed to provide, in its version of what became Title VI, 

authority “to reduce the generation of greenhouse gases in order ... to limit anthropogenically 

induced global climate changes” and “to reduce to the maximum extent possible emissions of ... 

gases caused by human activities that are likely to affect adversely the global climate.” See id. at 

683, 684 (setting out text of proposed CAA § 502(a), (b)). The committee’s description of these 

proposed provisions emphasized that “global climate change resulting from an intensified 

greenhouse effect” was a “distinct” problem from “destruction of the stratospheric ozone layer.” 

Id. at 387. Yet Congress, in enacting Title VI, tellingly refused to enact the GHG regulatory

authority proposed by the committee.

As EPA observes, section 615 “was intended to augment other authorities and 

responsibilities established by Title VI.” 73 Fed. Reg. at 44519/2. As discussed above, those 

other authorities and responsibilities address protection of the stratosphere from depletion of 

ozone, not broader concerns about global climate changes and the role of GHG emissions with

respect to such changes. 

Moreover, even if section 615 could be construed to grant regulatory authority to control 

GHG emissions to address global climate change, EPA, to invoke any such authority, plainly

“would have to consider whether available scientific information supports making the requisite 

findings.” Id. Indeed, EPA at a minimum would have to have scientific information sufficient to 

demonstrate that (1) particular emissions of GHGs “may reasonably be anticipated to affect the 
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stratosphere” and (2) the effect on the stratosphere “may reasonably be anticipated to endanger 

public health or welfare.” Id. at 44519/1 (quoting CAA § 615). EPA’s discussion of this issue in 

the ANPR indicates that, in the Agency’s own view, available scientific information is, at least at 

this time, not sufficient to establish the basis for any such findings under section 615. See id. at 

44519/2-3.

VII. Conclusion

UARG appreciates the opportunity to comment on the ANPR. UARG agrees with EPA’s 

decision to examine the possibility of GHG regulation under the current CAA in the broadest 

context, especially because the scope of such regulation would be greater than that of any 

previous CAA program. As these comments demonstrate, the basis for any proposed regulation 

of GHG emissions under the existing provisions of the CAA has not been established. In any 

event, in determining whether to propose regulation of GHG emissions under the CAA, EPA 

must examine carefully the effects that any such regulation would have within the United States, 

including effects on the economy, and should consider and engage the issues addressed in the 

comments on this ANPR.