Alex Epstein was kind enough to send me a copy of his book, Fossil Future. Unfortunately, I cannot recommend it. Readers looking for a book that seriously considers the benefits as well as the risks of fossil fuel use should consider, for example, A Question of Balance, by Nobel Prize winning economist William Nordhaus.

Although there are a few random postscripts at the end of this post, I want to focus on two specific claims from Epstein’s book, both of them related to his argument that there are “massive, system-wide distortions in the climate knowledge system’s evaluation of CO2’s climate impacts” (p296). First, he claims that IPCC Summaries for Policymakers are “deliberately dishonest summaries” (p317) of the underlying reports themselves. Second, he claims that the IPCC (among others) suffers from “systematic ‘CO2 benefit denial'”, of which the “most egregious instance” is “the well-established ‘fertilizer effect'” (p297).

Before we begin, let’s look at what Epstein says is the first of  “four standards of objective explanation I use when validating climate claims”:

1. They give clear explanations of the evidence for their views rather than just invoking authority. I take seriously only sources that clearly explain what their evidence is. If they pronounce authoritative claims without evidence, I suspect their goal is something other than generating an understanding of the truth. (p316-317, boldface in original)

Epstein’s claim about IPCC Summaries for Policymakers

Let’s look at Epstein’s first claim, which is that IPCC Summaries for Policymakers are distortions of the underlying IPCC reports themselves:

One way to catch major distortions of synthesized research by disseminators is to review, even briefly, the synthesis that they are claiming to report on. If you do this with the actual IPCC synthesis reports, you will likely be shocked by how badly they are distorted by mainstream disseminators, including the IPCC’s own disseminator document, the Summary for Policymakers. (p14)

Further catastrophizing occurs in disseminating the findings of the reports to the general public, which is done in a manner that wildly distorts what even the biased reports say. One of the key mechanisms of distortion is the IPCC’s Summary for Policymakers, which is used to identify takeaways from the multithousand-page reports that almost no one reads. Numerous participants in the assessment reports have complained over the years that these summaries are wild overstatements of the reports’ negative conclusions. (p307)

Epstein also refers to this issue elsewhere, but the two pages cited above appear to be the only places where he has citations or otherwise attempts to provide evidence.

The evidence he provides there is, judging by his own standards, incredibly weak. Both pages reference complaints by one person (economist Richard Tol), and instead of actually citing what Tol wrote, Epstein relies on a second-hand description in a book by Michael Shellenberger called Apocalypse Never. (This reliance on secondary sources has gotten Epstein into trouble elsewhere: on Twitter he acknowledges that he made an error in asserting that climate scientist Jim Hansen’s predictions were “shockingly wrong” [p44], an error that stemmed from mistakes in a 1986 article in the NY Times.)

So here’s what we’ve got:

  1. Epstein says that “[n]umerous participants” have complained. As evidence he offers up one person. This is weak.
  2. Epstein doesn’t even directly cite that one person (Richard Tol), instead citing and quoting a book (Shellenberger’s) that includes a section on Tol.
  3. The dangers of relying on secondary sources are clear from Epstein’s own mistakes, and from Shellenberger’s as well: in his section on Tol, Shelleberger claims (p255) that “In 2010, an IPCC Summary falsely claimed climate change would result in the melting of the Himalayan glaciers by 2035.” This is the infamous Himalayan glacier mistake, but it was a mistake in the underlying report, not in the Summary for Policymakers.
  4. As suggested by the infamous Himalayan glacier mistake, Epstein’s claim that the IPCC produces “multithousand-page reports that almost no one reads” is both obviously true and a bizarre twisting of reality. Enough people read them that there was a huge uproar about one mistake in a 938-page document!
  5. Similarly bizarre (but IMHO not at all true) is Epstein’s claim that IPCC Summaries are “wild overstatements” and “major distortions” of the underlying reports themselves.
  6. Epstein’s own rules are that he should be “giving clear explanations of the evidence… rather than just invoking authority” and that if someone claims to “pronounce authoritative claims without evidence, I suspect their goal is something other than generating an understanding of the truth.”

