Endangerment and Cause or 

Contribute Findings for 

Greenhouse Gases Under 

Section 202(a) of the Clean Air 

Act: 

EPA’s Response to Public 

Comments 

Volume 8: Impacts and Risks to 

Public Health and Welfare: 

Other Sectors
Impacts and Risks to Public Health 

and Welfare: Other Sectors 

U. S. Environmental Protection Agency 

Office of Atmospheric Programs 

Climate Change Division 

Washington, D.C. 
FOREWORD 

This document provides responses to public comments on the U.S. Environmental Protection Agency’s 

(EPA’s) Proposed Endangerment and Cause or Contribute Findings for Greenhouse Gases Under Section 

202(a) of the Clean Air Act, published at 74 FR 18886 (April 24, 2009). EPA received comments on 

these Proposed Findings via mail, e-mail, and facsimile, and at two public hearings held in Arlington, 

Virginia, and Seattle, Washington, in May 2009. Copies of all comment letters submitted and transcripts 

of the public hearings are available at the EPA Docket Center Public Reading Room, or electronically 

through http://www.regulations.gov by searching Docket ID EPA-HQ-OAR-2009-0171. 

This document accompanies the Administrator’s final Endangerment and Cause or Contribute Findings 

for Greenhouse Gases Under Section 202(a) of the Clean Air Act (Findings) and the Technical Support 

Document (TSD), which contains the underlying science and greenhouse gas emissions data. 

EPA prepared this document in multiple volumes, with each volume focusing on a different broad 

category of comments on the Proposed Findings. This volume of the document provides responses to 

public comments regarding impacts and risks to public health and welfare in other sectors. 

In light of the very large number of comments received and the significant overlap between many 

comments, this document does not respond to each comment individually. Rather, EPA summarized and 

provided a single response to each significant argument, assertion, and question contained within the 

totality of comments. Within each comment summary, EPA provides in parentheses one or more lists of 

Docket ID numbers for commenters who raised particular issues; however, these lists are not meant to be 

exhaustive and EPA does not individually identify each and every commenter who made a certain point in 

all instances, particularly in cases where multiple commenters expressed essentially identical arguments. 

Several commenters provided additional scientific literature to support their arguments. EPA’s general 

approach for taking such literature into consideration is described in Volume 1, Section 1.1, of this 

Response to Comments document. As with the comments, there was overlap in the literature received. 

EPA identified the relevant literature related to the significant comments, and responded to the significant 

issues raised in the literature. EPA does not individually identify each and every piece of literature 

(submitted or incorporated by reference) that made a certain point in all instances. 

Throughout this document, we provide a list of references at the end of each volume for additional 

literature cited by EPA in our responses; however, we do not repeat the full citations of literature cited in 

the TSD. 

EPA’s responses to comments are generally provided immediately following each comment summary. In 

some cases, EPA has discussed responses to specific comments or groups of similar comments in the 

Findings. In such cases, EPA references the Findings rather than repeating those responses in this 

document. 

Comments were assigned to specific volumes of this Response to Comments document based on an 

assessment of the principal subject of the comment; however, some comments inevitably overlap multiple 

subject areas. For this reason, EPA encourages the public to read the other volumes of this document 

relevant to their interests. 

iii 
TABLE OF CONTENTS 

8.0 Impacts and Risks to Public Health and Welfare: Other Sectors 

8.1 Energy, Infrastructure, and Settlements ........................................................ 1 

8.2 National Security .............................................................................................. 9 

8.3 Impacts in Other World Regions................................................................... 13 

8.4 Vulnerable Populations ................................................................................. 17 

Acronyms and Abbreviations 

CCSP U.S. Climate Change Science Program 

cm centimeter 

CNA Center for Naval Analyses 

ECWS East Coast winter storms 

EPA U.S. Environmental Protection Agency 

F degrees Fahrenheit

GHG greenhouse gases 

IPCC Intergovernmental Panel on Climate Change 

mm/yr millimeters per year 

NRC National Research Council 

sq. km square kilometer 

TSD Technical Support Document 

USGCRP U.S. Global Change Research Program 

iv 
8.0 Impacts and Risks to Public Health and Welfare: Other Sectors 

8.1 Energy, Infrastructure, and Settlements 

Comment (8-1):

Several commenters (3347.1, 3394.1, 3449.1, 3747.1, 7020) state that EPA should include in the 

Technical Support Document (TSD) an accounting of what the net effect of climate change will be on 

sectors such as energy consumption, energy production, and transportation. Assertions by the commenters 

include: that the paragraph in the Proposed Findings on energy, infrastructure, and settlements is 

“exceptionally vague”; that the TSD statement that “significant uncertainty exists about the potential 

impacts of climate change on energy production and distribution, in part because the magnitude and 

timing of climate impacts are uncertain” is insufficient; that the TSD fails to note whether impacts in this 

section are positive or negative; and that the EPA engages in “speculation” by making a finding of 

“reasonably anticipated” endangerment while stating that U.S. energy use will be “affected” by climate 

change and admitting that the net effect on domestic energy consumption is unknown. Overall, the 

commenters assert that the level of uncertainty that is expressed in the current Energy, Infrastructure, and 

Settlements section does not justify a finding of “reasonably anticipated” endangerment. 

Response (8-1):

With regard to the comment that the language in the Proposed Findings was vague, we carefully reviewed 

the relevant section in the Proposal and in the assessment literature. We have revised this section in the 

Final Findings accordingly; see the Findings, IV.B.2.e, “Energy, Infrastructure and Settlements.” 

With regard to net effects, see the Findings, Section IV.B, “The Air Pollution Is Reasonably Anticipated 

to Endanger Both Public Health and Welfare,” for our response to comments on how the Administrator 

weighed the scientific evidence underlying her endangerment determination. 

Commenters do not explain how our statement regarding uncertainties of the potential impacts of climate 

change on energy production and distribution is “insufficient.” The referenced statement in the TSD cites 

CCSP (2007a), and the statement is located on page 48 of that report. CCSP (2007a), as part of the body 

of peer-reviewed assessment literature summarized in the TSD, expresses the uncertainty associated with 

projected impacts of climate change and those uncertainties have subsequently been carried over into 

TSD as well. For example, the TSD cites CCSP (2007a) in stating that “Climate change impacts on U.S. 

electricity generation at fossil and nuclear power plants are likely to be similar.” In addition, please see 

Volume 1: General Approach of the Technical Support Document, for EPA’s response to comments on 

the approach taken in developing the TSD, and the communication of uncertainty as expressed in the 

underlying scientific literature. 

We disagree with the commenters that the TSD should have further characterized in this section whether 

the impacts were positive or negative. The TSD, including Section 13, reflects the findings of the peerreviewed assessment literature and reflects, to the extent that this literature does, the “positive” or 

“negative” nature of an impact. For example, the TSD states that “[w]here extreme weather events 

become more intense and/or more frequent with climate change, the economic and social costs of these 

events will increase (high confidence) (Wilbanks et al., 2007).” See the Findings, Section IV.B, “The Air 

Pollution is Reasonably Anticipated to Endanger Both Public Health and Welfare,” for a discussion of 

EPA’s approach to positive and negative impacts. 

With regard to the comment that a finding of “reasonably anticipated” endangerment is not justified based 

upon this section, see the Findings, Section IV.B, “The Air Pollution is Reasonably Anticipated to 

Endanger Both Public Health and Welfare,” for a discussion of the Administrator’s determination. 

1 
Comment (8-2):

One commenter (3394.1) states that Section 13 of the TSD on Energy, Infrastructure, and Settlements 

unjustifiably favors those studies that suggest impacts will be significant over those that predict the 

opposite, particularly in the area of energy use for heating and cooling. The commenter states that the 

TSD acknowledges that the net effect on energy consumption is unclear but singles out one “study that 

predicts a significant increase in electricity demand requiring substantial investment in new generation.” 

