OPINION OF THE COURT MASSACHUSETTS V. EPA 549 U. S. ____ (2007) SUPREME COURT OF THE UNITED STATES NO. 05-1120 MASSACHUSETTS, et al., PETITIONERS v. ENVIRON- MENTAL PROTECTION AGENCY et al.

															on writ of certiorari to the united states court of
appeals for the district of columbia circuit

															[April 2, 2007]

															   Justice Stevens delivered the
opinion of the Court.

															   A well-documented rise in global
temperatures has coincided with a significant increase in the
concentration of carbon dioxide in the atmosphere. Respected
scientists believe the two trends are related. For when carbon
dioxide is released into the atmosphere, it acts like the ceiling
of a greenhouse, trapping solar energy and retarding the escape of
reflected heat. It is therefore a species—the most important
species—of a “greenhouse gas.”

															   Calling global warming “the most pressing
environmental challenge of our time,”[ Footnote 1 ] a group of States,[ Footnote 2 ] local governments,[ Footnote 3 ] and private organizations,[ Footnote 4 ] alleged in a petition for certiorari
that the Environmental Protection Agency (EPA) has abdicated its
responsibility under the Clean Air Act to regulate the emissions of
four greenhouse gases, including carbon dioxide. Specifically,
petitioners asked us to answer two questions concerning the meaning
of §202(a)(1) of the Act: whether EPA has the statutory authority
to regulate greenhouse gas emissions from new motor vehicles; and
if so, whether its stated reasons for refusing to do so are
consistent with the statute.

															   In response, EPA, supported by 10 intervening
States[ Footnote 5 ] and six
trade associations,[ Footnote 6 ]
correctly argued that we may not address those two questions unless
at least one petitioner has standing to invoke our jurisdiction
under Article III of the Constitution. Notwithstanding the serious
character of that jurisdictional argument and the absence of any
conflicting decisions construing §202(a)(1), the unusual importance
of the underlying issue persuaded us to grant the writ. 548 U. S.
__ (2006).

															I

															   Section 202(a)(1) of the Clean
Air Act, as added by Pub. L. 89–272, §101(8), 79 Stat. 992, and as
amended by, inter alia , 84 Stat. 1690 and 91 Stat. 791, 42
U. S. C. §7521(a)(1), provides:

															“The [EPA] Administrator shall by regulation
prescribe (and from time to time revise) in accordance with the
provisions of this section, standards applicable to the emission of
any air pollutant from any class or classes of new motor vehicles
or new motor vehicle engines, which in his judgment cause, or
contribute to, air pollution which may reasonably be anticipated to
endanger public health or welfare … .”[ Footnote 7 ]

															The Act defines “air pollutant” to include “any air
pollution agent or combination of such agents, including any
physical, chemical, biological, radioactive … substance or matter
which is emitted into or otherwise enters the ambient air.”
§7602(g). “Welfare” is also defined broadly: among other things, it
includes “effects on … weather … and climate.” §7602(h).

															   When Congress enacted these provisions, the
study of climate change was in its infancy.[ Footnote 8 ] In 1959, shortly after the U. S. Weather
Bureau began monitoring atmospheric carbon dioxide levels, an
observatory in Mauna Loa, Hawaii, recorded a mean level of 316
parts per million. This was well above the highest carbon dioxide
concentration—no more than 300 parts per million—revealed in the
420,000-year-old ice-core record.[ Footnote 9 ] By the time Congress drafted §202(a)(1) in
1970, carbon dioxide levels had reached 325 parts per
million.[ Footnote 10 ]

															   In the late 1970’s, the Federal Government
began devoting serious attention to the possibility that carbon
dioxide emissions associated with human activity could provoke
climate change. In 1978, Congress enacted the National Climate
Program Act, 92 Stat. 601, which required the President to
establish a program to “assist the Nation and the world to
understand and respond to natural and man-induced climate processes
and their implications,” id., §3. President Carter, in
turn, asked the National Research Council, the working arm of the
National Academy of Sciences, to investigate the subject. The
Council’s response was unequivocal: “If carbon dioxide continues to
increase, the study group finds no reason to doubt that climate
changes will result and no reason to believe that these changes
will be negligible… . A wait-and-see policy may mean waiting
until it is too late.”[ Footnote
11 ]

															   Congress next addressed the issue in 1987,
when it enacted the Global Climate Protection Act, Title XI of Pub.
L. 100–204, 101 Stat. 1407, note following 15 U. S. C. §2901.
Finding that “manmade pollution—the release of carbon dioxide,
chlorofluorocarbons, methane, and other trace gases into the
atmosphere—may be producing a long-term and substantial increase in
the average temperature on Earth,” §1102(1), 101 Stat. 1408,
Congress directed EPA to propose to Congress a “coordinated
national policy on global climate change,” §1103(b), and ordered
the Secretary of State to work “through the channels of
multilateral diplomacy” and coordinate diplomatic efforts to combat
global warming, §1103(c). Congress emphasized that “ongoing
pollution and deforestation may be contributing now to an
irreversible process” and that “[n]ecessary actions must be
identified and implemented in time to protect the climate.”
§1102(4).

															   Meanwhile, the scientific understanding of
climate change progressed. In 1990, the Intergovernmental Panel on
Climate Change (IPCC), a multinational scientific body organized
under the auspices of the United Nations, published its first
comprehensive report on the topic. Drawing on expert opinions from
across the globe, the IPCC concluded that “emissions resulting from
human activities are substantially increasing the atmospheric
concentrations of … greenhouse gases [which] will enhance the
greenhouse effect, resulting on average in an additional warming of
the Earth’s surface.”[ Footnote
12 ]

															   Responding to the IPCC report, the United
Nations convened the “Earth Summit” in 1992 in Rio de Janeiro. The
first President Bush attended and signed the United Nations
Framework Convention on Climate Change (UNFCCC), a nonbinding
agreement among 154 nations to reduce atmospheric concentrations of
carbon dioxide and other greenhouse gases for the purpose of
“prevent[ing] dangerous anthropogenic [ i.e. ,
human-induced] interference with the [Earth’s] climate
system.”[ Footnote 13 ] S.
Treaty Doc. No. 102–38, Art. 2, p. 5 (1992). The Senate
unanimously ratified the treaty.

															   Some five years later—after the IPCC issued a
second comprehensive report in 1995 concluding that “[t]he balance
of evidence suggests there is a discernible human influence on
global climate”[ Footnote
14 ]—the UNFCCC signatories met in Kyoto, Japan, and adopted a
protocol that assigned mandatory targets for industrialized nations
to reduce greenhouse gas emissions. Because those targets did not
apply to developing and heavily polluting nations such as China and
India, the Senate unanimously passed a resolution expressing its
sense that the United States should not enter into the Kyoto
Protocol. See S. Res. 98, 105th Cong., 1st Sess. (July 25, 1997)
(as passed). President Clinton did not submit the protocol to the
Senate for ratification.