Bottom line: Epstein should provide clear evidence that IPCC Summaries are “wild overstatements” and “major distortions” of the underlying reports themselves. He claims this is easy to do if you “review, even briefly,” the Summaries and their underlying reports. Okay, go ahead Alex, let’s see it. I challenge you to provide three concrete examples (preferably from IPCC AR6, but earlier reports are fine as well) where the Summaries for Policymakers (SPMs) are “major distortions” of the underlying reports themselves. Note that we are talking about a very specific and presumably very simple issue: we’re not talking about the SPMs majorly distorting what Epstein or Tol or Shellenberger or I or anybody else may think are important issues, we’re talking about the SPMs majorly distorting the underlying IPCC reports!

Epstein’s claim about the “fertilizer effect”

Epstein’s second claim is that the IPCC (among others) suffers from “systematic ‘CO2 benefit denial'”, of which the “most egregious instance” is “the well-established ‘fertilizer effect'” (p297). I’m going to quote pages 296-302 of Epstein’s book at length because this whole claim turns out to be completely off-base:

In the next sections I will document massive, system-wide distortions in the climate knowledge system’s evaluation of CO2’s climate impacts… These distortions fall into two major categories [the first of which is] the “CO2 benefit denial” distortion…

The CO2 benefit denial distortion [Boldface in original]

…CO2 is both a warming gas and a fertilizing gas. One minute of commonsense thinking about the effects of rising levels of such a gas should lead to the expectation that it will have at least some significant positive impacts… And yet our knowledge system fails to seriously consider these benefits of CO2. I don’t merely mean that knowledge-dissemination institutions like The New York Times or The Washington Post fail to. I mean that the entire system, from research funding to synthesis by the IPCC to dissemination by The New York Times, fails to. The most egregious instance of systematic “CO2 benefit denial” is with regard to the well-established “fertilizer effect.” It has been well-established that when you increase the amount of CO2 in the atmosphere, as happens when we burn fossil fuels, plants grow more because CO2 is plant food. [Boldface added]

…Even if the benefits of “global greening” from rising CO2 levels are outweighed by negatives, they have clearly still had massive positive impacts, including likely trillions of dollars’ worth of crop-growing benefits. Those positive impacts certainly deserve extensive study and dissemination. And yet these extremely positive plant-growth effects of CO2 are systematically denied by our knowledge system—including at the root of our knowledge system: decisions about research.

…[W]hen research is distorted to ignore the benefits of fossil fuels, the rest of the knowledge system will follow—including synthesis, where the IPCC downplays the extremely significant potential of global greening for human flourishing, and dissemination, where the IPCC’s latest Summary for Policymakers doesn’t even mention the benefits of greening at all.

…The benefits of warming are a very rare subject for climate research, almost completely ignored by IPCC synthesis reports, and completely ignored by IPCC Summaries for Policymakers as well as most other disseminators of climate “knowledge.” A climate knowledge system that denies the possibility of the massive plant-growth and warming benefits of CO2 is a system that cannot be trusted.

I say this is completely off-base because IPCC AR6 does in fact address the fertilizer effect (boldface added throughout):

  1. Here’s text from the IPCC AR6 WGII Technical Summary: “Increased CO2 concentrations promote crop growth and yield but reduce the density of important nutrients in some crops (high confidence) with projected increases in undernutrition and micronutrient deficiency, particularly in countries that currently have high levels of nutrient deficiency (high confidence) and regions with low access to diverse foods (medium confidence).”
  2. Go take a look at IPCC AR6 WGII Figure TS.6 FOOD-WATER. (The direct link here appears to be partially broken.) The caption notes that “Projected impacts are for RCP4.5 mid 21st century, taking into account adaptation and CO2 fertilisation for the crop yield productivity.”
  3. Here’s a link to IPCC AR6 WGII Figure 5.6, titled “Projected yield changes relative to the baseline period (2001–2010) without adaptation and with CO2 fertilisation effects (Hasegawa et al., 2021b).” There are some details is IPCC AR6 WGII Figure 5.7, which has the same title: “Projected yield changes relative to the baseline period (2001–2010) without adaptation and with CO2 fertilisation effects (Hasegawa et al., 2021b).”
  4. Here’s the text in IPCC AR6 WGII Chapter 5 that accompanies Figure 5.6: “The impact of climate change on crop yield without adaptation projected in the 21st century is generally negative even with the CO2 fertilisation effects, with the overall median per-decade effect being −2.3% for maize, −3.3% for soybean, −0.7% for rice and −1.3% for wheat, which is consistent with previous IPCC assessments (Porter et al., 2014).”
  5. Here’s a link to IPCC AR6 WGII Figure 5.8, titled “Synthesis of literature on the projected impacts of climate change on different cropping systems.” Let me show you that figure, note that it has a column for “Carbon dioxide”:

Now, you might say that all this isn’t fair because IPCC AR6 WGII might have come out after Epstein’s book came out in 2022. In other words, maybe the IPCC folks suddenly changed their minds and decidedly to belatedly study something that should have been immediately obvious after “one minute of commonsense thinking.” But the bit in #4 above about “previous IPCC assessments (Porter et al., 2014)” suggests something that in fact turns out to be true: the previous IPCC report (AR5) also addressed the fertilizer effect (again, boldface added throughout):

  1. Check out IPCC AR5 WGII Figure 7-4. The full chapter contains the caption, which includes this: “Dots indicate where a known change in atmospheric CO2 was used in the study; remaining data are indicated by x. Note that differences in yield value between these symbols do not measure the CO2 fertilization effect, as changes in other factors such as precipitation may be different between studies.”
  2. Better yet, take a look at IPCC AR5 WGII Table 7-3, which I will reproduce here because it specifically identifies CO2 fertilization as one of six “climate-related driver of impacts”:

Now, let’s look at what Epstein says (p316) is the fourth of  “four standards of objective explanation I use when validating climate claims”:

4. They legitimately engage and address competing viewpoints, without evading, demonizing, or straw-manning them… Some questions I find helpful to ask… are: Do they acknowledge the intelligent people who disagree with them—or do they write them off as immoral or stupid? …Do they represent dissenting views accurately—or do they smear them?” [See also p320.]

Epstein totally fails to meet his own standard here. He doesn’t engage with any of this material from AR6 or AR5, instead writing off the IPCC and its contributors.

Also noteworthy is that his entire section on “The ‘CO2 Benefit Denial’ Distortion” has only six citations, none of which are capable of carrying the weight of Epstein’s accusations of “massive, system-wide distortions”:

  1. One of those citations pertains to something Svante Arrhenius wrote in 1908.
  2. A second citation pertains to something Svante Arrhenius apparently wrote in 1913. (I say “apparently” because Epstein quotes second-hand from a 2019 blog post.)
  3. A third citation presents what Epstein claims to abhor—“authoritative claims without evidence”—by quoting four paragraphs that physicist Freeman Dyson apparently wrote as a preface to a book published in 2015. These paragraphs touch on the CO2 fertilization effect but are mostly noteworthy because Dyson makes the odd claim that the US DOE “fixed the agenda of official discussions of carbon dioxide” in 1978.  (Like Epstein, Dyson doesn’t seem to have read AR5… but since he died in 2020 he shouldn’t be faulted for skipping AR6!)
  4. A fourth citation is to the Summary for Policymakers from IPCC AR6 WGI, which Epstein bizarrely says “doesn’t even mention the benefits of greening at all.” This is bizarre because WGI is about climate science and not about costs or benefits at all. Also, the document in question does in fact cover the scientific aspects of greening, e.g., in the sections on land sinks.
  5. A fifth citation is to two NASA reports that “global greening” is happening; again, this is reported in IPCC AR6 WGI.
  6. The sixth and final citation is to a non-peer-reviewed paper that is over 10 years old (published in 2012).

Bottom line: Epstein’s “most egregious instance” of “systematic ‘CO2 benefit denial'” is terribly flawed.  Readers deserve more, especially from a project with a “rather massive R&D budget” (p432).