The commenter additionally states that “EPA apparently has not evaluated this study itself and only refers 

to a CCSP synthesis report that apparently cites it. Id. at 106.” Finally, the commenter states that EPA has 

“deemphasize[d] the greater body of science on this issue.” 

Response (8-2):

The TSD provides a balanced summary of key synthesis reports. First, we note that the “study” the 

commenter singles out is CCSP (2007a), which is an assessment report that assesses the literature on 

Effects of Climate Change on Energy Production and Use in the United States and synthesizes the results 

of multiple studies. The “greater body of science on this issue” is precisely what the CCSP report covers. 

It states: “The process for producing the report was focused on a survey and assessment of the available 

literature.” See the Findings, Section III.A., “The Science on Which the Decisions Are Based,” for our 

response to comments on the use of the assessment literature and our treatment of new and additional 

scientific literature provided through the public comment process. 

In addition, since release of CCSP (2007a), the U.S. Global Change Research Program (USGCRP) has 

released a new assessment report (Karl et al, 2009), which reinforces the key conclusions of CCSP 

(2007a). We have revised the TSD to reflect the key conclusion on this issue in Karl et al. (2009): 

“Warming will be accompanied by decreases in demand for heating energy and increases in demand for 

cooling energy. The latter will result in significant increases in electricity use and higher peak demand in 

most regions.” Finally, we note that the commenter did not provide references to any studies that would 

represent “the greater body of science” on this issue to support the commenter’s assertions. For these 

reasons, the discussion of this issue in the TSD accurately and clearly reflects the consensus findings 

represented in the peer-reviewed assessment literature. 

Comment (8-3):

Several commenters state that specific aspects of the climate impacts evidence summarized in the TSD 

with respect to energy, infrastructure, and settlements do not support the Administrator’s endangerment 

finding. 

Response (8-3):

The specific issues that underlie these comments are addressed in the responses throughout this volume, 

and other volumes of the Response to Comments document. With regard to the commenters' conclusion 

that the current science does not support an endangerment finding with respect to energy, infrastructure, 

and settlements, we disagree based on the scientific evidence before the Administrator. See the Findings, 

Section IV.B, “The Air Pollution is Reasonably Anticipated to Endanger Both Public Health and 

Welfare,” for details on how the Administrator weighed the scientific evidence underlying her 

endangerment determination in general, and with regard to the energy, infrastructure, and settlements 

sector in particular. 

Comment (8-4):

2 
One commenter (3136.1) states that the TSD devotes significant space to the impacts of climate change 

on native settlements in Alaska. The commenter states that the native population of Alaska has been 

dealing with coastal erosion and periods of warming for many thousands of years. The commenter argues 

that the problems facing these groups are due not to climate change itself but to transitioning from their 

old nomadic way of life to permanent settlements, which has restricted their ability to respond to 

variations in the climate. 

Response (8-4):

Whether or not native Alaskan communities have been experiencing warming or coastal erosion in the 

past is not dispositive of the question of whether present and projected climate change impacts pose a 

danger to these settlements. The TSD summarizes the risks to Native Alaskans posed by climate change, 

including access to food sources and increased risk of flooding and erosion. 

With regard to the commenter’s statement that a transition from a nomadic lifestyle is responsible for a 

restricted ability to respond to variations in climate, we note that climate change impacts are not 

necessarily dependent on a group being nomadic or living in fixed structures. Additionally, in the context 

of determining whether greenhouse gases (GHGs) endanger public health and welfare, it is not 

appropriate for EPA to engage in hypotheticals regarding how if certain cultures or settlements were 

different today, their circumstances might alter their vulnerability to climate change. Rather, regardless of 

whether the alleged change to permanent settlements exacerbates the impacts, the evidence of climate 

impacts to native settlements in Alaska is relevant to determining endangerment. 

Finally, see the Finding, Section III.C, “Adaptation and Mitigation,” for our response to comments and 

approach on the treatment of adaptation and mitigation in the Findings. 

Comment (8-5):

One commenter (3136.1) criticizes the TSD for using the word “will” in describing the impacts of 

extreme events on transportation. The commenter states that the word “may” should be used instead 

because there is a lack of a signal of increasing extremes related to climate change in the observed record. 

Several commenters, including 3136.1 and 3596.2, cite Roger Pielke, Jr.’s assessment of the U.S. Climate 

Change Science Program (CCSP) conclusions on extreme events and climate change—specifically, that 

there is a lack of evidence of trends toward increasing extreme events in the United States. They present 

six points that are mentioned: 

1. Over the long-term U.S. hurricane landfalls have been declining. 2. Nationwide there 

have been no long-term increases in drought. 3. Despite increases in some measures of 

precipitation, there have not been corresponding increases in peak streamflows (high 

flows above 90th percentile). 4. There have been no observed changes in the occurrence 

of tornadoes or thunderstorms. 5. There have been no long-term increases in strong East 

Coast winter storms (ECWS), called Nor’easters. 6. There are no long-term trends in 

either heat waves or cold spells, though there are trends within shorter time periods in the 

overall record. 

One commenter (3596.2) goes on to state that there is no strong support for increased hurricane intensity 

or frequency in the future. The commenter argues that the lack of correlation between global temperature 

and U.S. extreme events undermines support for a positive endangerment finding. 

Response (8-5):

The comment that EPA should have used the word “may” instead of “will” refers to wording in a twosentence quote taken directly from the summary of a peer-reviewed assessment report produced by the 

3 
National Research Council (NRC, 2008). We note that the Intergovernmental Panel on Climate Change 

(IPCC) and other assessment reports assign probabilities to the projected effects of climate change; these 

probabilities have been characterized in the Introduction to the TSD. The NRC (2008) report assigned 

probabilities to projected effects, such as those in the sentence referred to by the commenter. For 

example, Box S-1 on pages 3 and 4 of NRC (2008) describes the probabilities that the report assigns to 

those climate change impacts deemed to be of greatest relevance for U.S. transportation. Thus, because 

the NRC has assigned probabilities and taken these into account when using the word “will” in the 

sentence in question, and given that our summary in the TSD attributes the statement to the NRC, the 

language in the TSD is accurate. 

For EPA’s response to comments received on the six issues raised by commenters (with the exception of 

streamflow) regarding the evidence toward increasing extreme events in the United States, see Volume 2 

of the Response to Comments document. 

For response to comments received on streamflow, future hurricane intensity and frequency, and the 

correlation between global temperature and U.S. extreme events, see Volume 4 of the Response to 

Comments document. 

Comment (8-6):

One commenter (3283.1) notes that energy efficiency continues to increase without greenhouse gas 

regulations, through such efforts as ENERGY STAR, renewable energy programs, and tax credits, and 

that “efficiency gains continue to dominate the energy sector.” The commenter states that “EPA points 

out that climate change will have a limited impact on heating and cooling demand (+/- 5%). In California, 

they cite a 20% per capita increase in electricity for cooling under a worst-case scenario of about 10° 

Fahrenheit (F) heating if there is limited implementation of efficiency measures.” The commenter goes on 

to note that “Energy Star programs are rapidly causing large efficiency improvements in replacement 

cooling systems” and that new construction can greatly reduce cooling loads. 

Response (8-6):

It is not clear how the commenter believes these statements are relevant to the endangerment or cause or 

contribute findings. To the extent that the commenter is arguing that “efficiency gains” will somehow 

enable the energy sector to reduce or avoid climate impacts, the commenter does not provide evidence to 

support the argument. See the Findings, Section III.C, “Adaptation and Mitigation,” for our response to 

comments on the treatment of adaptation and mitigation in the Findings. 