															II

															   On October 20, 1999, a group of
19 private organizations[ Footnote 15 ] filed a rulemaking petition asking EPA to
regulate “greenhouse gas emissions from new motor vehicles under
§202 of the Clean Air Act.” App. 5. Petitioners maintained that
1998 was the “warmest year on record”; that carbon dioxide,
methane, nitrous oxide, and hydrofluorocarbons are “heat trapping
greenhouse gases”; that greenhouse gas emissions have significantly
accelerated climate change; and that the IPCC’s 1995 report warned
that “carbon dioxide remains the most important contributor to
[man-made] forcing of climate change.” Id., at 13
(internal quotation marks omitted). The petition further alleged
that climate change will have serious adverse effects on human
health and the environment. Id., at 22–35. As to EPA’s
statutory authority, the petition observed that the agency itself
had already confirmed that it had the power to regulate carbon
dioxide. See id., at 18, n. 21. In 1998, Jonathan Z.
Cannon, then EPA’s General Counsel, prepared a legal opinion
concluding that “CO 2 emissions are within the
scope of EPA’s authority to regulate,” even as he recognized that
EPA had so far declined to exercise that authority. Id., at 54 (memorandum to Carol M. Browner, Administrator (Apr. 10,
1998) (hereinafter Cannon memorandum)). Cannon’s successor, Gary S.
Guzy, reiterated that opinion before a congressional committee just
two weeks before the rulemaking petition was filed. See id., at 61. Fifteen months
after the petition’s submission, EPA requested public comment on
“all the issues raised in [the] petition,” adding a “particular”
request for comments on “any scientific, technical, legal, economic
or other aspect of these issues that may be relevant to EPA’s
consideration of this petition.” 66 Fed. Reg. 7486, 7487 (2001).
EPA received more than 50,000 comments over the next five months.
See 68 Fed. Reg. 52924 (2003). Before the close of the
comment period, the White House sought “assistance in identifying
the areas in the science of climate change where there are the
greatest certainties and uncertainties” from the National Research
Council, asking for a response “as soon as possible.” App. 213. The
result was a 2001 report titled Climate Change: An Analysis of Some
Key Questions (NRC Report), which, drawing heavily on the 1995 IPCC
report, concluded that “[g]reenhouse gases are accumulating in
Earth’s atmosphere as a result of human activities, causing surface
air temperatures and subsurface ocean temperatures to rise.
Temperatures are, in fact, rising.” NRC Report 1. On September 8, 2003, EPA
entered an order denying the rulemaking petition. 68 Fed. Reg.
52922. The agency gave two reasons for its decision: (1) that
contrary to the opinions of its former general counsels, the Clean
Air Act does not authorize EPA to issue mandatory regulations to
address global climate change, see id., at 52925–52929;
and (2) that even if the agency had the authority to set greenhouse
gas emission standards, it would be unwise to do so at this time, id., at 52929–52931. In concluding that it lacked
statutory authority over greenhouse gases, EPA observed that
Congress “was well aware of the global climate change issue when it
last comprehensively amended the [Clean Air Act] in 1990,” yet it
declined to adopt a proposed amendment establishing binding
emissions limitations. Id., at 52926. Congress instead
chose to authorize further investigation into climate change. Ibid. (citing §§103(g) and 602(e) of the Clean Air Act
Amendments of 1990, 104 Stat. 2652, 2703, 42 U. S. C.
§§7403(g)(1) and 7671a(e)). EPA further reasoned that Congress’
“specially tailored solutions to global atmospheric issues,” 68
Fed. Reg. 52926—in particular, its 1990 enactment of a
comprehensive scheme to regulate pollutants that depleted the ozone
layer, see Title VI, 104 Stat. 2649, 42 U. S. C.
§§7671–7671q—counseled against reading the general authorization of
§202(a)(1) to confer regulatory authority over greenhouse
gases. EPA stated that it was “urged
on in this view” by this Court’s decision in FDA v. Brown & Williamson Tobacco Corp., 529 U. S. 120 (2000). In that case,
relying on “tobacco[’s] unique political history,” id., at
159, we invalidated the Food and Drug Administration’s reliance on
its general authority to regulate drugs as a basis for asserting
jurisdiction over an “industry constituting a significant portion
of the American economy,” ibid . EPA reasoned that climate
change had its own “political history”: Congress designed the
original Clean Air Act to address local air pollutants
rather than a substance that “is fairly consistent in its
concentration throughout the world’s atmosphere,” 68 Fed.
Reg. 52927 (emphasis added); declined in 1990 to enact proposed
amendments to force EPA to set carbon dioxide emission standards
for motor vehicles, ibid. (citing H. R. 5966, 101st
Cong., 2d Sess. (1990)); and addressed global climate change in
other legislation, 68 Fed. Reg. 52927. Because of this political
history, and because imposing emission limitations on greenhouse
gases would have even greater economic and political repercussions
than regulating tobacco, EPA was persuaded that it lacked the power
to do so. Id., at 52928. In essence, EPA concluded that
climate change was so important that unless Congress spoke with
exacting specificity, it could not have meant the agency to address
it. Having reached that
conclusion, EPA believed it followed that greenhouse gases cannot
be “air pollutants” within the meaning of the Act. See ibid. (“It follows from this conclusion, that [greenhouse
gases], as such, are not air pollutants under the [Clean Air Act’s]
regulatory provisions …”). The agency bolstered this conclusion by
explaining that if carbon dioxide were an air pollutant, the only
feasible method of reducing tailpipe emissions would be to improve
fuel economy. But because Congress has already created detailed
mandatory fuel economy standards subject to Department of
Transportation (DOT) administration, the agency concluded that EPA
regulation would either conflict with those standards or be
superfluous. Id., at 52929. Even assuming that it had
authority over greenhouse gases, EPA explained in detail why it
would refuse to exercise that authority. The agency began by
recognizing that the concentration of greenhouse gases has
dramatically increased as a result of human activities, and
acknowledged the attendant increase in global surface air
temperatures. Id., at 52930. EPA nevertheless gave
controlling importance to the NRC Report’s statement that a causal
link between the two “ ‘cannot be unequivocally
established.’ ” Ibid. (quoting NRC Report 17). Given
that residual uncertainty, EPA concluded that regulating greenhouse
gas emissions would be unwise. 68 Fed. Reg. 52930. The agency furthermore
characterized any EPA regulation of motor-vehicle emissions as a
“piecemeal approach” to climate change, id., at 52931, and
stated that such regulation would conflict with the President’s
“comprehensive approach” to the problem, id., at 52932.
That approach involves additional support for technological
innovation, the creation of nonregulatory programs to encourage
voluntary private-sector reductions in greenhouse gas emissions,
and further research on climate change—not actual regulation. Id., at 52932–52933. According to EPA, unilateral EPA
regulation of motor-vehicle greenhouse gas emissions might also
hamper the President’s ability to persuade key developing countries
to reduce greenhouse gas emissions. Id., at
52931. III Petitioners, now
joined by intervenor States and local governments, sought review of
EPA’s order in the United States Court of Appeals for the District
of Columbia Circuit.[ Footnote
16 ] Although each of the three judges on the panel wrote a
separate opinion, two judges agreed “that the EPA Administrator
properly exercised his discretion under §202(a)(1) in denying the
petition for rule making.” 415 F. 3d 50, 58 (2005). The court
therefore denied the petition for review. In his opinion
announcing the court’s judgment, Judge Randolph avoided a
definitive ruling as to petitioners’ standing, id., at 56,
reasoning that it was permissible to proceed to the merits because
the standing and the merits inquiries “overlap[ped],” ibid . Assuming without deciding that the statute
authorized the EPA Administrator to regulate greenhouse gas
emissions that “in his judgment” may “reasonably be anticipated to
endanger public health or welfare,” 42 U. S. C. §7521(a)(1),
Judge Randolph concluded that the exercise of that judgment need
not be based solely on scientific evidence, but may also be
informed by the sort of policy judgments that motivate
congressional action. 415 F. 3d, at 58. Given that framework,
it was reasonable for EPA to base its decision on scientific
uncertainty as well as on other factors, including the concern that
unilateral regulation of U. S. motor-vehicle emissions could weaken
efforts to reduce greenhouse gas emissions from other countries. Ibid . Judge Sentelle wrote
separately because he believed petitioners failed to “demonstrat[e]
the element of injury necessary to establish standing under Article
III.” Id., at 59 (opinion dissenting in part and
concurring in judgment). In his view, they had alleged that global
warming is “harmful to humanity at large,” but could not allege
“particularized injuries” to themselves. Id., at 60
(citing Lujan v. Defenders of Wildlife , 504 U. S. 555 , 562
(1992)). While he dissented on standing, however, he accepted the
contrary view as the law of the case and joined Judge Randolph’s
judgment on the merits as the closest to that which he preferred.
415 F. 3d, at 60–61. Judge Tatel dissented.
Emphasizing that EPA nowhere challenged the factual basis of
petitioners’ affidavits, id., at 66, he concluded that at
least Massachusetts had “satisfied each element of Article III
standing—injury, causation, and redressability,” id., at
64. In Judge Tatel’s view, the “ ‘substantial
probability,’ ” id. , at 66, that projected rises in
sea level would lead to serious loss of coastal property was a “far
cry” from the kind of generalized harm insufficient to ground
Article III jurisdiction. Id., at 65. He found that
petitioners’ affidavits more than adequately supported the
conclusion that EPA’s failure to curb greenhouse gas emissions
contributed to the sea level changes that threatened Massachusetts’
coastal property. Ibid . As to redressability, he observed
that one of petitioners’ experts, a former EPA climatologist,
stated that “ ‘[a]chievable reductions in emissions of
CO 2 and other [greenhouse gases] from U. S. motor
vehicles would … delay and moderate many of the adverse impacts of
global warming.’ ” Ibid . (quoting declaration of
Michael MacCracken, former Executive Director, U. S. Global Change
Research Program ¶5(e) (hereinafter MacCracken Decl.), available in
2 Petitioners’ Standing Appendix in No. 03–1361, etc., (CADC),
p. 209 (Stdg. App.)). He further noted that the one-time
director of EPA’s motor-vehicle pollution control efforts stated in
an affidavit that enforceable emission standards would lead to the
development of new technologies that “ ‘would gradually be
mandated by other countries around the world.’ ” 415
F. 3d, at 66 (quoting declaration of Michael Walsh ¶¶7–8, 10,
Stdg. App. 309–310, 311). On the merits, Judge Tatel explained at
length why he believed the text of the statute provided EPA with
authority to regulate greenhouse gas emissions, and why its policy
concerns did not justify its refusal to exercise that authority.
415 F. 3d, at 67–82. IV Article III of the Constitution limits
federal-court jurisdiction to “Cases” and “Controversies.” Those
two words confine “the business of federal courts to questions
presented in an adversary context and in a form historically viewed
as capable of resolution through the judicial process.” Flast v. Cohen , 392 U. S. 83 , 95 (1968).
It is therefore familiar learning that no justiciable “controversy”
exists when parties seek adjudication of a political question, Luther v. Borden , 7 How. 1 (1849), when they ask
for an advisory opinion, Hayburn’s Case , 2 Dall. 409
(1792), see also Clinton v. Jones , 520 U. S. 681 , 700, n.
33 (1997), or when the question sought to be adjudicated has been
mooted by subsequent developments, California v. San
Pablo & Tulare R. Co. , 149 U. S. 308 (1893).
This case suffers from none of these defects. The parties’ dispute turns on the proper
construction of a congressional statute, a question eminently
suitable to resolution in federal court. Congress has moreover
authorized this type of challenge to EPA action. See 42 U.
S. C. §7607(b)(1). That authorization is of critical
importance to the standing inquiry: “Congress has the power to
define injuries and articulate chains of causation that will give
rise to a case or controversy where none existed before.” Lujan , 504 U. S., at 580 (Kennedy, J., concurring in part
and concurring in judgment). “In exercising this power, however,
Congress must at the very least identify the injury it seeks to
vindicate and relate the injury to the class of persons entitled to
bring suit.” Ibid. We will not, therefore, “entertain
citizen suits to vindicate the public’s nonconcrete interest in the
proper administration of the laws.” Id. , at
581. EPA
maintains that because greenhouse gas emissions inflict widespread
harm, the doctrine of standing presents an insuperable
jurisdictional obstacle. We do not agree. At bottom, “the gist of
the question of standing” is whether petitioners have “such a
personal stake in the outcome of the controversy as to assure that
concrete adverseness which sharpens the presentation of issues upon
which the court so largely depends for illumination.” Baker v. Carr , 369 U. S. 186 , 204
(1962). As Justice Kennedy explained in his Lujan concurrence: “While it does
not matter how many persons have been injured by the challenged
action, the party bringing suit must show that the action injures
him in a concrete and personal way. This requirement is not just an
empty formality. It preserves the vitality of the adversarial
process by assuring both that the parties before the court have an
actual, as opposed to professed, stake in the outcome, and that the
legal questions presented … will be resolved, not in the rarified
atmosphere of a debating society, but in a concrete factual context
conducive to a realistic appreciation of the consequences of
judicial action.” 504 U. S., at 581 (internal quotation marks
omitted). To ensure the proper adversarial
presentation, Lujan holds that a litigant must demonstrate
that it has suffered a concrete and particularized injury that is
either actual or imminent, that the injury is fairly traceable to
the defendant, and that it is likely that a favorable decision will
redress that injury. See id. , at 560–561. However, a
litigant to whom Congress has “accorded a procedural right to
protect his concrete interests,” id. , at 572, n. 7—here,
the right to challenge agency action unlawfully withheld,
§7607(b)(1)—“can assert that right without meeting all the normal
standards for redressability and immediacy,” ibid. When a
litigant is vested with a procedural right, that litigant has
standing if there is some possibility that the requested relief
will prompt the injury-causing party to reconsider the decision
that allegedly harmed the litigant. Ibid.; see also Sugar Cane Growers Cooperative of Fla. v. Veneman , 289 F. 3d 89, 94–95 (CADC 2002) (“A [litigant]
who alleges a deprivation of a procedural protection to which he is
entitled never has to prove that if he had received the procedure
the substantive result would have been altered. All that is
necessary is to show that the procedural step was connected to the
substantive result”). Only one of
the petitioners needs to have standing to permit us to consider the
petition for review. See Rumsfeld v. Forum for
Academic and Institutional Rights, Inc. , 547 U. S. 47 , 52,
n. 2 (2006). We stress here, as did Judge Tatel below, the
special position and interest of Massachusetts. It is of
considerable relevance that the party seeking review here is a
sovereign State and not, as it was in Lujan , a private
individual. Well before
the creation of the modern administrative state, we recognized that
States are not normal litigants for the purposes of invoking
federal jurisdiction. As Justice Holmes explained in Georgia v. Tennessee Copper Co. , 206 U. S. 230 , 237 (1907), a case in
which Georgia sought to protect its citizens from air pollution
originating outside its borders: “The case has been argued largely as if it
were one between two private parties; but it is not. The very
elements that would be relied upon in a suit between
fellow-citizens as a ground for equitable relief are wanting here.
The State owns very little of the territory alleged to be affected,
and the damage to it capable of estimate in money, possibly, at
least, is small. This is a suit by a State for an injury to it in
its capacity of quasi- sovereign. In that capacity the
State has an interest independent of and behind the titles of its
citizens, in all the earth and air within its domain. It has the
last word as to whether its mountains shall be stripped of their
forests and its inhabitants shall breathe pure
air.” Just as Georgia’s
“independent interest … in all the earth and air within its domain”
supported federal jurisdiction a century ago, so too does
Massachusetts’ well-founded desire to preserve its sovereign
territory today. Cf. Alden v. Maine , 527 U. S. 706 , 715
(1999) (observing that in the federal system, the States “are not
relegated to the role of mere provinces or political corporations,
but retain the dignity, though not the full authority, of
sovereignty”). That Massachusetts does in fact own a great deal of
the “territory alleged to be affected” only reinforces the
conclusion that its stake in the outcome of this case is
sufficiently concrete to warrant the exercise of federal judicial
power. When a State
enters the Union, it surrenders certain sovereign prerogatives.
Massachusetts cannot invade Rhode Island to force reductions in
greenhouse gas emissions, it cannot negotiate an emissions treaty
with China or India, and in some circumstances the exercise of its
police powers to reduce in-state motor-vehicle emissions might well
be pre-empted. See Alfred L. Snapp & Son, Inc. v. Puerto Rico ex rel. Barez , 458 U. S. 592 , 607 (1982) (“One
helpful indication in determining whether an alleged injury to the
health and welfare of its citizens suffices to give the State
standing to sue parens patriae is whether the injury is
one that the State, if it could, would likely attempt to address
through its sovereign lawmaking powers”). These
sovereign prerogatives are now lodged in the Federal Government,
and Congress has ordered EPA to protect Massachusetts (among
others) by prescribing standards applicable to the “emission of any
air pollutant from any class or classes of new motor vehicle
engines, which in [the Administrator’s] judgment cause, or
contribute to, air pollution which may reasonably be anticipated to
