Is EPA Administrator Scott Pruitt planning to terminate all EPA regulation of greenhouse gases?   Perhaps.  Pruitt’s cagey refusal to admit that carbon dioxide is a “primary contributor to . . . global warming” suggests the Trump EPA may be plotting a full-frontal assault on greenhouse-gas regulation.

But can Pruitt’s EPA so easily discard its duty to regulate greenhouse gases?  Probably not.

A bit of background: Over the past eight years, EPA—acting pursuant to its authority under the Clean Air Act—has constructed a multi-pronged edifice for controlling greenhouse-gas emissions.  Among other things, EPA has issued rules regulating greenhouse-gas emissions from motor vehicles, aircraft, and power plants, as well as from other “stationary” pollution sources like steel mills and cement kilns. 

That regulatory edifice, however, is constructed atop a single foundation: EPA’s 2009 Endangerment Finding.  Promulgated in response to the Supreme Court’s decision in Massachusetts v. EPA—in which the Court held that greenhouse gases qualify as “air pollutants” subject to regulation under the Clean Air Act—the Endangerment Finding constituted EPA’s baseline determination that greenhouse gases “may reasonably be anticipated to endanger public health or welfare.”  That determination, in turn, obligated EPA to regulate greenhouse gases across multiple industries.

Because the Endangerment Finding is the linchpin for all ensuing greenhouse gas regulation, undoing it has long been a goal of climate-change deniers. Get rid of the Endangerment Finding, the theory goes, and subsequent greenhouse-gas regulations will necessarily fall.  And some prominent climate-change deniers (like Trump advisor Myron Ebell) believe that Pruitt’s recent comments about carbon dioxide indicate the Endangerment Finding is now in EPA’s crosshairs.

It’s easy to see why the Myron Ebells of the world think that the Endangerment Finding might be undone.  For one, the statutory section under which the Endangerment Finding was issued appears to give Pruitt a fair amount of discretion.  Specifically, the statute instructs EPA’s Administrator to regulate air pollutants which “in his judgment . . . cause, or contribute to, air pollution which may reasonably be anticipated to endanger public health or welfare.”  What is more, the question whether a pollutant is dangerous is, quintessentially, the type of scientific question EPA exists to answer. For these reasons, a reviewing court would likely apply a deferential standard of review to any EPA order revisiting the Endangerment Finding—perhaps vacating a revision only if it was “arbitrary, capricious, an abuse of discretion, or not otherwise in accordance with the law.”[1] 

But EPA’s authority to undo the Endangerment Finding is far more circumscribed than it appears at first blush.  That is true for at least three interlocking reasons.

First, when making—or rescinding—an endangerment finding, EPA’s inquiry must begin and end with science. In Massachusetts, the Supreme Court instructed that the sole relevant consideration for the Endangerment Finding was “whether greenhouse gases cause or contribute to climate change.”  EPA thus cannot rescind the Endangerment Finding because it thinks the costs of regulation are too high, or because it believes climate change is better addressed through other means.  (Indeed, the Court in Massachusetts chastised the Bush EPA for attempting to avoid greenhouse-gas regulation on the basis of such “policy” concerns.)  An endangerment finding, the Supreme Court emphasized, must be based upon EPA’s “scientific judgment.” 

Second, the Clean Air Act requires the Administrator to make an endangerment finding if he concludes that emissions “may reasonably be anticipated to endanger public health or welfare.” Thus, so long there is even a “reasonable” probability that—in the Supreme Court’s words—“greenhouse gases cause or contribute to climate change,” EPA must issue an endangerment finding.  The obvious flipside: to undo the Endangerment Finding, EPA must make a “scientific judgment” that there is not even a “reasonable” probability greenhouse gases “cause or contribute to climate change.”

Against that backdrop, the crucial third point:  Scientifically speaking, there is much, much more than a “reasonable” probability that greenhouse gas emissions cause climate change.  Indeed, the scientific evidence connecting greenhouse-gas emissions with climate change is overwhelming.  That was true when EPA issued the Endangerment Finding in 2009, and it is even truer today.  To take but one example: when EPA issued the Endangerment Finding, it relied in large part on a 2007 report from the Intergovernmental Panel on Climate Change (IPCC). That IPCC report—which considered volumes of published climate-science literature—concluded that there was a 90% chance that human emissions of greenhouse gases caused most of observed global warming since the mid-20^th century.  In 2013, IPCC revised that estimate upwards, to 95% certainty. And the IPCC report is merely one data point (albeit a very important one).  Study after study has concluded that an overwhelming majority of scientists believe human emissions of greenhouse gases are responsible for climate change.

Given that overwhelming scientific consensus, it is unlikely that Scott Pruitt’s EPA could make a straight-faced “scientific judgment” that there is not even a reasonable possibility that “greenhouse gases cause or contribute to climate change.”  That is not to say that Pruitt won’t try.  There is no shortage of outlier studies which question the connection between greenhouse-gas emissions and climate change.  In seeking to undo the Endangerment Finding, the EPA could well seek to promote such studies—knowing that any revision of the Endangerment Finding is likely to receive deferential judicial review.

But deferential judicial review is still actual review.  And at some point, a purportedly “scientific” EPA determination that flies in the face of an established scientific consensus must be struck down as an abuse of agency discretion. Compounding matters, Pruitt and Trump’s documented hostility towards climate science could come back to haunt them.  Just as Trump’s campaign statements about a “Muslim Ban” gives rise to an inference that his “travel bans” were enacted with discriminatory intent, his off-the-cuff statements that climate change is a Chinese hoax could convince a reviewing court that a rescission of the Endangerment Finding was preordained—not reflective of EPA’s reasoned “scientific judgment.” 

Science, in short, is not a realm for “alternative facts.”  And because science is the Endangerment Finding’s lodestar—and because the connection between greenhouse-gas emissions and climate change is scientifically well-established—any attempt to undo the Endangerment Finding is likely to be legally suspect.

[1] EPA’s issuance of an endangerment finding is plainly subject to such “arbitrary and capricious” review—the United States Court of Appeals for the D.C. Circuit upheld the Endangerment Finding under precisely that standard.  I hedge only a bit on the question what standard of review would apply to the rescission of an endangerment finding, as I am not aware of any previous EPA action to rescind an endangerment finding.   

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