We also note that the TSD does not state that climate change will have a limited impact on heating and 

cooling demand. Rather, the TSD states that “Generally speaking, the net effects of climate change in the 

United States on total energy demand are projected to amount to between perhaps a 5% increase and 

decrease in demand per 1oC in warming in buildings.” Additionally, we have updated the TSD to include 

the following statement: 

Climate warming will be accompanied by decreases in demand for heating energy and 

increases in demand for cooling energy. The latter will result in significant increases in 

electricity use and higher peak demand in most regions (Karl et al., 2009). 

Comment (8-7):

One commenter (3394.1) criticizes the TSD for engaging in speculation by noting that industries and 

settlements have become resilient to climate variability but then suggesting that impacts will be greater 

4 
than the capacity to adapt. The commenter states that without evidence, this assertion is unwarranted. 

Additionally, the commenter claims that “[t]his section of the TSD acknowledges that adaptive capacity is 

a significant factor in determining the severity of impacts to human settlements. Id. at 111” and criticizes 

the TSD for omitting an analysis of adaptation from its assessment. 

Response (8-7):

After review of the section in question, EPA disagrees with the assertion that we engaged “in speculation” 

and notes that the commenter did not provide any specific examples, suggested revisions, or new data for 

our consideration. Also, the commenter mischaracterizes EPA’s statements about adaptive capacity in the 

TSD. The commenter refers to page 111 for the claim above, and we note that the relevant text on that 

page of the April 2009 version of the TSD is a quote from an assessment report (IPCC 2007b) that reads 

as follows: 

Poor communities can be especially vulnerable, in particular those concentrated in highrisk areas. They tend to have more limited adaptive capacities, and are more dependent 

on climate-sensitive resources such as local water and food supplies (high confidence). 

This passage clearly states that poor communities can be especially vulnerable to climate change impacts 

because of more limited adaptive capacities, and clearly does not state or imply—as the commenter 

asserts—that adaptive capacity is a determining factor in the severity of the climate change impacts 

themselves. See the Findings, Section III.C, “Adaptation and Mitigation,” for our response to comments 

on and treatment of adaptation and mitigation in the Findings. 

Comment (8-8):

One commenter (3394.1) criticizes the TSD for stating that no single hurricane can be attributed to 

climate change yet then “engag[ing] in an indirect but speculative attempt to make such an attribution” in 

stating that the damages from Hurricanes Ivan, Katrina, and Rita are indicators of future climate change 

impacts. 

Response (8-8):

EPA is clear in the TSD that no single hurricane can be attributed to climate change, but it does not 

follow that the impacts associated with a particular past hurricane are not illustrative of the potential 

damages that could be associated with future hurricanes of similar intensity. The TSD first refers to the 

scientific literature regarding projections that suggest that extreme weather events are likely to become 

more intense, and then notes that the impacts of Katrina may be a possible indicator of the kinds of 

impacts that could occur from more intense extreme weather events. This point is confirmed in CCSP 

(2007a), which states that “[i]ncreases in storm intensity could threaten further disruptions of the sorts 

experienced in 2005 with Hurricanes Katrina and Rita.” Thus, EPA approach in the TSD is reasonable. 

Comment (8-9):

One commenter (3394.1) argues that the TSD claims incorrectly that land subsidence is a climate changerelated occurrence. 

5 
Response (8-9):

We have reviewed the TSD in light of this comment and have concluded that it neither claims nor gives 

the impression that land subsidence is a climate change-related occurrence. The comment refers to a quote 

from NRC (2008): “Climate change will affect transportation primarily through increases in several types 

of 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.” We find the existing 

sentence to be clear: storm surges and land subsidence are factors which can exacerbate the impacts of sea 

level rise. 

Comment (8-10):

One commenter (3561.1) argues that EPA should evaluate the impact of climate change on population 

migration patterns in the United States. 

Response (8-10):

In response to this comment, we have added additional information on urban vulnerabilities in Section 13, 

as well as a discussion of U.S. regional climate impacts in Section 15 of the TSD. We note that the peerreviewed assessment literature, on which we rely for the TSD, is limited with regard to projections of 

U.S. population migration impacts, and thus we provide a qualitative, not quantitative, evaluation of this 

issue. 

Comment (8-11):

One commenter (7020) states that the TSD “fails to note a potential beneficial effect, in that a migration 

toward electricity (in place of primary fuels) will inherently tend to reduce greenhouse gas emissions as 

an appreciable fraction of electricity in the US that is generated from sources that do not emit greenhouse 

gases in operation.” 

Response (8-11):

See the Findings, Section III.C, “Adaptation and Mitigation,” for our response to comments on the 

treatment of adaptation and mitigation in the Findings. We further note that the commenter’s claim 

regarding an inherent reduction in greenhouse gas emissions associated with a shift toward electricity 

generation is by no means assured. Such an outcome would depend on fuel used, as well as the efficiency 

of the conversion of fuel to energy, in direct use and electric generation. 

Comment (8-12):

One commenter (7020) states that Section 13(c), “Infrastructure and Settlements,” overlaps with Section 

12(a), “Vulnerable Areas” in the TSD, and that this should be covered in one section for clarity. 

Response (8-12):

Upon review, we have decided not to integrate these two sections because they address different and 

important issues. The discussion in the Section 13 on energy, infrastructure, and settlements focuses on 

the range of potential climate impacts across this sector broadly, while the discussion of vulnerable areas 

in Section 12 is focused only on sea level rise and coastal areas. 

6 
Comment (8-13):

One commenter (7020) states, with regard to buildings, that the majority of the material relates to Russia 

and applicability to the United States is unclear. Additionally, the commenter states that the impacts to 

Alaskan buildings are not quantified. 

Response (8-13):

The discussion of thawing permafrost on Russian buildings is illustrative of the kinds of similar impacts 

that could manifest in certain regions of the United States as a result of climate change. As noted in 

Section 13 of the TSD, “The problems now being experienced in Russia may be expected to occur 

elsewhere in the Arctic if buildings are not designed and maintained to accommodate future warming 

(ACIA, 2004).” With regard to quantifying the impacts to Alaskan buildings, we have added the 

following sentence to the TSD: “Overall, the cost of maintaining Alaska’s public infrastructure is 

projected to increase 10 to 20 percent by 2030 due to warming, costing the state an additional $4 billion to 

$6 billion, with roads and airports accounting for about half of this cost (Karl et al., 2009).” As noted in 

Karl et al. (2009), private infrastructure impacts in Alaska have not been evaluated. We note that 

quantification of an impact is not required before the Administrator may consider information in an 

endangerment analysis. See the Findings, Section IV.B, “The Air Pollution is Reasonably Anticipated to 

Endanger Both Public Health and Welfare,” for a discussion of how the Administrator approaches the 

evidence regarding endangerment. 

Comment (8-14):

One commenter (7020) criticizes the TSD for failing to quantify the effects on indigenous populations in 

Alaska. The commenter argues that the TSD would better support an endangerment finding if it included 

such a quantification. 

Response (8-14):

Quantitative information about risks to indigenous Alaskan settlements due to climate change is relevant 

to and provides support for an endangerment analysis, and such information is included in the most recent 

USGCRP assessment report. Therefore, we have added the following statement to Section 15 of the TSD 

from Karl et al. (2009): “Over 100 Native Alaskan villages on the coast and in low-lying areas along 

rivers are at risk of increased flooding and erosion due to warming.” We note that quantification of an 

impact is not required before the Administrator may consider information in an endangerment analysis. 

See the Findings, Section IV.B, “The Air Pollution is Reasonably Anticipated to Endanger Both Public 

Health and Welfare,” for a discussion of how the Administrator approaches the evidence regarding 

endangerment. 