endanger public health or welfare.” 42 U. S. C. §7521(a)(1).
Congress has moreover recognized a concomitant procedural right to
challenge the rejection of its rulemaking petition as arbitrary and
capricious. §7607(b)(1). Given that procedural right and
Massachusetts’ stake in protecting its quasi-sovereign interests,
the Commonwealth is entitled to special solicitude in our standing
analysis.[ Footnote
17 ] With that in
mind, it is clear that petitioners’ submissions as they pertain to
Massachusetts have satisfied the most demanding standards of the
adversarial process. EPA’s steadfast refusal to regulate greenhouse
gas emissions presents a risk of harm to Massachusetts that is both
“actual” and “imminent.” Lujan , 504 U. S., at 560
(internal quotation marks omitted). There is, moreover, a
“substantial likelihood that the judicial relief requested” will
prompt EPA to take steps to reduce that risk. Duke Power
Co. v. Carolina Environmental Study Group, Inc. , 438 U. S. 59 , 79
(1978). The
Injury The harms associated with climate change
are serious and well recognized. Indeed, the NRC Report
itself—which EPA regards as an “objective and independent
assessment of the relevant science,” 68 Fed. Reg. 52930—identifies
a number of environmental changes that have already inflicted
significant harms, including “the global retreat of mountain
glaciers, reduction in snow-cover extent, the earlier spring
melting of rivers and lakes, [and] the accelerated rate of rise of
sea levels during the 20th century relative to the past few
thousand years … .” NRC Report 16. Petitioners allege that this only hints
at the environmental damage yet to come. According to the climate
scientist Michael MacCracken, “qualified scientific experts
involved in climate change research” have reached a “strong
consensus” that global warming threatens (among other things) a
precipitate rise in sea levels by the end of the century,
MacCracken Decl. ¶15, Stdg. App. 207, “severe and irreversible
changes to natural ecosystems,” id., ¶5(d), at 209, a
“significant reduction in water storage in winter snowpack in
mountainous regions with direct and important economic
consequences,” ibid. , and an increase in the spread of
disease, id., ¶28, at 218–219. He also observes that
rising ocean temperatures may contribute to the ferocity of
hurricanes. Id ., ¶¶23–25, at 216–217.[ Footnote 18 ] That these
climate-change risks are “widely shared” does not minimize
Massachusetts’ interest in the outcome of this litigation. See Federal Election Comm’n v. Akins , 524 U. S. 11 , 24 (1998)
(“[W]here a harm is concrete, though widely shared, the Court has
found ‘injury in fact’ ”). According to petitioners’
unchallenged affidavits, global sea levels rose somewhere between
10 and 20 centimeters over the 20th century as a result of global
warming. MacCracken Decl. ¶5(c), Stdg. App. 208. These rising seas
have already begun to swallow Massachusetts’ coastal land. Id., at 196 (declaration of Paul H. Kirshen ¶5), 216
(MacCracken Decl. ¶23). Because the Commonwealth “owns a
substantial portion of the state’s coastal property,” id., at 171 (declaration of Karst R. Hoogeboom ¶4),[ Footnote 19 ] it has alleged a particularized
injury in its capacity as a landowner. The severity of that injury
will only increase over the course of the next century: If sea
levels continue to rise as predicted, one Massachusetts official
believes that a significant fraction of coastal property will be
“either permanently lost through inundation or temporarily lost
through periodic storm surge and flooding events.” Id., ¶6, at 172.[ Footnote 20 ]
Remediation costs alone, petitioners allege, could run well into
the hundreds of millions of dollars. Id., ¶7, at 172; see
also Kirshen Decl. ¶12, at 198.[ Footnote 21 ] Causation EPA does not dispute the existence of a
causal connection between man-made greenhouse gas emissions and
global warming. At a minimum, therefore, EPA’s refusal to regulate
such emissions “contributes” to Massachusetts’
injuries. EPA nevertheless maintains that its
decision not to regulate greenhouse gas emissions from new motor
vehicles contributes so insignificantly to petitioners’ injuries
that the agency cannot be haled into federal court to answer for
them. For the same reason, EPA does not believe that any realistic
possibility exists that the relief petitioners seek would mitigate
global climate change and remedy their injuries. That is especially
so because predicted increases in greenhouse gas emissions from
developing nations, particularly China and India, are likely to
offset any marginal domestic decrease. But EPA
overstates its case. Its argument rests on the erroneous assumption
that a small incremental step, because it is incremental, can never
be attacked in a federal judicial forum. Yet accepting that premise
would doom most challenges to regulatory action. Agencies, like
legislatures, do not generally resolve massive problems in one fell
regulatory swoop. See Williamson v. Lee Optical of Okla.,
Inc. , 348 U. S.
483 , 489 (1955) (“[A] reform may take one step at a time,
addressing itself to the phase of the problem which seems most
acute to the legislative mind”). They instead whittle away at them
over time, refining their preferred approach as circumstances
change and as they develop a more-nuanced understanding of how best
to proceed. Cf. SEC v. Chenery Corp. , 332 U. S. 194 , 202
(1947) (“Some principles must await their own development, while
others must be adjusted to meet particular, unforeseeable
situations”). That a first step might be tentative does not by
itself support the notion that federal courts lack jurisdiction to
determine whether that step conforms to law. And reducing
domestic automobile emissions is hardly a tentative step. Even
leaving aside the other greenhouse gases, the United States
transportation sector emits an enormous quantity of carbon dioxide
into the atmosphere—according to the MacCracken affidavit, more
than 1.7 billion metric tons in 1999 alone. ¶30, Stdg. App. 219.
That accounts for more than 6% of worldwide carbon dioxide
emissions. Id., at 232 (Oppenheimer Decl. ¶3); see also
MacCracken Decl. ¶31, at 220. To put this in perspective:
Considering just emissions from the transportation sector, which
represent less than one-third of this country’s total carbon
dioxide emissions, the United States would still rank as the
third-largest emitter of carbon dioxide in the world, outpaced only
by the European Union and China.[ Footnote 22 ] Judged by any standard, U. S. motor-vehicle
emissions make a meaningful contribution to greenhouse gas
concentrations and hence, according to petitioners, to global
warming. The
Remedy While it may be true that regulating
motor-vehicle emissions will not by itself reverse global
warming, it by no means follows that we lack jurisdiction to decide
whether EPA has a duty to take steps to slow or reduce it. See also Larson v. Valente , 456 U. S. 228 ,
244, n. 15 (1982) (“[A] plaintiff satisfies the redressability
requirement when he shows that a favorable decision will relieve a
discrete injury to himself. He need not show that a favorable
decision will relieve his every injury”). Because of the
enormity of the potential consequences associated with man-made
climate change, the fact that the effectiveness of a remedy might
be delayed during the (relatively short) time it takes for a new
motor-vehicle fleet to replace an older one is essentially
irrelevant.[ Footnote 23 ] Nor
is it dispositive that developing countries such as China and India
are poised to increase greenhouse gas emissions substantially over
the next century: A reduction in domestic emissions would slow the
pace of global emissions increases, no matter what happens
elsewhere. We moreover attach considerable significance
to EPA’s “agree[ment] with the President that ‘we must address the
issue of global climate change,’ ” 68 Fed. Reg. 52929 (quoting
remarks announcing Clear Skies and Global Climate Initiatives, 2002
Public Papers of George W. Bush, Vol. 1, Feb. 14, p. 227
(2004)), and to EPA’s ardent support for various voluntary
emission-reduction programs, 68 Fed. Reg. 52932. As Judge Tatel
observed in dissent below, “EPA would presumably not bother with
such efforts if it thought emissions reductions would have no
discernable impact on future global warming.” 415 F. 3d, at
66. In sum—at
least according to petitioners’ uncontested affidavits—the rise in
sea levels associated with global warming has already harmed and
will continue to harm Massachusetts. The risk of catastrophic harm,
though remote, is nevertheless real. That risk would be reduced to
some extent if petitioners received the relief they seek. We
therefore hold that petitioners have standing to challenge the
EPA’s denial of their rulemaking petition.[ Footnote 24 ] V The scope of our review of the merits of the
statutory issues is narrow. As we have repeated time and again, an
agency has broad discretion to choose how best to marshal its
limited resources and personnel to carry out its delegated
responsibilities. See Chevron U. S. A. Inc. v. Natural Resources Defense Council, Inc. , 467
U. S. 837 , 842–845 (1984). That discretion is at its height
when the agency decides not to bring an enforcement action.
Therefore, in Heckler v. Chaney , 470 U. S. 821 (1985), we
held that an agency’s refusal to initiate enforcement proceedings
is not ordinarily subject to judicial review. Some debate remains,
however, as to the rigor with which we review an agency’s denial of
a petition for rulemaking. There are key differences between a denial
of a petition for rulemaking and an agency’s decision not to
initiate an enforcement action. See American Horse Protection
Assn., Inc. v. Lyng , 812 F. 2d 1, 3–4 (CADC 1987). In
contrast to nonenforcement decisions, agency refusals to initiate
rulemaking “are less frequent, more apt to involve legal as opposed
to factual analysis, and subject to special formalities, including
a public explanation.” Id. , at 4; see also 5 U. S. C.
§555(e). They moreover arise out of denials of petitions for
rulemaking which (at least in the circumstances here) the affected
party had an undoubted procedural right to file in the first
instance. Refusals to promulgate rules are thus susceptible to
judicial review, though such review is “extremely limited” and
“highly deferential.” National Customs Brokers & Forwarders
Assn of America, Inc. v. United States , 883 F. 2d 93,
96 (CADC 1989). EPA
concluded in its denial of the petition for rulemaking that it
lacked authority under 42 U. S. C. §7521(a)(1) to regulate new
vehicle emissions because carbon dioxide is not an “air pollutant”
as that term is defined in §7602. In the alternative, it concluded
that even if it possessed authority, it would decline to do so
because regulation would conflict with other administration
priorities. As discussed earlier, the Clean Air Act expressly
permits review of such an action. §7607(b)(1). We therefore “may
reverse any such action found to be … arbitrary, capricious, an
abuse of discretion, or otherwise not in accordance with law.”
§7607(d)(9). VI On the merits, the first question is whether
§202(a)(1) of the Clean Air Act authorizes EPA to regulate
greenhouse gas emissions from new motor vehicles in the event that
it forms a “judgment” that such emissions contribute to climate
change. We have little trouble concluding that it does. In relevant
part, §202(a)(1) provides that EPA “shall by regulation prescribe …
standards applicable to the emission of any air pollutant from any
class or classes of new motor vehicles or new motor vehicle
engines, which in [the Administrator’s] judgment cause, or
contribute to, air pollution which may reasonably be anticipated to
endanger public health or welfare.” 42 U. S. C. §7521(a)(1).
Because EPA believes that Congress did not intend it to regulate
substances that contribute to climate change, the agency maintains
that carbon dioxide is not an “air pollutant” within the meaning of
the provision. The statutory text forecloses EPA’s reading.
The Clean Air Act’s sweeping definition of “air pollutant” includes
“ any air pollution agent or combination of such agents,
including any physical, chemical … substance or matter
which is emitted into or otherwise enters the ambient
air … .” §7602(g) (emphasis added). On its face, the
definition embraces all airborne compounds of whatever stripe, and
underscores that intent through the repeated use of the word
“any.”[ Footnote 25 ] Carbon
dioxide, methane, nitrous oxide, and hydrofluorocarbons are without
a doubt “physical [and] chemical … substance[s] which [are] emitted
into … the ambient air.” The statute is unambiguous.[ Footnote 26 ] Rather than
relying on statutory text, EPA invokes postenactment congressional
actions and deliberations it views as tantamount to a congressional
command to refrain from regulating greenhouse gas emissions. Even
if such postenactment legislative history could shed light on the
meaning of an otherwise-unambiguous statute, EPA never identifies
any action remotely suggesting that Congress meant to curtail its
power to treat greenhouse gases as air pollutants. That subsequent
Congresses have eschewed enacting binding emissions limitations to
combat global warming tells us nothing about what Congress meant
when it amended §202(a)(1) in 1970 and 1977.[ Footnote 27 ] And unlike EPA, we have no
difficulty reconciling Congress’ various efforts to promote
interagency collaboration and research to better understand climate
change[ Footnote 28 ] with the
agency’s pre-existing mandate to regulate “any air pollutant” that
may endanger the public welfare. See 42 U. S. C. §7601(a)(1).
Collaboration and research do not conflict with any thoughtful
regulatory effort; they complement it.[ Footnote 29 ] EPA’s
reliance on Brown & Williamson Tobacco Corp. , 529 U. S. 120 , is similarly misplaced.
In holding that tobacco products are not “drugs” or “devices”
subject to Food and Drug Administration (FDA) regulation pursuant
to the Food, Drug and Cosmetic Act (FDCA), see 529 U. S., at 133,
we found critical at least two considerations that have no
counterpart in this case. First, we
thought it unlikely that Congress meant to ban tobacco products,
which the FDCA would have required had such products been
classified as “drugs” or “devices.” Id., at 135–137. Here,
in contrast, EPA jurisdiction would lead to no such extreme
measures. EPA would only regulate emissions, and even
then, it would have to delay any action “to permit the development
and application of the requisite technology, giving appropriate
consideration to the cost of compliance,” §7521(a)(2). However much
a ban on tobacco products clashed with the “common sense” intuition
that Congress never meant to remove those products from
circulation, Brown & Williamson , 529 U. S., at
133 , there is nothing counterintuitive to the notion that
EPA can curtail the emission of substances that are putting the
global climate out of kilter. Second, in Brown & Williamson we pointed to an unbroken series of
congressional enactments that made sense only if adopted “against
the backdrop of the FDA’s consistent and repeated statements that
it lacked authority under the FDCA to regulate tobacco.” Id. , at 144. We can point to no such enactments here: EPA
has not identified any congressional action that conflicts in any
way with the regulation of greenhouse gases from new motor
vehicles. Even if it had, Congress could not have acted against a
regulatory “backdrop” of disclaimers of regulatory authority. Prior
to the order that provoked this litigation, EPA had never disavowed
the authority to regulate greenhouse gases, and in 1998 it in fact
affirmed that it had such authority. See App. 54 (Cannon
memorandum). There is no reason, much less a compelling reason, to
accept EPA’s invitation to read ambiguity into a clear
statute. EPA finally
argues that it cannot regulate carbon dioxide emissions from motor
vehicles because doing so would require it to tighten mileage
standards, a job (according to EPA) that Congress has assigned to
DOT. See 68 Fed. Reg. 52929. But that DOT sets mileage standards in
no way licenses EPA to shirk its environmental responsibilities.
EPA has been charged with protecting the public’s “health” and
“welfare,” 42 U. S. C. §7521(a)(1), a statutory obligation
wholly independent of DOT’s mandate to promote energy efficiency.
See Energy Policy and Conservation Act, §2(5), 89 Stat. 874, 42 U.
S. C. §6201(5). The two obligations may overlap, but there is
no reason to think the two agencies cannot both administer their
obligations and yet avoid inconsistency. While the
Congresses that drafted §202(a)(1) might not have appreciated the
possibility that burning fossil fuels could lead to global warming,
they did understand that without regulatory flexibility, changing
circumstances and scientific developments would soon render the
Clean Air Act obsolete. The broad language of §202(a)(1) reflects
an intentional effort to confer the flexibility necessary to
forestall such obsolescence. See Pennsylvania Dept. of
Corrections v. Yeskey , 524 U. S. 206 , 212
(1998) (“[T]he fact that a statute can be applied in situations not
expressly anticipated by Congress does not demonstrate ambiguity.
It demonstrates breadth” (internal quotation marks omitted)).
Because greenhouse gases fit well within the Clean Air Act’s
capacious definition of “air pollutant,” we hold that EPA has the
statutory authority to regulate the emission of such gases from new
motor vehicles. VII The alternative basis for EPA’s
decision—that even if it does have statutory authority to regulate
greenhouse gases, it would be unwise to do so at this time—rests on
reasoning divorced from the statutory text. While the statute does
condition the exercise of EPA’s authority on its formation of a
“judgment,” 42 U. S. C. §7521(a)(1), 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,” ibid. Put another way, the use of the
word “judgment” is not a roving license to ignore the statutory
text. It is but a direction to exercise discretion within defined
statutory limits. If EPA makes a finding of endangerment, the
Clean Air Act requires the agency to regulate emissions of the
deleterious pollutant from new motor vehicles. Ibid. (stating that “[EPA] shall by regulation prescribe … standards
applicable to the emission of any air pollutant from any class of
new motor vehicles”). EPA no doubt has significant latitude as to
the manner, timing, content, and coordination of its regulations
with those of other agencies. But once EPA has responded to a
petition for rulemaking, its reasons for action or inaction must
conform to the authorizing statute. Under the clear terms of the
Clean Air Act, EPA can avoid taking further action only if it
determines that greenhouse gases do not contribute to climate
change or if it provides some reasonable explanation as to why it
cannot or will not exercise its discretion to determine whether
they do. Ibid. To the extent that this constrains agency
discretion to pursue other priorities of the Administrator or the
President, this is the congressional design. EPA has
refused to comply with this clear statutory command. Instead, it
