Climate “Endangerment”

and bad arguments

The Trump administration's reported determination to overturn the EPA's 2009 endangerment finding on climate change would be extremely difficult — but not impossible, experts tell Axios.

Why it matters: The EPA finding — long a target of conservatives —underpins a slew of regulations on cars, trucks and power plant emissions.

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Yes, but: Greenstone said an effort to overturn the finding would have to ignore the mounting signs that climate change is already harming current generations.

"It seems a bizarre position, given the record global temperatures, the fires in California, the unheard of hurricane storm in North Carolina," he said. "It seems a strange moment in time to be arguing that greenhouse gases don't endanger the public health and welfare."

The intrigue: Phil Duffy, chief scientist at Spark Climate Solutions who served in the Biden administration's Office of Science and Technology Policy, said overturning the finding requires doing two things.

First,"you have to somehow prove that all of the effects that we're seeing of climate change are not caused by greenhouse gases," Duffy told Axios in an interview.

"And then you also have to provide some other alternative explanation for all the changes in climate and all the societal impacts," he said. "It seems like an incredibly high bar."

Duffy was also the lead author of a 2019 study in the journal Science updating the scientific evidence for the finding. (Axios)

Both Greenstone and Duffy fail to distinguish between the claim that climate change has some negative effects and the claim that its net effect is negative. Any substantial change has some negative effects; to argue for government action to prevent a change you need to show that the net effect is negative, that costs are greater than benefits. Hence to argue against such policies one does not, as Greenstone and Duffy assert, have to claim that the negative effects do not exist, only that they are at least balanced by positive effects.¹]

The Axios quotes from Greenstone and Duffy suggest that either they do not realize this or are confident there are no positive effects of climate change to set against its costs.

For more evidence I read Duffy’s article in Science. Figure 1 of the article shows areas where the evidence for adverse effects of climate change has or has not gotten stronger, does not mention positive effects.

The article’s list of temperature extremes:

For extreme event attribution in North America, this includes more than 70% of recent record-setting hot, warm, and wet events and ~50% of record-setting dry spells (12), along with the recent California drought (13, 14), the storm-surge flooding during Superstorm Sandy (15) and Hurricane Katrina (16), and heavy precipitation during Hurricane Harvey (17–19).

Notably missing is the decreased frequency of extreme cold, although mortality from below optimal temperatures, as reported in a series of Lancet articles, is much larger than from above optimal temperatures² and the increase in minimum temperatures due to climate change, as shown in the IPCC reports, is in most times and places larger than the increase in maximum temperatures.

The only mentions of positive effects I could find in the article:

There is still an expectation that certain aspects of increasing CO₂ and temperature will be beneficial in the next few decades for some crops and locations within the United States but that these positive effects are likely to be outweighed by negative impacts, especially in the long term.

…

Whereas CO₂ fertilization, warming-induced lengthening of the growing season, and nitrogen deposition pose potential benefits to trees, models substantially overestimate CO₂-driven increases in global vegetation productivity over recent decades

The article correctly observes that warming is greater in the arctic, discusses only negative consequences of that pattern. There is no mention of the fact that human land use at present is limited by cold, not heat, as can be seen by comparing a population density map of the globe to an average or maximum temperature graph, hence that warming can be expected to substantially increase the habitable area of the globe.³

I have discussed at considerable length in past posts effects of climate change, the literature on the subject and the question of whether the net effect is positive or negative. My conclusion was and is that we do not know, that there are both positive and negative effects and their size is too uncertain to sign the sum. What struck me about the Axios story was that neither the author nor the academics quoted appeared to have thought about that question.⁴ The arguments they attributed to hypothetical opponents were straw men. Either those were the only arguments for reversing the endangerment finding that they could think of or they preferred not to mention the existence of better ones.

Readers may reasonably respond that although the argument offered by Greenstone and Duffy is wrong their conclusion is right, as demonstrated by the scientific consensus supporting the claim that climate change is bad. I offered evidence that that consensus cannot be trusted in an earlier post.

How could a mistaken scientific consensus arise? Part of the answer is that each participant bases his conclusion almost entirely on the work of others, adds only a grain of sand to the metaphorical beach. If all participants start out believing in the same right answer each will be inclined to bias his part of the work in the direction that supports that answer and the combined effect will confirm the belief that supports the bias. That is particularly likely in a field such as this, sufficiently complicated so that any conclusion depends on multiple judgement calls — all being made in the same direction. It isn’t as if there is some test of the consensus conclusion, some climate science equivalent of the Michelson-Morley experiment, that could prove the sign of the net effect of climate change.

To see how a mistaken consensus could be maintained imagine, very improbably, that my arguments convince Greenstone or Duffy that there is no good reason to expect climate change to have net bad effects and he publishes that conclusion. He would be converted in the eyes of friends and colleagues from a respectable academic to the climate equivalent of a biologist who rejects evolution, a nut case, a “denier,” would suffer very large costs, social and professional. It is prudent to avoid pursuing lines of thought or research that might lead to such consequences.

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1. The relevant legislation is the Clean Air Act. Its definition of what it regulates is:

§7408. (a) (1) (A) For the purpose of establishing national primary and secondary ambient air quality standards, the Administrator shall within 30 days after December 31, 1970, publish, and shall from time to time thereafter revise, a list which includes each air pollutant—emissions of which, in his judgment, cause or contribute to air pollution which may reasonably be anticipated to endanger public health or welfare;

An emission whose benefits at least balance its costs does not endanger public health or welfare.

2. Zhao et. al. 2021 finds, from 2000 to 2019, a decrease in net mortality due to temperature, mortality from cold declining more than mortality from heat increased. I discuss, and to some degree critique, the relevant literature in two posts. For a more detailed critical account of the literature see Human Deaths from Hot and Cold Temperatures and Implications for Climate Change.

3. I offer an estimate of the size of the effect in an earlier post. If my calculations are correct, a 3°C increase in average temperature would increase the area of the globe warm enough for habitation by about the current area of the United States, between two and three orders of magnitude more than the area lost through sea level rise.

4. Relevant work by Greenstone is at https://michaelgreenstone.com/research/?ucterms=category:climate-change-and-scc. It includes one 2004 piece coauthored by Greenstone predicting a positive effect of climate change on American agriculture. As best I could tell, all of the others took it for granted that effects are negative, discussed at most how negative.