Comment (8-15):

One commenter (3136.1) criticizes the report by the California Energy Commission cited in the TSD that 

stated that annual electricity demand for air conditioning in the state may increase as much as 20% by 

2100. Specifically, the commenter states that three underlying assumptions of the report are that the 

population will be unchanged in 2100, that energy efficiency measures will not be implemented, and that 

the “high range temperature scenario” will come to pass. The commenter concludes that these 

assumptions are unrealistic, thereby rendering the 20% figure meaningless. The commenter also states 

that this figure must be compared against the figure from a non-climate-change scenario to have any 

meaning. 

Response (8-15):

7 
We disagree with the commenter that the conclusion of the California Energy Commission (2006) report 

with regard to electricity consumption cited in the TSD is “meaningless.” On the contrary, we find that it 

provides an important quantified example of the potential impacts of climate change on electricity use 

under a high-temperature-rise scenario. In the TSD, we clearly state the three underlying assumptions that 

the commenter pointed out. The commenter argues that these assumptions are unrealistic; however, the 

report’s methodology was judged to be sufficient by the peer-reviewed assessment report CCSP (2007a), 

which cited the report. Because of this, we conclude that the assumptions are entirely valid for purposes 

of examining the possible effects of climate change under certain stated conditions. Finally, with regard to 

the commenter’s criticism that the figure must be compared against a non-climate-change scenario to be 

meaningful, we note that the estimated increase in annual electricity use figure quoted in the report is 

relative to the 1961–1990 base period. To give better meaning to the discussion of this report’s findings in 

the TSD, we have clarified the TSD to note this base period used for comparison. 

Comment (8-16): 

A commenter (2818) states the importance of infrastructure—including water and sewage treatment 

plants, roads and transportation systems, hospitals, and disaster response systems—and asserts that there 

is a strong link between this infrastructure, which is threatened by climate change impacts such as sea 

level rise and health. 

Response (8-16): 

We agree with the commenter that climate change poses a threat to infrastructure and that if infrastructure 

were disabled that there could be public health and welfare impacts. The assessment literature finds that 

there are a number of high-likelihood impacts on infrastructure as summarized in Section 13 of the TSD. 

Comment (8-17): 

A commenter (3686.1) contends that the TSD fails to mention the severe consequences of increased 

hurricane intensity on the electricity infrastructure of Louisiana and the Gulf Coast. 

Response (8-17): 

EPA recognizes that hurricane intensity has significant implications for the infrastructure of Louisiana 

and the Gulf Coast, including electricity infrastructure, and this is mentioned in Section 13 of the TSD. 

We have also revised the TSD to include new information from Karl et al (2009): “It is not yet possible to 

project effects of climate change on the grid, because so many of the effects would be more localized than 

current climate change models can depict; but, weather-related grid disturbances are recognized as a 

challenge for strategic planning and risk management.” 

Comment (8-18): 

One commenter (3216.1) notes that communities can be displaced as a result of “increased natural 

disasters,” and states that “The aftermath of Hurricane Katrina demonstrated that communities affected by 

a natural disaster can take years to rebuild after their fragile infrastructure is destroyed.” 

Response (8-18):

We agree with the commenter’s point that natural disasters caused by extreme weather events can have 

lasting consequences, including displacement of communities. See Volume 4 of the Response to 

Comments document for our response to comments on projected climate change impacts on extreme 

weather events. 

8 
8.2 National Security 

Comment (8-19):

A commenter (3702.1) states that the national security impacts identified in the TSD are too “speculative 

and attenuated” to be used for an endangerment finding. In particular, the commenter argues that indirect 

impacts are inadequate to support a finding that climate change endangers U.S. national security since 

they “involve multiple, complex causal factors involving undefined social, political, and economic events 

that may or may not occur.” 

Response (8-19):

EPA has reviewed Section 16 of the TSD in light of the comments and disagrees that the potential 

national security impacts of climate change that we identify in the TSD are “speculative and attenuated.” 

Examination of the literature that EPA cites in the TSD confirms that this discussion is based upon bestavailable projections of future climate change impacts and expert assessment of the sociopolitical 

outcomes that could potentially result. In fact, the most recent assessment report of the USGCRP (Karl et 

al., 2009) provides additional discussion of this issue, and we have revised the TSD to include the 

following statement in Karl et al. (2009): 

In an increasingly interdependent world, U.S. vulnerability to climate change is linked to 

the fates of other nations. For example, conflicts or mass migrations of people resulting 

from food scarcity and other resource limits, health impacts, or environmental stresses in 

other parts of the world could threaten U.S. national security...Meeting the challenge of 

improving conditions for the world’s poor has economic implications for the United 

States, as does intervention and resolution of intra- and intergroup conflicts. Where 

climate change exacerbates such challenges, for example by limiting access to scarce 

resources or increasing incidence of damaging weather events, consequences are likely 

for the U.S. economy and security. 

The position taken in these comments—that the findings of assessments on national security impacts are 

inadequate because such impacts involve “multiple, complex causal factors” and rely on projections—is 

neither reasonable nor sound with respect to an assessment of the national security threats associated with 

climate change or other factors. There are few, if any, issues of this importance that are not affected by 

“multiple, complex causal factors.” We have determined that the discussion in the TSD clearly 

acknowledges the issues of concern to the commenters and provides an objective and thorough 

assessment of current understanding. Additionally, the literature relied upon in the TSD’s discussion of 

national security impacts has considered the “multiple, complex causal factors” that may be involved in 

such impacts and has determined that a significant likelihood exists of these impacts occurring. A 

summary of these determinations is provided in the TSD. See the Findings, Section III.A., “The Science 

on Which the Decisions Are Based,” for a discussion of our use of assessment literature. 

Comment (8-20):

A commenter (3702.1) criticizes EPA for apparently not consulting directly with any U.S. national 

security agencies to inform its proposal, as well as for only providing one relevant document from such an 

agency, the testimony of Dr. Fingar (Fingar, 2008). Similarly, another commenter (3394.1) maintains that 

EPA’s support for its national security section is “derived from non-scientific sources that are inherently 

speculative.” A commenter (3394.1) adds to this by calling EPA’s sources for its national security section 

a “speculative grab bag,” noting that the TSD itself notes that neither the Intergovernmental Panel on 

Climate Change (IPCC) nor the U.S. Climate Change Science Program (CCSP) has “explicitly addressed 

9 
these issues.” One commenter (3372.1) specifically criticizes the Center for Naval Analyses (CNA) 

Corporation report (CNA 2007), stating that the panel of advisors for the report was given science 

briefings based upon the IPCC, which the commenter asserts is a “flawed resource” and “vintage 

science.” The commenter also specifically criticizes two individuals who it states briefed the advisory 

board on the science: “Anthony Melillo (WRI, Heinz Foundation), co-chair of the discredited 2000 US 

National Assessment” and James Hansen. 

Response (8-20):

The sources for the national security section are not “speculative.” The latest U.S. government assessment 

report, Karl et al. (2009), discusses potential climate change impacts on national security, and we have 

updated the TSD to summarize the findings of this report. However, because this is an evolving topic area 

with limited information available in assessment reports, we also supplemented the discussion of national 

security impacts in the TSD with additional information. 

The sources that EPA relied on for characterizing the national security risks of climate change are U.S. 

government-published or government-funded analyses, as well as a CNA report. We consider these 

sources legitimate as they typically rely on the assessment literature for their underlying science. With 

regard to one commenter’s point, EPA did not directly consult with agencies responsible for U.S. national 

security on their assessment of impacts but rather examined published reports of the U.S. government. 