has offered a laundry list of reasons not to regulate. For example,
EPA said that a number of voluntary executive branch programs
already provide an effective response to the threat of global
warming, 68 Fed. Reg. 52932, that regulating greenhouse gases might
impair the President’s ability to negotiate with “key developing
nations” to reduce emissions, id. , at 52931, and that
curtailing motor-vehicle emissions would reflect “an inefficient,
piecemeal approach to address the climate change issue,” ibid. Although we
have neither the expertise nor the authority to evaluate these
policy judgments, it is evident they have nothing to do with
whether greenhouse gas emissions contribute to climate change.
Still less do they amount to a reasoned justification for declining
to form a scientific judgment. In particular, while the President
has broad authority in foreign affairs, that authority does not
extend to the refusal to execute domestic laws. In the Global
Climate Protection Act of 1987, Congress authorized the State
Department—not EPA—to formulate United States foreign policy with
reference to environmental matters relating to climate. See
§1103(c), 101 Stat. 1409. EPA has made no showing that it issued
the ruling in question here after consultation with the State
Department. Congress did direct EPA to consult with other agencies
in the formulation of its policies and rules, but the State
Department is absent from that list. §1103(b). Nor can EPA
avoid its statutory obligation by noting the uncertainty
surrounding various features of climate change and concluding that
it would therefore be better not to regulate at this time. See 68
Fed. Reg. 52930–52931. If the scientific uncertainty is so profound
that it precludes EPA from making a reasoned judgment as to whether
greenhouse gases contribute to global warming, EPA must say so.
That EPA would prefer not to regulate greenhouse gases because of
some residual uncertainty—which, contrary to Justice Scalia’s
apparent belief, post , at 5–8, is in fact all that it
said, see 68 Fed. Reg. 52929 (“We do not believe . . . that it
would be either effective or appropriate for EPA to establish
[greenhouse gas] standards for motor vehicles at this time”
(emphasis added))—is irrelevant. The statutory question is whether
sufficient information exists to make an endangerment
finding. In short,
EPA has offered no reasoned explanation for its refusal to decide
whether greenhouse gases cause or contribute to climate change. Its
action was therefore “arbitrary, capricious, … or otherwise not in
accordance with law.” 42 U. S. C. §7607(d)(9)(A). 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. Cf. Chevron
U. S. A. Inc. v. Natural Resources Defense Council,
Inc. , 467
U. S. 837 , 843–844 (1984). We hold only that EPA must ground
its reasons for action or inaction in the
statute. VIII The judgment of the Court of Appeals is
reversed, and the case is remanded for further proceedings
consistent with this opinion. It is so
ordered. Footnote 1 Pet. for
Cert. 22. Footnote 2 California,
Connecticut, Illinois, Maine, Massachusetts, New Jersey, New
Mexico, New York, Oregon, Rhode Island, Vermont, and
Washington. Footnote 3 District of
Columbia, American Samoa, New York City, and
Baltimore. Footnote 4 Center for
Biological Diversity, Center for Food Safety, Conservation Law
Foundation, Environmental Advocates, Environmental Defense, Friends
of the Earth, Greenpeace, International Center for Technology
Assessment, National Environmental Trust, Natural Resources Defense
Council, Sierra Club, Union of Concerned Scientists, and U. S.
Public Interest Research Group. Footnote 5 Alaska,
Idaho, Kansas, Michigan, Nebraska, North Dakota, Ohio, South
Dakota, Texas, and Utah. Footnote 6 Alliance of
Automobile Manufacturers, National Automobile Dealers Association,
Engine Manufacturers Association, Truck Manufacturers Association,
CO 2 Litigation Group, and Utility Air Regulatory
Group. Footnote 7 The 1970 version of §202(a)(1) used the phrase “which
endangers the public health or welfare” rather than the
more-protective “which may reasonably be anticipated to endanger
public health or welfare.” See §6(a) of the Clean Air Amendments of
1970, 84 Stat. 1690. Congress amended §202(a)(1) in 1977 to give
its approval to the decision in Ethyl Corp. v. EPA , 541 F. 2d 1, 25 (CADC 1976) (en banc), which held
that the Clean Air Act “and common sense … demand regulatory action
to prevent harm, even if the regulator is less than certain that
harm is otherwise inevitable.” See §401(d)(1) of the Clean Air Act
Amendments of 1977, 91 Stat. 791; see also H. R. Rep. No.
95–294, p. 49 (1977). Footnote 8 The Council on Environmental Quality had issued a report
in 1970 concluding that “[m]an may be changing his weather.”
Environmental Quality: The First Annual Report 93. Considerable
uncertainty remained in those early years, and the issue went
largely unmentioned in the congressional debate over the enactment
of the Clean Air Act. But see 116 Cong. Rec. 32914 (1970)
(statement of Sen. Boggs referring to Council’s conclusion that
“[a]ir pollution alters the climate and may produce global changes
in temperature”). Footnote 9 See Intergovernmental Panel on Climate Change, Climate
Change 2001: Synthesis Report, pp. 202–203 (2001). By drilling
through thick Antarctic ice sheets and extracting “cores,”
scientists can examine ice from long ago and extract small samples
of ancient air. That air can then be analyzed, yielding estimates
of carbon dioxide levels. Ibid . Footnote 10 A more dramatic rise was yet to come: In 2006, carbon
dioxide levels reached 382 parts per million, see Dept. of
Commerce, National Oceanic & Atmospheric Administration, Mauna
Loa CO 2 Monthly Mean Data,
www.esrl.noaa.gov/gmd/ccgg/trends/co2_mm_mlo.dat (all Internet
materials as visited Mar. 29, 2007, and available in Clerk of
Court’s case file), a level thought to exceed the concentration of
carbon dioxide in the atmosphere at any point over the past
20-million years. See Intergovernmental Panel on Climate Change,
Technical Summary of Working Group I Report 39
(2001). Footnote
11 Climate Research Board, Carbon Dioxide
and Climate: A Scientific Assessment, p. vii
(1979). Footnote
12 IPCC, Climate Change: The IPCC
Scientific Assessment, p. xi (J. Houghton, G. Jenkins, &
J. Ephraums eds. 1991). Footnote
13 The industrialized countries listed in
Annex I to the UNFCCC undertook to reduce their emissions of
greenhouse gases to 1990 levels by the year 2000. No immediate
restrictions were imposed on developing countries, including China
and India. They could choose to become Annex I countries when
sufficiently developed. Footnote
14 IPCC, Climate Change 1995, The Science
of Climate Change, p. 4. Footnote
15 Alliance for Sustainable Communities;
Applied Power Technologies, Inc.; Bio Fuels America; The California
Solar Energy Industries Assn.; Clements Environmental Corp.;
Environmental Advocates; Environmental and Energy Study Institute;
Friends of the Earth; Full Circle Energy Project, Inc.; The Green
Party of Rhode Island; Greenpeace USA; International Center for
Technology Assessment; Network for Environmental and Economic
Responsibility of the United Church of Christ; New Jersey
Environmental Watch; New Mexico Solar Energy Assn.; Oregon
Environmental Council; Public Citizen; Solar Energy Industries
Assn.; The SUN DAY Campaign. See App.
7–11. Footnote
16 See 42 U. S. C. §7607(b)(1) (“A
petition for review of action of the Administrator in promulgating
any … standard under section 7521 of this title … or final action
taken, by the Administrator under this chapter may be filed only in
the United States Court of Appeals for the District of
Columbia”). Footnote
17 The Chief Justice accuses the Court of
misreading Georgia v. Tennessee Copper Co. , 206 U. S. 230 (1907), see post , at 3–4 (dissenting opinion), and “devis[ing] a new
doctrine of state standing,” id., at 15. But no less an
authority than Hart & Wechsler’s The Federal Courts and the
Federal System understands Tennessee Copper as a standing
decision. R. Fallon, D. Meltzer, & D. Shapiro, Hart &
Wechsler’s The Federal Courts and the Federal System 290 (5th ed.
2003). Indeed, it devotes an entire section to chronicling the long
development of cases permitting States “to litigate as parens
patriae to protect quasi-sovereign interests— i.e. ,
public or governmental interests that concern the state as a
whole.” Id., at 289; see, e.g. , Missouri v. Illinois , 180 U. S. 208 , 240–241 (1901) (finding
federal jurisdiction appropriate not only “in cases involving
boundaries and jurisdiction over lands and their inhabitants, and
in cases directly affecting the property rights and interests of a
state,” but also when the “substantial impairment of the health and
prosperity of the towns and cities of the state” are at
stake). Drawing on Massachusetts v. Mellon , 262
U. S. 447 (1923), and Alfred L. Snapp & Son, Inc. v. Puerto Rico ex rel. Barez , 458 U. S. 592 (1982) (citing Missouri v. Illinois , 180 U. S. 208 (1901)), The Chief
Justice claims that we “overloo[k] the fact that our cases cast
significant doubt on a State’s standing to assert a quasi-sovereign
interest … against the Federal Government.” Post , at 5.
Not so. Mellon itself disavowed any such broad reading
when it noted that the Court had been “called upon to adjudicate,
not rights of person or property, not rights of dominion over
physical domain, [and] not quasi sovereign rights actually
invaded or threatened .” 262 U. S., at 484–485 (emphasis
added). In any event, we held in Georgia v. Pennsylvania R. Co. , 324 U. S. 439 , 447
(1945), that there is a critical difference between allowing a
State “to protect her citizens from the operation of federal
statutes” (which is what Mellon prohibits) and allowing a
State to assert its rights under federal law (which it has standing
to do). Massachusetts does not here dispute that the Clean Air Act applies to its citizens; it rather seeks to assert its
rights under the Act. See also Nebraska v. Wyoming , 515
U. S. 1 , 20 (1995) (holding that Wyoming had standing to bring
a cross-claim against the United States to vindicate its
“ ‘ quasi-sovereign ’ interests which are ‘independent
of and behind the titles of its citizens, in all the earth and air
within its domain’ ” (quoting Tennessee Copper, 206
U. S., at 237)). Footnote
18 In this regard, MacCracken’s 2004
affidavit—drafted more than a year in advance of Hurricane
Katrina—was eerily prescient. Immediately after discussing the
“particular concern” that climate change might cause an “increase
in the wind speed and peak rate of precipitation of major tropical
cyclones (i.e., hurricanes and typhoons),” MacCracken noted that
“[s]oil compaction, sea level rise and recurrent storms are
destroying approximately 20–30 square miles of Louisiana wetlands
each year. These wetlands serve as a ‘shock absorber’ for storm
surges that could inundate New Orleans, significantly enhancing the
risk to a major urban population.” ¶¶24–25, Stdg. App.
217. Footnote
19 “For example, the [Massachusetts
Department of Conservation and Recreation] owns, operates and
maintains approximately 53 coastal state parks, beaches,
reservations, and wildlife sanctuaries. [It] also owns, operates
and maintains sporting and recreational facilities in coastal
areas, including numerous pools, skating rinks, playgrounds,
playing fields, former coastal fortifications, public stages,
museums, bike trails, tennis courts, boathouses and boat ramps and
landings. Associated with these coastal properties and facilities
is a significant amount of infrastructure, which the Commonwealth
also owns, operates and maintains, including roads, parkways,
stormwater pump stations, pier[s], sea wal[l] revetments and dams.”
Hoogeboom Decl. ¶4, at 171. Footnote
20 See also id. , at 179
(declaration of Christian Jacqz) (discussing possible loss of
roughly 14 acres of land per miles of coastline by 2100); Kirshen
Decl. ¶10 , at 198 (alleging that “[w]hen such a rise in
sea level occurs, a 10-year flood will have the magnitude of the
present 100-year flood and a 100-year flood will have the magnitude
of the present 500-year flood”). Footnote
21 In dissent, The Chief Justice dismisses
petitioners’ submissions as “conclusory,” presumably because they
do not quantify Massachusetts’ land loss with the exactitude he
would prefer. Post , at 8. He therefore asserts that the
Commonwealth’s injury is “conjectur[al].” See ibid . Yet
the likelihood that Massachusetts’ coastline will recede has
nothing to do with whether petitioners have determined the precise
metes and bounds of their soon-to-be-flooded land. Petitioners
maintain that the seas are rising and will continue to rise, and
have alleged that such a rise will lead to the loss of
Massachusetts’ sovereign territory. No one, save perhaps the
dissenters, disputes those allegations. Our cases require nothing
more. Footnote
22 See UNFCCC, National Greenhouse Gas
Inventory Data for the Period 1990–2004 and Status of Reporting 14
(2006) (hereinafter Inventory Data) (reflecting emissions from
Annex I countries); UNFCCC, Sixth Compilation and Synthesis of
Initial National Communications from Parties not Included in Annex
I to the Convention 7–8 (2005) (reflecting emissions from non-Annex
I countries); see also Dept. of Energy, Energy Information Admin.,
International Energy Annual 2004, H.1co2 World Carbon Dioxide
Emissions from the Consumption and Flaring of Fossil Fuels,
1980–2004 (Table),
http://www.eia.doe.gov/pub/international/iealf/tableh1co2.xls. Footnote
23 See also Mountain States Legal
Foundation v. Glickman , 92 F. 3d 1228, 1234
(CADC 1996) (“The more drastic the injury that government action
makes more likely, the lesser the increment in probability to
establish standing”); Village of Elk Grove Village v. Evans , 997 F. 2d 328, 329 (CA7 1993) (“[E]ven a small
probability of injury is sufficient to create a case or
controversy—to take a suit out of the category of the
hypothetical—provided of course that the relief sought would, if
granted, reduce the probability”). Footnote
24 In his dissent, The Chief Justice
expresses disagreement with the Court’s holding in United
States v. Students Challenging Regulatory Agency
Procedures (SCRAP) , 412 U. S. 669 , 687–688
(1973). He does not, however, disavow this portion of Justice
Stewart’s opinion for the Court: “Unlike the specific and geographically limited federal action
of which the petitioner complained in Sierra Club [v. Morton, 405
U. S. 727 (1972)], the challenged agency action in this case is
applicable to substantially all of the Nation’s railroads, and thus
allegedly has an adverse environmental impact on all the natural
resources of the country. Rather than a limited group of persons
who used a picturesque valley in California, all persons who
utilize the scenic resources of the country, and indeed all who
breathe its air, could claim harm similar to that alleged by the
environmental groups here. But we have already made it clear that
standing is not to be denied simply because many people suffer the
same injury. Indeed some of the cases on which we relied in Sierra Club demonstrated the patent fact that persons
across the Nation could be adversely affected by major governmental
actions. To deny standing to persons who are in fact injured
simply because many others are also injured, would mean that the
most injurious and widespread Government actions could be
questioned by nobody . We cannot accept that conclusion.” Ibid. (citations omitted and emphasis
added). It is moreover quite wrong to analogize the
legal claim advanced by Massachusetts and the other public and
private entities who challenge EPA’s parsimonious construction of
the Clean Air Act to a mere “lawyer’s game.” See post , at
14. Footnote
25 See Department of Housing and Urban
Development v. Rucker , 535 U. S. 125 , 131
(2002) (observing that “ ‘any’ … has an expansive meaning,
that is, one or some indiscriminately of whatever kind” (some
internal quotation marks omitted)). Footnote
26 In dissent, Justice Scalia maintains
that because greenhouse gases permeate the world’s atmosphere
rather than a limited area near the earth’s surface, EPA’s
exclusion of greenhouse gases from the category of air pollution
“agent[s]” is entitled to deference under Chevron U. S. A.
Inc. v. Natural Resources Defense Council,
Inc. 467
U. S. 837 (1984). See post , at 11–13. EPA’s
distinction, however, finds no support in the text of the statute,
which uses the phrase “the ambient air” without distinguishing
between atmospheric layers. Moreover, it is a plainly unreasonable
reading of a sweeping statutory provision designed to capture
“ any physical, chemical … substance or matter which is
emitted into or otherwise enters the ambient air.” 42 U. S. C.
§7602(g). Justice Scalia does not (and cannot) explain why Congress
would define “air pollutant” so carefully and so broadly, yet
confer on EPA the authority to narrow that definition whenever
expedient by asserting that a particular substance is not an
“agent.” At any rate, no party to this dispute contests that
greenhouse gases both “ente[r] the ambient air” and tend to warm
the atmosphere. They are therefore unquestionably “agent[s]” of air
pollution. Footnote
27 See United States v. Price , 361
U. S. 304 , 313 (1960) (holding that “the views of a subsequent
Congress form a hazardous basis for inferring the intent of an
earlier one”); see also Cobell v. Norton , 428
F. 3d 1070, 1075 (CADC 2005) (“[P]ost-enactment legislative
history is not only oxymoronic but inherently entitled to little
weight”). Footnote
28 See, e.g. , National Climate
Program Act, §5, 92 Stat. 601, 15 U. S. C. §2901 et
seq. (calling for the establishment of a National Climate
Program and for additional climate change research); Global Climate
Protection Act of 1987, §1103, 101 Stat. 1408–1409 (directing EPA
and the Secretary of State to “jointly” develop a “coordinated
national policy on global climate change” and report to Congress);
Global Change Research Act of 1990, Tit. I, 104 Stat. 3097, 15 U.
S. C. §§2921–2938 (establishing for the “development and
coordination of a comprehensive and integrated United States
research program” to aid in “understand[ing] … human-induced and
natural processes of climate change”); Global Climate Change
Prevention Act of 1990, 104 Stat. 4058, 7 U. S. C. §6701 et seq. (directing the Dept. of Agriculture to study the
effects of climate change on forestry and agriculture); Energy
Policy Act of 1992, §§1601–1609, 106 Stat. 2999, 42 U. S. C.
§§13381–13388 (requiring the Secretary of Energy to report on
information pertaining to climate
change). Footnote
29 We are moreover puzzled by EPA’s
roundabout argument that because later Congresses chose to address
stratospheric ozone pollution in a specific legislative provision,
it somehow follows that greenhouse gases cannot be air pollutants
within the meaning of the Clean Air
Act. ROBERTS, C. J., DISSENTING MASSACHUSETTS V. EPA 549 U. S. ____ (2007) SUPREME COURT OF THE UNITED STATES NO. 05-1120 MASSACHUSETTS, et al., PETITIONERS v. ENVIRON- MENTAL PROTECTION AGENCY et al.