Additionally, we note that while the commenters criticized the sources used, they did not provide other 

literature for our review that discusses the risks to national security from climate change impacts. 

The CNA (2007) report, which a commenter specifically criticized, is a widely cited study that was 

compiled under the direction and review of an advisory board consisting of 11 retired three- and four-star 

admirals and generals from the U.S. military. The report states that information on the observed effects 

and projections of climate change impacts was drawn from the IPCC and “peer-reviewed scientific 

literature, and data, reports, and briefings from various respected sources, including the National 

Academy of Sciences, the National Oceanic and Atmospheric Administration, the National Aeronautic 

and Space Administration, and the United Kingdom’s Hadley Centre for Climate Change.” Six 

individuals of varying backgrounds and expertise are listed in the acknowledgments of the report as 

having supported the effort and eight other individuals are listed as having briefed the Military Advisory 

Board. Those individual briefers are: Dr. James Hansen, Dr. Anthony Janetos, Dr. Richard Moss, Mr. 

Justin Mundy, Maj. Gen. (Ret.) Richard Engel, Mr. Randy Overbey, Mr. Kenneth Colburn, and Dr. 

Robert Socolow. The combination of these individuals clearly represents a high level of knowledge with 

regard to the issues being discussed. Specifically, at the time of writing: Dr. James Hansen was the lead 

climate scientist and director of the NASA Goddard Institute for Space Studies; Dr. Anthony Janetos was 

the vice president of the H. John Heinz III Center for Science, Economics, and the Environment; Dr. 

Richard Moss was the senior director for Climate and Energy at the United Nations Foundation; Mr. 

Justin Mundy was the senior adviser to the Special Representative on Climate Change for the UK Foreign 

and Commonwealth Office; Maj. Gen. Richard Engel, USAF (Ret.), was the deputy national intelligence 

officer for science and technology at the National Intelligence Council; Mr. Randy Overbey was the 

former president of Alcoa Primary Metals Development; Mr. Kenneth Colburn worked for the Center for 

Climate Strategies; and Dr. Robert Socolow was a professor at Princeton University. 

The commenter specifically criticized two of those aforementioned individuals who briefed the report’s 

advisory board: Dr. Anthony Janetos and Dr. James Hansen. The commenter did not assert that these two 

had an overwhelming influence upon the CNA (2007) report but rather appears to be attacking the 

integrity of all of the briefers through questioning these two individuals. Presumably, in the commenter’s 

first criticism of an individual briefer, the individual in question is Anthony Janetos (commenter referred 

to an “Anthony Melillo”), and that criticism is based upon two issues: Dr. Janetos having co-chaired the 

National Assessment Synthesis Team for the U.S. Global Change Research Program report Climate 

10 
Change Impacts on the United States, published in 2000; and that his briefing would have been based 

upon the same science as in the IPCC reports. EPA notes that the aforementioned USGCRP report has 

not been discredited and is a part of the body of peer-reviewed assessment literature. The commenter’s 

second criticism of a briefer, Dr. Hansen, appeared to be premised entirely on an issue with the IPCC 

itself. For response to comments on use of IPCC, CSSP, USGCRP, and NRC reports as the primary 

scientific basis for the TSD, please see Volume 1 of this Response to Comments document. Overall, we 

determine that the sources used in this section of the TSD are reliable and the best available for 

summarizing the potential natural security impacts of climate change. 

We have added the following text to the TSD for clarity: “As the discussion on the national security risks 

of climate change is limited in the assessment literature, this section relies upon the following sources: 

U.S. government-published or -funded analyses—including the 2009 assessment report Global Climate 

Change Impacts in the United States--and a report by the Center for Naval Analyses (CNA) Corporation. 

These sources are legitimate as they typically rely on the assessment literature for their underlying 

science.” 

Comment (8-21):

Several commenters state that specific aspects of the climate impacts evidence summarized in the TSD 

with respect to national security do not support the Administrator’s endangerment finding. 

Response (8-21):

The specific issues that underlie these comments are addressed in the responses throughout this volume, 

and other volumes of the Response to Comments document. With regard to the commenters' conclusion 

that the current science does not support an endangerment finding with respect to national security, we 

disagree based on the scientific evidence before the Administrator. See the Findings, Section IV.B, “The 

Air Pollution is Reasonably Anticipated to Endanger Both Public Health and Welfare,” for details on how 

the Administrator weighed the scientific evidence underlying her endangerment determination in general, 

and with regard to the national security sector in particular. 

Comment (8-22):

One commenter (3702.1) believes that inherent assumptions about human behavior and adaptive capacity 

are embodied within the projected indirect national security impacts, and this is contradictory to EPA’s 

position not to include consideration of adaptive capacity in the Findings. 

Response (8-22):

See the Findings, Section III.C, “Adaptation and Mitigation,” for our response to comments on the 

treatment of adaptation and mitigation in the Findings. 

Comment (8-23):

A commenter (3702.1) believes that it is “inappropriate for EPA to assume that the U.S. agencies in 

charge of overseeing national security will fail to fulfill their function or that third parties will act 

unlawfully—under either domestic, foreign, or international law—in order to justify an endangerment 

finding.” 

Response (8-23):

We are not assuming that U.S. agencies in charge of overseeing national security will fail to fulfill their 

function. The TSD summarizes the potential national security impacts of climate change, which in turn 

11 
may require action by the U.S. government. It makes no judgment about any specific future action 

occurring, succeeding, or failing. With respect to the commenter’s second point, EPA is not assuming 

specific unlawful actions will occur. We are summarizing findings of reports prepared by experts 

regarding the implications of climate change on our national security and broadly discussing how climate 

change may contribute to, for example, political instability. Nowhere in this discussion does EPA make 

any assumptions of specific unlawful actions. We also note that EPA is not alone in recognizing the 

importance of the issue. As noted in the TSD, the U.S. Congress and the Department of Defense 

recognize and have taken action to assess the implications of climate change on national security. 

Comment (8-24):

A commenter (3702.1) states that if potential national security impacts are used to justify an 

endangerment finding, then additional national security impacts must be considered, including the 

secondary impacts of mitigation measures and policies. The commenter quotes the testimony of Dr. 

Fingar (Fingar, 2008) in stating that GHG reduction policies “may affect U.S. national security interest 

even more than the physical impacts of climate change itself.” The commenter (3702.1) also states that 

mitigation policies 

may contribute to or exacerbate international conflicts by, for example, raising food 

prices (one consequence of biofuel mandates already witnessed); causing relocation of 

manufacturing activity to unstable countries; sparking trade wars as a result of taxes or 

tariffs intended to discriminate against energy intensive products; and increasing energy 

prices around the world, which will likely slow economic growth in unstable countries. 

The commenter further states that EPA does not weigh the potential impacts of climate change with the 

“foreseeable climate change responses.” 

Response (8-24):

First, it is important to note that the commenter mischaracterizes Dr. Fingar’s testimony (Fingar, 2008). 

The full quoted sentence from his testimony reads as follows: 

Government, business, and public efforts to develop mitigation and adaptation strategies 

to deal with climate change—from policies to reduce greenhouse gases to plans to reduce 

exposure to climate change or capitalize on potential impacts—may affect US national 

security interests even more than the physical impacts of climate change itself. 

Thus, Dr. Fingar’s statement refers to adaptation and mitigation measures as well as strategies to 

capitalize on potential (presumably beneficial) impacts—not mitigation, or GHG reduction, policies only 

as the commenter asserted. 

In a broader sense, EPA is not aware of any instance in the peer-reviewed assessment literature where it is 

stated that national security impacts could be minimized by not taking any mitigation action—which 

appears to be what the commenter is implying. We note that the commenter did not submit or cite any 

literature to support this assertion. By way of an example of the current consensus, the report CNA 

(2007) cited in the TSD, in addition to describing projected impacts to national security from climate 

change, makes numerous recommendations for action (including mitigation and adaptation efforts) to 

reduce these projected national security impacts. EPA therefore does not find support for the 

commenter’s implication that we should assume that the secondary effects of mitigation measures and 

policies would be worse than the projected national security impacts in the absence of such actions. 

12 
Finally, with regard to the commenter’s request that we weigh the potential impacts of climate change 

with the foreseeable responses, see the Findings, Section III.C, “Adaptation and Mitigation,” for our 

response to comments on and treatment of adaptation and mitigation in the Findings. 

Comment (8-25): 

Several commenters (1529, 1564, 2147) state their support for the Findings, noting the threat of increased 

world conflict due to drought, crop impacts, and population displacement. One of these commenters 

(2147) shares his experience of living in the Sahel Region of Niger, West Africa, including the 

devastating effects of seasonal fluctuations on food security, access to clean water, prevalence of disease, 

and infant mortality, citing relevant concerns about potentially more severe impacts from global warming. 

One commenter (3062) notes that climate change will be a national security, public health, and social 

justice problem, not just environmental. One commenter (2818) states that climate change threats to 

security also pose a “very grave risk to our health.” The commenter further asserts that environmental 

resources are very likely to become scarcer as climate changes, which will pose both global security 

threats as well as security threats to the United States. 

Response (8-25):

We agree with the commenters that the literature states that projected impacts of climate change may pose 

a threat to U.S. national security. We note that the Administrator considered these issues as part of the 

endangerment finding; see Section IV.B, “The Air Pollution is Reasonably Anticipated to Endanger Both 

Public Health and Welfare,” of the Findings. 

We also agree that some of the national security threats that climate change may be a contributor to 

include resource scarcity and public health threats. As stated in Fingar (2008): 

From a national security perspective, climate change has the potential to affect lives (for 

example, through food and water shortages, increased health problems including the 

spread of disease, and increased potential for conflict), property (for example through 

ground subsidence, flooding, coastal erosion, and extreme weather events), and other 

security interests. 

8.3 Impacts in Other World Regions 

Comment (8-26): 

One commenter (3394.1) argues that EPA’s analysis of the international impacts of climate change is 

“wholly unscientific” and cannot, therefore, provide support for a positive endangerment finding. The 

commenter makes three arguments to support this. First, the commenter states that climate change 

impacts to foreign nations are “not directly relevant to an endangerment assessment.” Second, the 

commenter states: “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’.” Finally, the commenter criticizes the sources used for the TSD’s 

discussion of the national security impacts of climate change. 

Response (8-26):

Section 16 of the TSD relies on the latest USGCRP assessment report, Karl et al. (2009), multiple 

chapters of the IPCC Fourth Assessment Report, published studies on the national security implications of 

climate change, and expert testimony. Like the rest of the TSD, it provides references for each major 

13 
conclusion. Subsection 16(b), an overview of the projected international impacts associated with elevated 

atmospheric GHG concentrations, is based primarily on the IPCC Fourth Assessment Report and includes 

multiple references to eight separate chapters from the report, each of which synthesize hundreds of 

individual studies. See Section III.A., “The Science on Which the Decisions Are Based,” for our response 

to comments on the use of the assessment literature and our treatment of new and additional scientific 

literature provided through the public comment process. 

With regard to the commenter’s first argument, please see Volume 9 of this Response to Comments 

document for our response to comments regarding the global and domestic scope of the endangerment 

finding. Please see Section III.D, “Geographic Scope of Impacts,” and Section IV.B.2., “The Air 

Pollution Is Reasonably Anticipated to Endanger Public Welfare,” of the Findings for our response to 

broader legal and policy comments raised regarding international impacts. 

With regard to the second argument, we disagree that the foreign effects of climate change are not 

relevant to the United States, and we also disagree that the TSD failed to adequately demonstrate their 

relevance. The body of literature summarized in the TSD provides compelling evidence that climate 

change poses serious risks for other world regions, especially those that face greater impacts because they 

are more vulnerable. It also provides evidence that impacts of climate change in other world regions 

could, in turn, create economic, trade, humanitarian, and national security issues for the United States. 

We further note that we have revised the TSD to include the findings of the recently published USGCRP 

synthesis report (Karl et al. 2009), which further confirm these concerns. The report states (and the TSD 

now includes) the following, with respect to effects due to climate change impacts in other world regions: 

Meeting the challenge of improving conditions for the world’s poor has economic 

implications for the United States, as does intervention and resolution of intra- and 

intergroup conflicts. Where climate change exacerbates such challenges, for example by 

limiting access to scarce resources or increasing incidence of damaging weather events, 

consequences are likely for the U.S. economy and security. 

With respect to international trade and migration, we note that the TSD quotation referenced by the 

commenter does not state that international trade and migration patterns will not be affected by climate 

change. Rather, it states that there is currently a lack of information about precisely how they may be 

affected. The fact that we cannot with current tools project exactly how international trade and migration 

will be affected by climate change does not imply that they can not or will not be significantly affected. 

To further clarify the likelihood that climate change could affect trade and migration, we have added the 

following paragraph to the TSD: 

While there is currently a lack of information about how, precisely, impacts due to 

climate change may influence international trade and migration patterns, there is 

considerable evidence that they will be affected. The USGCRP (Karl et al., 2009) has 

concluded that the numbers of people wanting to immigrate to the United States will 

increase as conditions worsen elsewhere and that climate change has the potential to alter 

trade relationships by changing the comparative trade advantages of regions or nations. 

Shifts in both trade and migration can have multiple causes and the direct cause of 

potential increased migration, such as extreme climatic events, will be difficult to 

separate from other forces that drive people to migrate (USGCRP, 2009). 

Based upon this, we find that climate change impacts in foreign countries can clearly impact the United 

States through international trade and migration. The discussion of international impacts in the TSD is 

reasonable and accurately reflects the literature. 

14 
With regard to the commenter’s third argument, please see Section 8.2 of this volume for our response to 

comments regarding the national security impacts of climate change. 

Comment (8-27): 

One commenter (5844) states that the proposed finding “largely glosses over and ignores a tremendous 

list of impacts to human health and welfare around the globe... Food shortages, drought, mass migration, 

war, rising seas, threats to trade, economic dislocations, global pandemics, and increased weather 

disasters offer a short list of international vectors for indirect impacts on U.S. health and welfare.” The 

commenter asserts that impacts in other world regions should be fully enumerated and evaluated in order 

to estimate the indirect impacts to the United States of climate change affecting other nations, which 

alone “would satisfy the [Clean Air Act’s] human health and welfare tests for endangerment.” 

Response (8-27): 

We agree that numerous international impacts are projected to occur as a result of climate change, and 

that indirect impacts to the United States may result. We describe these projected impacts in Section 16 of 

the TSD. For example, the TSD quotes Karl et al. (2009) in stating that: 

In an increasingly interdependent world, U.S. vulnerability to climate change is linked to 

the fates of other nations. For examples, conflicts or mass migrations of people resulting 

from food scarcity and other resource limits, health impacts, or environmental stresses in 

other parts of the world could threaten U.S. national security. 

Please see Section IV.B.2.h, “Impacts in Other World Regions that Can Affect the U.S Population,” for a 

description of EPA’s consideration of international impacts in the finding. 

Comment (8-28):

Several commenters state that specific aspects of the climate impacts evidence summarized in the TSD 

with respect to impacts in other world regions do not support the Administrator’s endangerment finding. 