															on writ of certiorari to the united states court of
appeals for the district of columbia circuit

															[April 2, 2007]

															   Chief Justice Roberts, with whom
Justice Scalia, Justice Thomas, and Justice Alito join,
dissenting.

															   Global warming may be a “crisis,”
even “the most pressing environmental problem of our time.” Pet.
for Cert. 26, 22. Indeed, it may ultimately affect nearly everyone
on the planet in some potentially adverse way, and it may be that
governments have done too little to address it. It is not a
problem, however, that has escaped the attention of policymakers in
the Executive and Legislative Branches of our Government, who
continue to consider regulatory, legislative, and treaty-based
means of addressing global climate change.

															   Apparently dissatisfied with the pace of
progress on this issue in the elected branches, petitioners have
come to the courts claiming broad-ranging injury, and attempting to
tie that injury to the Government’s alleged failure to comply with
a rather narrow statutory provision. I would reject these
challenges as nonjusticiable. Such a conclusion involves no
judgment on whether global warming exists, what causes it, or the
extent of the problem. Nor does it render petitioners without
recourse. This Court’s standing jurisprudence simply recognizes
that redress of grievances of the sort at issue here “is the
function of Congress and the Chief Executive,” not the federal
courts. Lujan v. Defenders of Wildlife , 504 U. S. 555 , 576 (1992). I would
vacate the judgment below and remand for dismissal of the petitions
for review.

															I

															   Article III, §2, of the
Constitution limits the federal judicial power to the adjudication
of “Cases” and “Controversies.” “If a dispute is not a proper case
or controversy, the courts have no business deciding it, or
expounding the law in the course of doing so.” DaimlerChrysler
Corp. v. Cuno , 547 U. S. ___, ___ (2006) (slip op.,
at 5). “Standing to sue is part of the common understanding of what
it takes to make a justiciable case,” Steel Co. v. Citizens for Better Environment , 523 U. S. 83 , 102 (1998),
and has been described as “an essential and unchanging part of the
case-or-controversy requirement of Article III,” Defenders of
Wildlife , supra , at 560.

															   Our modern framework for
addressing standing is familiar: “A plaintiff must allege personal
injury fairly traceable to the defendant’s allegedly unlawful
conduct and likely to be redressed by the requested relief.” DaimlerChrysler , supra , at ___ (slip op., at 6)
(quoting Allen v. Wright , 468 U. S. 737 , 751
(1984) (internal quotation marks omitted)). Applying that standard
here, petitioners bear the burden of alleging an injury that is
fairly traceable to the Environmental Protection Agency’s failure
to promulgate new motor vehicle greenhouse gas emission standards,
and that is likely to be redressed by the prospective issuance of
such standards.

															   Before determining whether petitioners can
meet this familiar test, however, the Court changes the rules. It
asserts that “States are not normal litigants for the purposes of
invoking federal jurisdiction,” and that given “Massachusetts’
stake in protecting its quasi-sovereign interests, the Commonwealth
is entitled to special solicitude in our standing
analysis.” Ante , at 15, 17 (emphasis added).

															   Relaxing Article III standing requirements
because asserted injuries are pressed by a State, however, has no
basis in our jurisprudence, and support for any such “special
solicitude” is conspicuously absent from the Court’s opinion. The
general judicial review provision cited by the Court, 42 U.
S. C. §7607(b)(1), affords States no special rights or status.
The Court states that “Congress has ordered EPA to protect
Massachusetts (among others)” through the statutory provision at
issue, §7521(a)(1), and that “Congress has . . . recognized a
concomitant procedural right to challenge the rejection of its
rulemaking petition as arbitrary and capricious.” Ante , at
16. The reader might think from this unfortunate phrasing that
Congress said something about the rights of States in this
particular provision of the statute. Congress knows how to do that
when it wants to, see, e.g., §7426(b) (affording States
the right to petition EPA to directly regulate certain sources of
pollution), but it has done nothing of the sort here. Under the law
on which petitioners rely, Congress treated public and private
litigants exactly the same.

															   Nor does the case law cited by the Court
provide any support for the notion that Article III somehow
implicitly treats public and private litigants differently. The
Court has to go back a full century in an attempt to justify its
novel standing rule, but even there it comes up short. The Court’s
analysis hinges on Georgia v. Tennessee Copper
Co. , 206 U. S.
230 (1907)—a case that did indeed draw a distinction between a
State and private litigants, but solely with respect to available
remedies. The case had nothing to do with Article III standing.

															   In Tennessee Copper , the State of
Georgia sought to enjoin copper companies in neighboring Tennessee
from discharging pollutants that were inflicting “a wholesale
destruction of forests, orchards and crops” in bordering Georgia
counties. Id. , at 236. Although the State owned very
little of the territory allegedly affected, the Court reasoned that
Georgia—in its capacity as a “ quasi -sovereign”—“has an
interest independent of and behind the titles of its citizens, in
all the earth and air within its domain.” Id. , at 237. The
Court explained that while “[t]he very elements that would be
relied upon in a suit between fellow-citizens as a ground for
equitable relief [were] wanting,” a State “is not lightly to be
required to give up quasi -sovereign rights for pay.” Ibid. Thus while a complaining private litigant would have
to make do with a legal remedy—one “for pay”—the State was
entitled to equitable relief. See id. , at
237–238.

															   In contrast to the present case, there was no
question in Tennessee Copper about Article III injury. See id. , at 238–239. There was certainly no suggestion that
the State could show standing where the private parties could not;
there was no dispute, after all, that the private landowners had
“an action at law.” Id. , at 238. Tennessee Copper has since stood for nothing more than a State’s right, in an
original jurisdiction action, to sue in a representative capacity
as parens patriae . See, e.g., Maryland v. Louisiana , 451 U. S. 725 , 737
(1981). Nothing about a State’s ability to sue in that capacity
dilutes the bedrock requirement of showing injury, causation, and
redressability to satisfy Article III.

															   A claim of parens patriae standing is
distinct from an allegation of direct injury. See Wyoming v. Oklahoma , 502 U. S. 437 , 448–449,
451 (1992). Far from being a substitute for Article III injury, parens patriae actions raise an additional hurdle for a
state litigant: the articulation of a “quasi-sovereign interest”
“ apart from the interests of particular private parties.” Alfred L. Snapp & Son, Inc. v. Puerto Rico ex rel.
Barez , 458 U. S. 592 , 607 (1982) (emphasis
added) (cited ante , at 16). Just as an association suing
on behalf of its members must show not only that it represents the
members but that at least one satisfies Article III requirements,
so too a State asserting quasi-sovereign interests as parens
patriae must still show that its citizens satisfy Article III.
Focusing on Massachusetts’s interests as quasi-sovereign makes the
required showing here harder, not easier. The Court, in effect,
takes what has always been regarded as a necessary condition for parens patriae standing—a quasi-sovereign
interest—and converts it into a sufficient showing for
purposes of Article III.

															   What is more, the Court’s reasoning falters on
its own terms. The Court asserts that Massachusetts is entitled to
“special solicitude” due to its “quasi-sovereign interests,” ante , at 17, but then applies our Article III standing
test to the asserted injury of the State’s loss of coastal
property. See ante , at 19 (concluding that Massachusetts
“has alleged a particularized injury in its capacity as a
landowner ” (emphasis added)). In the context of parens
patriae standing, however, we have characterized state
ownership of land as a “nonsovereign interes[t]” because a State
“is likely to have the same interests as other similarly situated
proprietors.” Alfred L. Snapp & Son , supra ,
at 601.

															   On top of everything else, the Court overlooks
the fact that our cases cast significant doubt on a State’s
standing to assert a quasi-sovereign interest—as opposed to a
direct injury—against the Federal Government. As a general rule, we
have held that while a State might assert a quasi-sovereign right
as parens patriae “for the protection of its citizens, it
is no part of its duty or power to enforce their rights in respect
of their relations with the Federal Government. In that field it is
the United States, and not the State, which represents them.” Massachusetts v. Mellon , 262 U. S. 447 , 485–486
(1923) (citation omitted); see also Alfred L. Snapp &
Son , supra , at 610, n. 16.

															   All of this presumably explains why
petitioners never cited Tennessee Copper in their briefs
before this Court or the D. C. Circuit. It presumably explains
why not one of the legion of amici supporting petitioners
ever cited the case. And it presumably explains why not one of the
three judges writing below ever cited the case either. Given that
one purpose of the standing requirement is “ ‘to assure that
concrete adverseness which sharpens the presentation of issues upon
which the court so largely depends for illumination,’ ” ante , at 13–14 (quoting Baker v. Carr , 369 U. S. 186 ,
204 (1962)), it is ironic that the Court today adopts a new theory
of Article III standing for States without the benefit of briefing
or argument on the point.[ Footnote
1 ]

															II

															   It is not at all clear how the
Court’s “special solicitude” for Massachusetts plays out in the
standing analysis, except as an implicit concession that
petitioners cannot establish standing on traditional terms. But the
status of Massachusetts as a State cannot compensate for
petitioners’ failure to demonstrate injury in fact, causation, and
redressability.

															   When the Court actually applies
the three-part test, it focuses, as did the dissent below, see 415
F. 3d 50, 64 (CADC 2005) (opinion of Tatel, J.), on the State’s
asserted loss of coastal land as the injury in fact. If petitioners
rely on loss of land as the Article III injury, however, they must
ground the rest of the standing analysis in that specific injury.
That alleged injury must be “concrete and particularized,” Defenders of Wildlife , 504 U. S., at 560, and “distinct
and palpable,” Allen , 468 U. S., at 751 (internal
quotation marks omitted). Central to this concept of
“particularized” injury is the requirement that a plaintiff be
affected in a “personal and individual way,” Defenders of
Wildlife , 504 U. S., at 560, n. 1, and seek relief that
“directly and tangibly benefits him” in a manner distinct from its
impact on “the public at large,” id. , at 573–574. Without
“particularized injury, there can be no confidence of ‘a real need
to exercise the power of judicial review’ or that relief can be
framed ‘no broader than required by the precise facts to which the
court’s ruling would be applied.’ ” Warth v. Seldin , 422
U. S. 490 , 508 (1975) (quoting Schlesinger v. Reservists Comm. to Stop the War , 418 U. S. 208 , 221–222
(1974)).

															   The very concept of global warming seems
inconsistent with this particularization requirement. Global
warming is a phenomenon “harmful to humanity at large,” 415
F. 3d, at 60 (Sentelle, J., dissenting in part and concurring
in judgment), and the redress petitioners seek is focused no more
on them than on the public generally—it is literally to change the
atmosphere around the world.

															   If petitioners’ particularized injury is loss
of coastal land, it is also that injury that must be “actual or
imminent, not conjectural or hypothetical,” Defenders of
Wildlife, supra , at 560 (internal quotation marks omitted),
“real and immediate,” Los Angeles v. Lyons , 461 U. S. 95 , 102
(1983) (internal quotation marks omitted), and “certainly
impending,” Whitmore v. Arkansas , 495 U. S. 149 , 158 (1990) (internal
quotation marks omitted).

															   As to “actual” injury, the Court observes that
“global sea levels rose somewhere between 10 and 20 centimeters
over the 20th century as a result of global warming” and that
“[t]hese rising seas have already begun to swallow Massachusetts’
coastal land.” Ante , at 19. But none of petitioners’
declarations supports that connection. One declaration states that
“a rise in sea level due to climate change is occurring on the
coast of Massachusetts, in the metropolitan Boston area,” but there
is no elaboration. Petitioners’ Standing Appendix in No. 03–1361,
etc. (CADC), p. 196 (Stdg. App.). And the declarant goes on to
identify a “significan[t]” non -global-warming cause of
Boston’s rising sea level: land subsidence. Id. , at 197;
see also id. , at 216. Thus, aside from a single conclusory
statement, there is nothing in petitioners’ 43 standing
declarations and accompanying exhibits to support an inference of
actual loss of Massachusetts coastal land from 20th century global
sea level increases. It is pure conjecture.

															   The Court’s attempts to identify “imminent” or
“certainly impending” loss of Massachusetts coastal land fares no
better. See ante , at 19–20. One of petitioners’ declarants
predicts global warming will cause sea level to rise by 20 to 70
centimeters by the year 2100 . Stdg. App. 216. Another uses
a computer modeling program to map the Commonwealth’s coastal land
and its current elevation, and calculates that the high-end
estimate of sea level rise would result in the loss of significant
state-owned coastal land. Id. , at 179. But the computer
modeling program has a conceded average error of about 30
centimeters and a maximum observed error of 70 centimeters. Id. , at 177–178. As an initial matter, if it is possible
that the model underrepresents the elevation of coastal land to an
extent equal to or in excess of the projected sea level rise, it is
difficult to put much stock in the predicted loss of land. But even
placing that problem to the side, accepting a century-long time
horizon and a series of compounded estimates renders requirements
of imminence and immediacy utterly toothless. See Defenders of
Wildlife , supra , at 565, n. 2 (while the concept
of “ ‘imminence’ ” in standing doctrine is “somewhat
elastic,” it can be “stretched beyond the breaking point”).
“Allegations of possible future injury do not satisfy the
requirements of Art. III. A threatened injury must be certainly
impending to constitute injury in fact.” Whitmore , supra , at 158. (internal quotation marks omitted; emphasis
added).

															III

															   Petitioners’ reliance on
Massachusetts’s loss of coastal land as their injury in fact for
standing purposes creates insurmountable problems for them with
respect to causation and redressability. To establish standing,
petitioners must show a causal connection between that specific
injury and the lack of new motor vehicle greenhouse gas emission
standards, and that the promulgation of such standards would likely
redress that injury. As is often the case, the questions of
causation and redressability overlap. See Allen , 468 U.
S., at 753, n. 19 (observing that the two requirements were
“initially articulated by this Court as two facets of a single
causation requirement” (internal quotation marks omitted)). And
importantly, when a party is challenging the Government’s allegedly
unlawful regulation, or lack of regulation, of a third party,
satisfying the causation and redressability requirements becomes
“substantially more difficult.” Defenders of Wildlife , supra , at 562 (internal quotation marks omitted); see also Warth , supra , at 504–505.

															   Petitioners view the relationship
between their injuries and EPA’s failure to promulgate new motor
vehicle greenhouse gas emission standards as simple and direct:
Domestic motor vehicles emit carbon dioxide and other greenhouse
gases. Worldwide emissions of greenhouse gases contribute to global
warming and therefore also to petitioners’ alleged injuries.
Without the new vehicle standards, greenhouse gas emissions—and
therefore global warming and its attendant harms—have been higher
than they otherwise would have been; once EPA changes course, the
trend will be reversed.

															   The Court ignores the complexities of global
warming, and does so by now disregarding the “particularized”
injury it relied on in step one, and using the dire nature of
global warming itself as a bootstrap for finding causation and
redressability. First, it is important to recognize the extent of
the emissions at issue here. Because local greenhouse gas emissions
disperse throughout the atmosphere and remain there for anywhere
from 50 to 200 years, it is global emissions data that are
relevant. See App. to Pet. for Cert. A–73. According to one of
petitioners’ declarations, domestic motor vehicles contribute about
6 percent of global carbon dioxide emissions and 4 percent of
global greenhouse gas emissions. Stdg. App. 232. The amount of
global emissions at issue here is smaller still; §202(a)(1) of the
Clean Air Act covers only new motor vehicles and new motor vehicle engines, so petitioners’ desired
emission standards might reduce only a fraction of 4 percent of
global emissions.

															   This gets us only to the relevant greenhouse
gas emissions; linking them to global warming and ultimately to
petitioners’ alleged injuries next requires consideration of
further complexities. As EPA explained in its denial of
petitioners’ request for rulemaking,

															“predicting future climate change necessarily
involves a complex web of economic and physical factors including:
our ability to predict future global anthropogenic emissions of
[greenhouse gases] and aerosols; the fate of these emissions once
they enter the atmosphere (e.g., what percentage are absorbed by
vegetation or are taken up by the oceans); the impact of those
emissions that remain in the atmosphere on the radiative properties
of the atmosphere; changes in critically important climate
feedbacks (e.g., changes in cloud cover and ocean circulation);
changes in temperature characteristics (e.g., average temperatures,
shifts in daytime and evening temperatures); changes in other
climatic parameters (e.g., shifts in precipitation, storms); and
ultimately the impact of such changes on human health and welfare
(e.g., increases or decreases in agricultural productivity, human
health impacts).” App. to Pet. for Cert. A–83 through A–84.

															   Petitioners are never able to
trace their alleged injuries back through this complex web to the
fractional amount of global emissions that might have been limited
with EPA standards. In light of the bit-part domestic new motor
vehicle greenhouse gas emissions have played in what petitioners
describe as a 150-year global phenomenon, and the myriad additional
factors bearing on petitioners’ alleged injury—the loss of
Massachusetts coastal land—the connection is far too speculative to
establish causation.

															IV

															   Redressability is even more
problematic. To the tenuous link between petitioners’ alleged
injury and the indeterminate fractional domestic emissions at issue
here, add the fact that petitioners cannot meaningfully predict
what will come of the 80 percent of global greenhouse gas emissions
that originate outside the United States. As the Court
acknowledges, “developing countries such as China and India are
poised to increase greenhouse gas emissions substantially over the
next century,” ante, at 23, so the domestic emissions at
issue here may become an increasingly marginal portion of global
emissions, and any decreases produced by petitioners’ desired
standards are likely to be overwhelmed many times over by emissions
increases elsewhere in the world.

															   Petitioners offer declarations
attempting to address this uncertainty, contending that “[i]f the
U. S. takes steps to reduce motor vehicle emissions, other
countries are very likely to take similar actions regarding their
own motor vehicles using technology developed in response to the U.
S. program.” Stdg. App. 220; see also id. , at 311–312. In
other words, do not worry that other countries will contribute far
more to global warming than will U. S. automobile emissions;
someone is bound to invent something, and places like the People’s
Republic of China or India will surely require use of the new
technology, regardless of cost. The Court previously has explained
that when the existence of an element of standing “depends on the
unfettered choices made by independent actors not before the courts
and whose exercise of broad and legitimate discretion the courts
cannot presume either to control or to predict,” a party must
present facts supporting an assertion that the actor will proceed
in such a manner. Defenders of Wildlife , 504 U. S., at 562
(quoting ASARCO Inc. v. Kadish , 490 U. S. 605 , 615
(1989) (opinion of Kennedy, J.); internal quotation marks omitted).
The declarations’ conclusory (not to say fanciful) statements do
not even come close.