Response (8-28):

The specific issues that underlie these comments are addressed in the responses throughout this volume, 

and other volumes of the Response to Comments document. With regard to the commenters' conclusion 

that the current science does not support an endangerment finding with respect to impacts in other world 

regions, we disagree based on the scientific evidence before the Administrator. See the Findings, Section 

IV.B, “The Air Pollution is Reasonably Anticipated to Endanger Both Public Health and Welfare,” for 

details on how the Administrator weighed the scientific evidence underlying her endangerment 

determination in general, and with regard to the impacts in other world regions sector in particular. 

Comment (8-29): 

A commenter (3440.1) argues that EPA said the Ganges delta will be affected by rising sea levels but 

failed to point out that the land area of Bangladesh, on the Ganges delta, has increased by 70,000 square 

kilometers (sq. km) over the past 30 years, suggesting that sea level is not rising much there. The 

commenter further argued as follows: “You [the EPA] say that ‘global warming’ has been described as a 

‘national-security threat-multiplier’. How can it be, when there has not been any statistically significant 

‘global warming’ for 15 years, and when - on the calculations we have already outlined - there is no 

15 
reason to suppose that there will be any significant ‘global warming’ from anthropogenic causes in the 

future?” 

Response (8-29): 

The commenter did not provide a reference for the claim that the land area of Bangladesh has increased 

by 70,000 sq. km in the past years, and we were not able to confirm this number in a peer-reviewed 

assessment. However, Nicholls and Goodbred (2004) note that the observational database for the delta is 

poor and that a number of important questions about the delta evolution and the relative roles of natural 

and anthropogenic subsidence and sedimentation remain to be resolved. 

Even if the size of the Ganges delta had increased in size over the past 30 years, it would not 

automatically follow that “sea level is not rising much there” because potential changes in sedimentation 

could temporarily counteract the effects of sea level rise in some areas. According to the IPCC, sea level 

rise along the East Asia coast has been geographically variable but uniformly positive, with rates ranging 

from 1.5 to 4.4 millimeters per year (mm/yr) (Cruz et al., 2007). Cruz et al. (2007) further notes that 

climate change and sea level rise will tend to worsen the currently eroding coasts; that projected sea level 

rise could flood the residence of millions of people living in the low-lying areas of South, Southeast, and 

East Asia, such as in Bangladesh; and that even under the most conservative scenario, sea level will be 

about 40 centimeters (cm) higher than today by the end of the 21st century, which is projected to increase 

the annual number of people flooded in coastal populations from 13 million to 94 million. The GangesBrahmaputra delta has the largest population of 40 deltas identified worldwide, with over 1 million people 

at risk of being potentially displaced and directly affected by current sea level trends by 2050 (Cruz et al., 

2007). 

Please see Volume 2 of this Response to Comments document for our response to comments on observed 

temperature change. Please see Volume 3 of this Response to Comments document for our response to 

comments on attribution. Please see Volume 4 of this Response to Comments document for our response 

to comments on future projections of temperature change. 

Comment (8-30): 

A commenter (2876) expresses support for the findings and notes that climate change and high 

temperatures limit the amount of water available to residents of low-income countries, resulting in human 

and animal deaths. 

Response (8-30): 

We agree that water stress is projected to occur in some areas, including numerous developing countries, 

as a result of climate change, and describe this threat in Section 16 of the TSD. Please see Section 

IV.B.2.h, “Impacts in Other World Regions that Can Affect the U.S Population,” for a description of 

EPA’s consideration of international impacts in the Findings. 

Comment (8-31): 

Several commenters (0731, 3461.1, 4817, 11427) voice their support for EPA’s Proposed Findings due to 

concern about environmental refugees, or people that are displaced by catastrophic weather events. The 

commenters believe the numbers of environmental refugees will increase, putting pressure on limited 

local resources. One commenter estimated that rising sea levels will displace hundreds of millions of 

people in other regions worldwide such as Bangladesh, Philippines, Indonesia, Pakistan, India, the 

Egyptian Nile Delta, and the Brazilian Amazon Basin. 

16 
Response (8-31): 

We agree with the commenters that increased migration may result from climate change. We have revised 

the TSD to include the following statement from Karl et al. (2009) regarding migration impacts on the 

U.S., including national security impacts: 

In an increasingly interdependent world, U.S. vulnerability to climate change is linked to 

the fates of other nations. For examples, conflicts or mass migrations of people resulting 

from food scarcity and other resource limits, health impacts, or environmental stresses in 

other parts of the world could threaten U.S. national security. 

We have also revised the TSD to include the following: 

The USGCRP (Karl et al., 2009) concluded that the number of people wanting to 

immigrate to the United States will increase as conditions worsen elsewhere, and that 

climate change has the potential to alter trade relationships by changing the comparative 

trade advantages of regions or nations. Shifts in both trade and migration can have 

multiple causes and the direct cause of potential increased migration, such as extreme 

climatic events, will be difficult to separate from other forces that drive people to migrate 

(Karl et al., 2009). 

Please see Section IV.B.2.h, “Impacts in Other World Regions that Can Affect the U.S Population,” for a 

description of EPA’s consideration of international impacts in the Findings. 

8.4 Vulnerable Populations 

Comment (8-32): 

A number of commenters (e.g., 2818, 2895, 3195.1, 3338.1, 3402, 3422, 3895, 6809, 7021, 9450, 10126) 

point out that climate change disproportionately affects vulnerable populations. A commenter (3422), for 

example, states: “The impacts of climate change will be felt most acutely by those living in poverty and 

other vulnerable populations in the US and around the world.” Another commenter (7021) states that the 

elderly, infants, those with impaired health, the homeless, low-income people, and others who have 

limited access to health care and other resources are particularly vulnerable to extreme weather events. 

Some commenters provide reference documents to support their arguments regarding disproportionate 

impacts. A commenter (3338.1) references several studies (Morello-Frosch et al., 2009; GAO-05-289, 

2005; Jacobson, 2008) in support of a statement that EPA should find that GHGs endanger public health 

and welfare in part because of their adverse health and welfare impacts on poor and minority 

communities. Another commenter (3248) submits a paper (Costello et al., 2009) that focuses on managing 

the health effects of climate change and includes an analysis of impacts on vulnerable populations. 

 

Response (8-32): 

First, we note that climate change impacts vary significantly between and within regions on the basis of 

complex and interacting physical, economic, social, and political factors, such that particular groups that 

may experience disproportionate impacts in one area may not necessarily experience the same impacts in 

another. In general, however, we fully agree, and the assessment literature strongly supports, that certain 

vulnerable populations tend to experience disproportionate risks and impacts from climate change. 

Taken as a whole, the studies on observed and projected impacts of climate change synthesized in the 

assessment literature clearly indicate that the harmful effects of climate change will tend to fall most 

17 
heavily on certain parts of the population, both domestically and globally. The TSD summarizes this 

information, noting the following for the United States: 

 

The CCSP reports that climate change has the potential to accentuate the disparities already 

evident in the American health care systems, as many of the expected health effects are likely to 

fall disproportionately on the poor, the elderly, the disabled, and the uninsured. 

Within settlements experiencing climate change, certain parts of the population may be especially 

vulnerable; these include the poor, the elderly, those already in poor health, the disabled, those 

living alone, and/or indigenous populations dependent on one or few resources (Wilbanks et al., 

2008). Notably, vulnerable groups represent a more significant part of the total population in 

some regions and localities than others (Karl et al., 2009). 

EPA has reviewed the studies referenced by commenters to support their arguments regarding 

disproportionate impacts. We find that the studies referenced by commenters are directionally consistent 

with the assessment literature summarized in the TSD. EPA concludes that the TSD’s summary of the 

current state of the science on this topic as reflected in the assessment literature is reasonable and sound. 

Comment (8-33):

Many commenters (e.g., 2818, 2895, 3195.1, 3402, 3422, 3895, 6809, 7021, 9450, and 10126) state that 

the impacts of climate change on vulnerable populations demand action to reduce GHG emissions and 

protect vulnerable populations from harmful effects. A commenter (7021), for example, states that “[i]t is 

an ethical imperative that we do all we can now to protect those in our society who will be most 

vulnerable to climate change.” 

Response (8-33): 

See Section III.C, “Adaptation and Mitigation,” of the Findings for our response to comments on the 

treatment of adaptation and mitigation in the Findings. 

Comment (8-34): 

Two commenters (3195.1, 2895) focus specifically on threats posed by climate change to the well-being 

of Native American tribes. A commenter (2895), for example, asserts that the ability of Native American 

tribes to sustain their culture is severely threatened by climate change. The commenter states: “Their 

rights to traditional resources are fixed to their reservations, trust lands, and some federal lands. Tribal 

members cannot move to escape climate change without losing their rights to hunt, fish, track, harvest and 

gather, and losing their connections to their ancestors and ancient stories. And as they remain, climate 

change is pulling the ecological rug from under them.” Another commenter (3195.1) makes a similar 

point, stating: “The greenhouse gases referred to under the proposed findings—carbon dioxide, 

hydrofluorocarbons, methane, nitrous oxide, perfluorocarbons and sulfur hexafluoride—endanger public 

health and welfare, and in particular are highly injurious to the many tribal communities in our nation and 

the world.” These commenters state that responses to climate change should take these unique risks into 

account. 

Response (8-34): 

We agree that certain Native American tribes, particularly those who are dependent on one or a few 

natural resources, possess unique vulnerabilities to the risks of climate change (Karl et al., 2009; Field et 

al., 2007; ACIA, 2004). Impacts are summarized in the TSD and are part of the information the 

Administrator drew upon in her endangerment analysis. Regarding the comment about responses to 

climate change, please see Volume 11 of this Response to Comments document. 

18 
Comment (8-35): 

Several commenters (2895 and 6809) focus especially on the particular risks children face due to climate 

change. A commenter (2895), for example, states that children “are at greater exposure given their 

nervous systems and their time spent outdoors, their greater sensitivity to certain exposures from 

environmental toxins caused from climate change, and their dependency on caregivers for appropriate 

preparedness and response.” 

Response (8-35): 

For EPA’s responses to comments and literature provided on children’s health issues in the TSD, please 

see Volume 5 of the Response to Comment document. 

Comment (8-36): 

Several commenters state that it is important to consider the impacts of climate change on vulnerable 

populations in determining appropriate responses. A commenter (2895), for example, states: “We must 

consider the impacts on the poor and disenfranchised as we look for ways to respond to climate change.” 

A commenter (4154) states that socio-economic data for Council of Energy Resource members and other 

tribes shows that they are among the poorest populations in the U.S. and states: “It would be grossly 

inequitable to subject the Indian Tribes to a set of restrictions designed for an affluent, high greenhouse 

gas emission society when the Tribes are, in fact, more accurately analogized to a developing country. 

EPA should endeavor to design its regulatory program in a manner sensitive to these concerns so that 

Indian Tribes will be able to grow their economies and provide their members with a standard of living in 

parity with prevailing national averages.” 

Response (8-36): 

The issues raised by the commenters regarding the economic impacts of mitigation measures are not 

relevant to the endangerment determination, but would be addressed in other actions, as appropriate. See 

our response on this issue in Volume 11 of the Response to Comments document. 

Comment (8-37): 

Several commenters (3214.2, 3477, 3507.2, 4395, 5787, and 11047) state that EPA should not make an 

endangerment finding in part or in whole because such an action would disproportionately and adversely 

impact minorities, the poor, and/or indigenous populations. A commenter (3214.2), for example, states 

that based on its own careful analysis of this action and its likely impacts on American businesses, jobs, 

minorities, low- and fixed-income families, and others, EPA should not make an endangerment finding or 

promulgate these proposed rules because such an action would “have disproportionate impacts on 

minorities and would violate civil rights and accepted standards of science, economics and environmental 

justice.” Another commenter (3477) states: “Indigenous populations life expectancies continue to improve 

through their use of carbon based energy. Energy use allow for adaptation. Restricting energy usage 

through this endangerment finding will actually negatively impact the poor and indigenous populations to 

a greater degree.” 

Response (8-37): 

See Section III.C, “Adaptation and Mitigation,” of the Findings for our response to comments on the 

treatment of adaptation and mitigation in the Findings. The issues raised by the commenters regarding the 

economic impacts of mitigation measures are not relevant to the endangerment determination, but would 

be addressed in other potential actions, as appropriate. See Volume 11 of this Response to Comments 

19 
document with regard to the economic implications. Note that this action does not impose any standards, 

regulations or restrictions. 

Comment (8-38): 

Several commenters (1556, 1620, 1807, 3331, 3461.1, 3565.1, 3566.1, 3768, 3986, 7137, 8560, and 

11422) voice their support for EPA’s Proposed Findings on the grounds that global warming will not 

affect all people equally and may “exacerbate social and racial disparities.” The commenters cite a 

number of examples, including the sensitivity of children to pollutants and their reliance on others in 

extreme weather events, as well as the high risk to the elderly and the poor during extreme heat events. 

The commenters state that global warming will also disproportionally affect those that are unable to move 

away from areas where the effects of global warming are greatest, including individuals who live in 

coastal regions. Two commenters conclude that the “disproportionate and discriminatory impacts” on 

vulnerable populations make climate change one of the “most significant environmental justice issues of 

our time.” 

Response (8-38): 

We agree that climate change presents risks and impacts to certain vulnerable populations. See Volume 5 

of this Response to Comments document for EPA’s responses to comments on specific aspects of climate 

risks to public health. 

Comment (8-39): 

Commenter (3344.2) submits an 87-page report entitled As Goes the Arctic, So Goes the Planet (Karnik, 

2008) as evidence that climate change will disproportionately affect indigenous communities of Alaska 

and the Arctic. The report is also a formal petition to EPA for rulemaking under the Clean Air Act to 

regulate greenhouse gas emissions from mobile and stationary sources to protect the health and welfare of 

the Arctic and the world. 

Response (8-39): 

We have reviewed the report submitted by the commenter. The report states that climate change directly 

impairs the health and cultural identity of Arctic residents in numerous ways. We agree that climate 

change presents risks and impacts to certain vulnerable populations, including indigenous communities in 

Alaska. As we state in the Findings: “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 and cultural impacts on their historic lifestyles.” 

Regarding the commenter’s petition for rulemaking, this specific petition is not being addressed in these 

Findings. See Volume 5 of this Response to Comments document for EPA’s responses to comments on 

specific aspects of climate risks to public health. 

Comment (8-40): 

One commenter (3768) states that the “effects of climate change will be felt most significantly by the 

poor, contributing to political instability.” 

Response (8-40): 

We agree that climate change presents risks and impacts to certain vulnerable populations, and that 

climate change could contribute to political instability. As stated by CNA (2007) and quoted in the TSD: 

“Projected climate change will seriously exacerbate already marginal living standards in many Asian, 

20 
21 

African, and Middle Eastern nations, causing widespread political instability and the likelihood of failed 

states.” 

References 

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Health Commission: Managing the health effects of climate change. Lancet, 373: 1693 733. 

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Hanson, eds. Climate Change 2007: Impacts, Adaptation, and Vulnerability. Contribution of Working 

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Jacobson, M.Z. (2008). On the causal link between carbon dioxide and air pollution mortality. 

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Karnik, J. (2008). As Goes the Arctic, So Goes the Planet. Washington, DC: Oceana. 

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