															   No matter, the Court reasons, because any decrease in domestic emissions will “slow the pace of
global emissions increases, no matter what happens elsewhere.” Ante , at 23. Every little bit helps, so Massachusetts can
sue over any little bit.

															   The Court’s sleight-of-hand is in failing to
link up the different elements of the three-part standing test.
What must be likely to be redressed is the particular
injury in fact. The injury the Court looks to is the asserted loss
of land. The Court contends that regulating domestic motor vehicle
emissions will reduce carbon dioxide in the atmosphere, and
therefore redress Massachusetts’s injury. But even if
regulation does reduce emissions—to some indeterminate
degree, given events elsewhere in the world—the Court never
explains why that makes it likely that the injury in
fact—the loss of land—will be redressed. Schoolchildren know that a
kingdom might be lost “all for the want of a horseshoe nail,” but
“likely” redressability is a different matter. The realities make
it pure conjecture to suppose that EPA regulation of new automobile
emissions will likely prevent the loss of Massachusetts
coastal land.

															V

															   Petitioners’ difficulty in
demonstrating causation and redressability is not surprising given
the evident mismatch between the source of their alleged
injury—catastrophic global warming—and the narrow subject matter of
the Clean Air Act provision at issue in this suit. The mismatch
suggests that petitioners’ true goal for this litigation may be
more symbolic than anything else. The constitutional role of the
courts, however, is to decide concrete cases—not to serve as a
convenient forum for policy debates. See Valley Forge Christian
College v. Americans United for Separation of Church and
State, Inc. , 454 U. S. 464 , 472
(1982) (“[Standing] tends to assure that the legal questions
presented to the court will be resolved, not in the rarified
atmosphere of a debating society, but in a concrete factual context
conducive to a realistic appreciation of the consequences of
judicial action”).

															   When dealing with legal doctrine
phrased in terms of what is “fairly” traceable or “likely” to be
redressed, it is perhaps not surprising that the matter is subject
to some debate. But in considering how loosely or rigorously to
define those adverbs, it is vital to keep in mind the purpose of
the inquiry. The limitation of the judicial power to cases and
controversies “is crucial in maintaining the tripartite allocation
of power set forth in the Constitution.” DaimlerChrysler ,
547 U. S., at ___ (slip op., at 5) (internal quotation marks
omitted). In my view, the Court today—addressing Article III’s
“core component of standing,” Defenders of Wildlife , supra , at 560—fails to take this limitation seriously.

															   To be fair, it is not the first time the Court
has done so. Today’s decision recalls the previous high-water mark
of diluted standing requirements, United States v. Students Challenging Regulatory Agency Procedures (SCRAP) , 412 U. S. 669 (1973). SCRAP involved “[p]robably the most attenuated
injury conferring Art. III standing” and “surely went to the very
outer limit of the law”—until today. Whitmore , 495 U. S.,
at 158–159; see also Lujan v. National Wildlife
Federation , 497
U. S. 871 , 889 (1990) ( SCRAP “has never since been
emulated by this Court”). In SCRAP , the Court based an
environmental group’s standing to challenge a railroad freight rate
surcharge on the group’s allegation that increases in railroad
rates would cause an increase in the use of nonrecyclable goods,
resulting in the increased need for natural resources to produce
such goods. According to the group, some of these resources might
be taken from the Washington area, resulting in increased refuse
that might find its way into area parks, harming the group’s
members. 412 U. S., at 688.

															   Over time, SCRAP became emblematic
not of the looseness of Article III standing requirements, but of
how utterly manipulable they are if not taken seriously as a matter
of judicial self-restraint. SCRAP made standing seem a
lawyer’s game, rather than a fundamental limitation ensuring that
courts function as courts and not intrude on the politically
accountable branches. Today’s decision is SCRAP for a new
generation.[ Footnote 2 ]

															   Perhaps the Court recognizes as much. How else
to explain its need to devise a new doctrine of state standing to
support its result? The good news is that the Court’s “special
solicitude” for Massachusetts limits the future applicability of
the diluted standing requirements applied in this case. The bad
news is that the Court’s self-professed relaxation of those Article
III requirements has caused us to transgress “the proper—and
properly limited—role of the courts in a democratic society.” Allen , 468 U. S., at 750 (internal quotation marks
omitted).

															   I respectfully dissent. Footnote 1 The Court seems to think we do not recognize
that Tennessee Copper is a case about parens
patriae standing, ante , at 17, n. 17, but we
have no doubt about that. The point is that nothing in our cases
(or Hart & Wechsler) suggests that the prudential requirements
for parens patriae standing, see Republic of
Venezuela v. Philip Morris Inc. , 287 F. 3d 192,
199, n. (CADC 2002) (observing that “ parens patriae is
merely a species of prudential standing” (internal quotation marks
omitted)), can somehow substitute for, or alter the content of, the
“irreducible constitutional minimum” requirements of injury in
fact, causation, and redressability under Article III. Lujan v. Defenders of Wildlife , 504 U. S. 555 , 560 (1992). Georgia v. Pennsylvania R.
Co. , 324 U. S.
439 (1945), is not to the contrary. As the caption makes clear
enough, the fact that a State may assert rights under a federal
statute as parens patriae in no way refutes our clear
ruling that “[a] State does not have standing as parens
patriae to bring an action against the Federal Government.” Alfred L. Snapp & Son, Inc. v. Puerto Rico ex rel.
Barez , 458 U. S. 592 , 610, n. 16
(1982). Footnote 2 The difficulty with SCRAP , and the
reason it has not been followed, is not the portion cited by the
Court. See ante , at 23–24, n. 24. Rather, it is the attenuated nature of the injury there, and here, that is
so troubling. Even in SCRAP , the Court noted that what was
required was “something more than an ingenious academic exercise in
the conceivable,” 412 U. S., at 688, and we have since understood
the allegation there to have been “that the string of occurrences
alleged would happen immediately ,” Whitmore v. Arkansas , 495 U. S. 149 , 159 (1990) (emphasis
added). That is hardly the case here.

															   The Court says it is “quite wrong” to compare
petitioners’ challenging “EPA’s parsimonious construction of the
Clean Air Act to a mere ‘lawyer’s game.’ ” Ante , at
24, n. 24. Of course it is not the legal challenge that is merely
“an ingenious academic exercise in the conceivable,” SCRAP , supra , at 688, but the assertions made in
support of standing. SCALIA, J., DISSENTING MASSACHUSETTS V. EPA 549 U. S. ____ (2007) SUPREME COURT OF THE UNITED STATES NO. 05-1120 MASSACHUSETTS, et al., PETITIONERS v. ENVIRON- MENTAL PROTECTION AGENCY et al.

															on writ of certiorari to the united states court of
appeals for the district of columbia circuit

															[April 2, 2007]

															   Justice Scalia, with whom The
Chief Justice, Justice Thomas, and Justice Alito join,
dissenting.

															   I join The Chief Justice’s
opinion in full, and would hold that this Court has no jurisdiction
to decide this case because petitioners lack standing. The Court
having decided otherwise, it is appropriate for me to note my
dissent on the merits.

															I

															A

															   The provision of law at the heart
of this case is §202(a)(1) of the Clean Air Act (CAA), which
provides that the Administrator of the Environmental Protection
Agency (EPA) “shall by regulation prescribe … standards applicable
to the emission of any air pollutant from any class or classes of
new motor vehicles or new motor vehicle engines, which in his
judgment cause, or contribute to, air pollution which may
reasonably be anticipated to endanger public health or welfare.” 42
U. S. C. §7521(a)(1) (emphasis added). As the Court
recognizes, the statute “condition[s] the exercise of EPA’s
authority on its formation of a ‘judgment.’ ” Ante ,
at 30. There is no dispute that the Administrator has made no such
judgment in this case. See ante, at 32 (“We need not and
do not reach the question whether on remand EPA must make an
endangerment finding”); 68 Fed. 52929 (2003) (“[N]o Administrator
has made a finding under any of the CAA’s regulatory provisions
that CO 2 meets the applicable statutory criteria
for regulation”). The question
thus arises: Does anything require the Administrator to
make a “judgment” whenever a petition for rulemaking is filed?
Without citation of the statute or any other authority, the Court
says yes. Why is that so? When Congress wishes to make private
action force an agency’s hand, it knows how to do so. See, e.g., Brock v. Pierce County , 476 U. S. 253 , 254–255
(1986) (discussing the Comprehensive Employment and Training Act
(CETA), 92 Stat. 1926, 29 U. S. C. §816(b) (1976 ed., Supp.
V), which “provide[d] that the Secretary of Labor ‘shall’ issue a
final determination as to the misuse of CETA funds by a grant
recipient within 120 days after receiving a complaint alleging such
misuse”). Where does the CAA say that the EPA Administrator is
required to come to a decision on this question whenever a
rulemaking petition is filed? The Court points to no such provision
because none exists. Instead, the Court invents a
multiple-choice question that the EPA Administrator must answer
when a petition for rulemaking is filed. The Administrator must
exercise his judgment in one of three ways: (a) by concluding that
the pollutant does cause, or contribute to, air pollution
that endangers public welfare (in which case EPA is required to
regulate); (b) by concluding that the pollutant does not cause, or contribute to, air pollution that endangers public
welfare (in which case EPA is not required to regulate);
or (c) by “provid[ing] some reasonable explanation as to why it
cannot or will not exercise its discretion to determine whether”
greenhouse gases endanger public welfare, ante , at 30, (in
which case EPA is not required to regulate). I am willing to assume, for
the sake of argument, that the Administrator’s discretion in this
regard is not entirely unbounded—that if he has no reasonable basis
for deferring judgment he must grasp the nettle at once. The Court,
however, with no basis in text or precedent, rejects all of EPA’s
stated “policy judgments” as not “amount[ing] to a reasoned
justification,” ante , at 31, effectively narrowing the
universe of potential reasonable bases to a single one: Judgment
can be delayed only if the Administrator concludes that
“the scientific uncertainty is [too] profound.” Ibid . The
Administrator is precluded from concluding for other
reasons “that it would … be better not to regulate at this
time.” Ibid.[ Footnote
1 ] Such other reasons—perfectly valid reasons—were set
forth in the agency’s statement. “We do not believe … that it would
be either effective or appropriate for EPA to establish [greenhouse
gas] standards for motor vehicles at this time. As described in
detail below, the President has laid out a comprehensive approach
to climate change that calls for near-term voluntary actions and
incentives along with programs aimed at reducing scientific
uncertainties and encouraging technological development so that the
government may effectively and efficiently address the climate
change issue over the long term. .     .     .     .     . “[E]stablishing [greenhouse
gas] emission standards for U. S. motor vehicles at this time would
… result in an inefficient, piecemeal approach to addressing the
climate change issue. The U. S. motor vehicle fleet is one of many
sources of [greenhouse gas] emissions both here and abroad, and
different [greenhouse gas] emission sources face different
technological and financial challenges in reducing emissions. A
sensible regulatory scheme would require that all significant
sources and sinks of [greenhouse gas] emissions be considered in
deciding how best to achieve any needed emission
reductions. “Unilateral EPA regulation of
motor vehicle [greenhouse gas] emissions could also weaken U. S.
efforts to persuade developing countries to reduce the [greenhouse
gas] intensity of their economies. Considering the large
populations and growing economies of some developing countries,
increases in their [greenhouse gas] emissions could quickly
overwhelm the effects of [greenhouse gas] reduction measures in
developed countries. Any potential benefit of EPA regulation could
be lost to the extent other nations decided to let their emissions
significantly increase in view of U. S. emissions reductions.
Unavoidably, climate change raises important foreign policy issues,
and it is the President’s prerogative to address them.” 68 Fed.
Reg. 52929–52931 (footnote omitted). The Court
dismisses this analysis as “rest[ing] on reasoning divorced from
the statutory text.” Ante, at 30. “While the statute does
condition the exercise of EPA’s authority on its formation of a
‘judgment,’ … 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.’ ” Ibid . True but irrelevant. When the Administrator makes a judgment whether to regulate greenhouse gases,
that judgment must relate to whether they are air pollutants that
“cause, or contribute to, air pollution which may reasonably be
anticipated to endanger public health or welfare.” 42 U. S. C.
§7521(a)(1). But the statute says nothing at all about the
reasons for which the Administrator may defer making a
judgment—the permissible reasons for deciding not to grapple with
the issue at the present time. Thus, the various “policy”
rationales, ante, at 31, that the Court criticizes are not
“divorced from the statutory text,” ante, at 30, except in
the sense that the statutory text is silent, as texts are often
silent about permissible reasons for the exercise of agency
discretion. The reasons the EPA gave are surely considerations
executive agencies regularly take into account (and ought to take into account) when deciding whether to
consider entering a new field: the impact such entry would have on
other Executive Branch programs and on foreign policy. There is no
basis in law for the Court’s imposed limitation. EPA’s interpretation of the
discretion conferred by the statutory reference to “its judgment”
is not only reasonable, it is the most natural reading of the text.
The Court nowhere explains why this interpretation is incorrect,
let alone why it is not entitled to deference under Chevron U.
S. A. Inc. v. Natural Resources Defense Council,
Inc. , 467 U. S.
837 (1984). As the Administrator acted within the law in
declining to make a “judgment” for the policy reasons above set
forth, I would uphold the decision to deny the rulemaking petition
on that ground alone. B Even on the
Court’s own terms, however, the same conclusion follows. As
mentioned above, the Court gives EPA the option of determining that
the science is too uncertain to allow it to form a “judgment” as to
whether greenhouse gases endanger public welfare. Attached to this
option (on what basis is unclear) is an essay requirement: “If,”
the Court says, “the scientific uncertainty is so profound that it
precludes EPA from making a reasoned judgment as to whether
greenhouse gases contribute to global warming, EPA must say so.” Ante , at 31 . But EPA has said precisely
that—and at great length, based on information contained in a 2001
report by the National Research Council (NRC) entitled Climate
Change Science: An Analysis of Some Key Questions: “As the NRC
noted in its report, concentrations of [greenhouse gases (GHGs)]
are increasing in the atmosphere as a result of human activities
(pp. 9–12). It also noted that ‘[a] diverse array of evidence
points to a warming of global surface air temperatures’ (p. 16).
The report goes on to state, however, that ‘[b]ecause of the large
and still uncertain level of natural variability inherent in the
climate record and the uncertainties in the time histories of the
various forcing agents (and particularly aerosols), a [causal]
linkage between the buildup of greenhouse gases in the atmosphere
and the observed climate changes during the 20th century cannot be
unequivocally established. The fact that the magnitude of the
observed warming is large in comparison to natural variability as
simulated in climate models is suggestive of such a linkage, but it
does not constitute proof of one because the model simulations
could be deficient in natural variability on the decadal to century
time scale’ (p. 17). “The NRC also observed that
‘there is considerable uncertainty in current understanding of how
the climate system varies naturally and reacts to emissions of
[GHGs] and aerosols’ (p. 1). As a result of that uncertainty, the
NRC cautioned that ‘current estimate of the magnitude of future
warming should be regarded as tentative and subject to future
adjustments (either upward or downward).’ Id. It further
advised that ‘[r]educing the wide range of uncertainty inherent in
current model predictions of global climate change will require
major advances in understanding and modeling of both (1) the
factors that determine atmospheric concentrations of [GHGs] and
aerosols and (2) the so-called “feedbacks” that determine the
sensitivity of the climate system to a prescribed increase in
[GHGs].’ Id. “The science of climate
change is extraordinarily complex and still evolving. Although
there have been substantial advances in climate change science,
there continue to be important uncertainties in our understanding
of the factors that may affect future climate change and how it
should be addressed. As the NRC explained, predicting future
climate change necessarily involves a complex web of economic and
physical factors including: Our ability to predict future global
anthropogenic emissions of GHGs and aerosols; the fate of these
emissions once they enter the atmosphere ( e.g., what
percentage are absorbed by vegetation or are taken up by the
oceans); the impact of those emissions that remain in the
atmosphere on the radiative properties of the atmosphere; changes
in critically important climate feedbacks ( e.g., changes
in cloud cover and ocean circulation); changes in temperature
characteristics ( e.g., average temperatures, shifts in
daytime and evening temperatures); changes in other climatic
parameters ( e.g., shifts in precipitation, storms); and
ultimately the impact of such changes on human health and welfare
( e.g., increases or decreases in agricultural
productivity, human health impacts). The NRC noted, in particular,
that ‘[t]he understanding of the relationships between
weather/climate and human health is in its infancy and therefore
the health consequences of climate change are poorly understood’
(p. 20). Substantial scientific uncertainties limit our ability to
assess each of these factors and to separate out those changes
resulting from natural variability from those that are directly the
result of increases in anthropogenic GHGs. “Reducing the wide range of
uncertainty inherent in current model predictions will require
major advances in understanding and modeling of the factors that
determine atmospheric concentrations of greenhouse gases and
aerosols, and the processes that determine the sensitivity of the
climate system.” 68 Fed. Reg. 52930. I simply cannot conceive of what
else the Court would like EPA to say. II A Even before
reaching its discussion of the word “judgment,” the Court makes
another significant error when it concludes that “§202(a)(1) of the
Clean Air Act authorizes EPA to regulate greenhouse gas
emissions from new motor vehicles in the event that it forms a
‘judgment’ that such emissions contribute to climate change.” Ante , at 25 (emphasis added). For such authorization, the
Court relies on what it calls “the Clean Air Act’s capacious
definition of ‘air pollutant.’ ” Ante, at
30. “Air pollutant”
is defined by the Act as “any air pollution agent or combination of
such agents, including any physical, chemical, … substance or
matter which is emitted into or otherwise enters the ambient air.”
42 U. S. C. §7602(g). The Court is correct that “[c]arbon
dioxide, methane, nitrous oxide, and hydrofluorocarbons,” ante , at 26, fit within the second half of that
definition: They are “physical, chemical, … substance[s] or matter
which [are] emitted into or otherwise ente[r] the ambient air.” But
the Court mistakenly believes this to be the end of the analysis.
In order to be an “air pollutant” under the Act’s definition, the
“substance or matter [being] emitted into … the ambient air” must
also meet the first half of the definition—namely, it must
be an “air pollution agent or combination of such agents.” The
Court simply pretends this half of the definition does not
exist. The Court’s analysis
faithfully follows the argument advanced by petitioners, which
focuses on the word “including” in the statutory definition of “air
pollutant.” See Brief for Petitioners 13–14. As that argument goes,
anything that follows the word “including” must
necessarily be a subset of whatever precedes it. Thus, if
greenhouse gases qualify under the phrase following the word
“including,” they must qualify under the phrase preceding it. Since
greenhouse gases come within the capacious phrase “any physical,
chemical, … substance or matter which is emitted into or otherwise
enters the ambient air,” they must also be “air pollution agent[s]
or combination[s] of such agents,” and therefore meet the
definition of “air pollutant[s].” That is certainly one
possible interpretation of the statutory definition. The word
“including” can indeed indicate that what follows will be an
“illustrative” sampling of the general category that precedes the
word. Federal Land Bank of St. Paul v. Bismarck Lumber
Co. , 314 U. S.
95 , 100 (1941). Often, however, the examples standing alone are
broader than the general category, and must be viewed as limited in
light of that category. The Government provides a helpful (and
unanswered) example: “The phrase ‘any American automobile,
including any truck or minivan,’ would not naturally be construed
to encompass a foreign-manufactured [truck or] minivan.” Brief for
Federal Respondent 34. The general principle enunciated—that the
speaker is talking about American automobiles—carries
forward to the illustrative examples (trucks and minivans), and
limits them accordingly, even though in isolation they are broader.
Congress often uses the word “including” in this manner. In 28 U.
S. C. §1782(a), for example, it refers to “a proceeding in a
foreign or international tribunal, including criminal
investigations conducted before formal accusation.” Certainly this
provision would not encompass criminal investigations underway in a domestic tribunal. See also, e.g. , 2 U.
S. C. §54(a) (“The Clerk of the House of Representatives
shall, at the request of a Member of the House of Representatives,
furnish to the Member, for official use only, one set of a
privately published annotated version of the United States Code,
including supplements and pocket parts”); 22 U. S. C.
§2304(b)(1) (“the relevant findings of appropriate international
organizations, including nongovernmental
organizations”). In short, the word
“including” does not require the Court’s (or the petitioners’)
result. It is perfectly reasonable to view the definition of “air
pollutant” in its entirety: An air pollutant can be “any
physical, chemical, … substance or matter which is emitted into or
otherwise enters the ambient air,” but only if it retains the
general characteristic of being an “air pollution agent or
combination of such agents.” This is precisely the conclusion EPA
reached: “[A] substance does not meet the CAA definition of ‘air
pollutant’ simply because it is a ‘physical, chemical, … substance
or matter which is emitted into or otherwise enters the ambient
air.’ It must also be an ‘air pollution agent.’ ” 68 Fed. Reg.
52929, n. 3. See also id., at 52928 (“The root of the
definition indicates that for a substance to be an ‘air pollutant,’
it must be an ‘agent’ of ‘air pollution’ ”). Once again, in
the face of textual ambiguity, the Court’s application of Chevron deference to EPA’s interpretation of the word
“including” is nowhere to be found.[ Footnote 2 ] Evidently, the Court defers only to those
reasonable interpretations that it favors. B Using (as we
ought to) EPA’s interpretation of the definition of “air
pollutant,” we must next determine whether greenhouse gases are
“agent[s]” of “air pollution.” If so, the statute would authorize
regulation; if not, EPA would lack authority. Unlike “air
pollutants,” the term “air pollution” is not itself defined by the
CAA; thus, once again we must accept EPA’s interpretation of that
ambiguous term, provided its interpretation is a “permissible
construction of the statute.” Chevron , 467 U. S., at 843.
In this case, the petition for rulemaking asked EPA for “regulation
of [greenhouse gas] emissions from motor vehicles to reduce the
risk of global climate change.” 68 Fed. Reg. 52925. Thus, in
deciding whether it had authority to regulate, EPA had to determine
whether the concentration of greenhouse gases assertedly
responsible for “global climate change” qualifies as “air
pollution.” EPA began with the commonsense observation that the
“[p]roblems associated with atmospheric concentrations of
CO 2,” id., at 52927, bear little
resemblance to what would naturally be termed “air
pollution”: “EPA’s prior use of the CAA’s general
regulatory provisions provides an important context. Since the
inception of the Act, EPA has used these provisions to address air
pollution problems that occur primarily at ground level or near the
surface of the earth. For example, national ambient air quality
standards (NAAQS) established under CAA section 109 address
concentrations of substances in the ambient air and the related
public health and welfare problems. This has meant setting NAAQS
for concentrations of ozone, carbon monoxide, particulate matter
and other substances in the air near the surface of the earth, not
higher in the atmosphere… . CO 2, by
contrast, is fairly consistent in concentration throughout the
world’s atmosphere up to approximately the lower stratosphere.” Id., at 52926–52927. In other words, regulating the buildup of CO 2
and other greenhouse gases in the upper reaches of the atmosphere,
which is alleged to be causing global climate change, is not akin
to regulating the concentration of some substance that is polluting the air . We need look no further than the dictionary
for confirmation that this interpretation of “air pollution” is
eminently reasonable. The definition of “pollute,” of course, is
“[t]o make or render impure or unclean.” Webster’s New
International Dictionary 1910 (2d ed. 1949). And the first three
definitions of “air” are as follows: (1) “[t]he invisible,
odorless, and tasteless mixture of gases which surrounds the
earth”; (2) “[t]he body of the earth’s atmosphere; esp., the part
of it near the earth, as distinguished from the upper rarefied
part”; (3) “[a] portion of air or of the air considered with
respect to physical characteristics or as affecting the senses.” Id. , at 54. EPA’s conception of “air pollution”—focusing
on impurities in the “ambient air” “at ground level or near the
surface of the earth”—is perfectly consistent with the natural
meaning of that term. In the end, EPA concluded that since “CAA
authorization to regulate is generally based on a finding that an
air pollutant causes or contributes to air pollution,” 68 Fed. Reg.
52928, the concentrations of CO 2 and other
greenhouse gases allegedly affecting the global climate are beyond
the scope of CAA’s authorization to regulate. “[T]he term ‘air
pollution’ as used in the regulatory provisions cannot be
interpreted to encompass global climate change.” Ibid .
Once again, the Court utterly fails to explain why this
interpretation is incorrect, let alone so unreasonable as to be
unworthy of Chevron deference. *  *  * The
Court’s alarm over global warming may or may not be justified, but
it ought not distort the outcome of this litigation. This is a
straightforward administrative-law case, in which Congress has
passed a malleable statute giving broad discretion, not to us but
to an executive agency. No matter how important the underlying
policy issues at stake, this Court has no business substituting its
own desired outcome for the reasoned judgment of the responsible
agency. Footnote
1 The Court’s way of
putting it is, of course, not quite accurate. The issue is whether
it would be better to defer the decision about whether to
exercise judgment. This has the effect of deferring
regulation but is quite a different
determination. Footnote
2 Not only is EPA’s
interpretation reasonable, it is far more plausible than the
Court’s alternative. As the Court correctly points out, “all
airborne compounds of whatever stripe,” ante , at 26, would
qualify as “physical, chemical, . . . substance[s] or matter which
[are] emitted into or otherwise ente[r] the ambient air,” 42 U.
S. C. §7602(g) . It follows that everything airborne, from Frisbees to flatulence, qualifies as an “air
pollutant.” This reading of the statute defies common
sense.

Summary: The Supreme Court ruled that the Environmental Protection Agency (EPA) has the authority to regulate carbon dioxide and other greenhouse gas emissions from new motor vehicles under the Clean Air Act. The Court found that the EPA's previous refusal to regulate these emissions was based on an unreasonable interpretation of the Act. The Court also determined that at least one petitioner had standing to bring the case, given the serious and pressing nature of global warming.