Random postscripts

  1. Epstein is a philosopher, and maybe that’s behind his desire to categorize things, especially as Good or Bad. I’m an economist, and economists like to “think at the margin”, meaning that we tend to ask questions along the lines of “should we do a little more of x?” (See my comedy routine about this.) My comment here is that I think that Epstein should do a little more thinking at the margin. (Or maybe a lot more!) His arguments might be stronger, especially his claim (p38) to be able to “teach [us] how to think more clearly.” For example, he talks about “the guaranteed catastrophe of restricting fossil fuel use” (p249), but surely restricting fossil fuel by some tiny amount (e.g., a reduction from baseline of 0.0001%) is not going to cause catastrophe?
  2. Epstein seems to be making the case to oppose just about any and all climate policies, but he doesn’t seem to recognize the risks of this strategy, so it’s worth taking a look at recent developments in Washington State. In 2016 I was the founder and co-chair of I-732, which put a revenue-neutral carbon tax on the ballot that aimed to offset the pocketbook impacts of a carbon tax with reductions in other taxes, mainly a 1-cent reduction in the state sales tax. I-732 lost because of what I describe as opposition from folks on the right who were afraid that our policy was socialism and opposition from folks on the left who were mad that it wasn’t. In 2018 the “environmental left” put their own Green New Deal-ish measure on the ballot (I-1631) and it also lost. Then in 2020 the Democrats gained control of both chambers in the state legislature and passed the Climate Commitment Act, a “cap-and-invest” bill that in many ways is similar to I-1631. That bill went into effect in January 2023 and has arguably raised gas prices by 30-50 cents per gallon. There is now a ballot measure (I-2117) to repeal the CCA, but it’s probably an uphill battle. So, Alex, if we could have a do-over on I-732 (and we might if the CCA repeal wins!) then don’t you think you should support it? Or are you going to keep saying No to everything even though that could well lead to policies that (unlike I-732) are not pocketbook-friendly and not small-government?
  3. On pages 85-86 Epstein accuses US Treasury Secretary Janet Yellen of making “incoherent arguments.” He doesn’t include a citation here (!), but a Google search turns up this speech in which Yellen says that “Our financial system must… be prepared for the best-possible case scenario: that we begin a rapid transition to a net-zero carbon economy”. Although it’s possible to read this in the way that Epstein apparently does, namely that Yellen is just another fanatic who’s ready to sacrifice the global economy in order to cut CO2, it’s also possible to read this in a more friendly way, namely that Yellen’s “best-possible case scenario” is that renewables rapidly get better and out-compete fossil fuels, delivering cheap, low-carbon energy for the whole world. So… I think Epstein should be a little less quick to accuse Janet Yellen—along with “countless others”, mind you—of making incoherent arguments.
  4. My fourth random postscript is about a bet I’ve made recently that I encouraged Epstein to join… on my side! It’s the second climate bet I’ve made. (The first is about whether there’s a “pause” in global temperature increases, and I’m winning that bet because global temperatures continue to increase.) This second climate bet is about the trend in four categories of fossil CO2 emissions (coal, oil, natural gas, and all three combined), and here I’m betting that all four will reach new highs in 2030 or 2031, i.e., will not peak this decade. I’d be happy to be proved wrong because renewables are so cheap and so great, but, well, like Epstein (p203) I just don’t think it’s likely that renewables are up to the task of “providing so much cost-effective energy that there is actually a decline in fossil fuel use despite growing energy needs.” Epstein calls this “incredibly improbable… virtually no possibility” (p204) so my comment here is just that I’m surprised he didn’t join the bet.
  5. Since Epstein approvingly cites Shelleberger’s book (Apocalypse Never, 2020), I wanted to quote something from pp251-252 of that book: “[Economist Thomas] Schelling’s view was simply that the effects of restricting energy consumption could be worse than the effects of global warming. That view was mainstream back then and remains so today. Indeed, it is at the heart of the discussions of climate mitigation in reports by the Intergovernmental Panel on Climate Change (IPCC)… and other scientific bodies.” (Boldface added.) This seems to directly contradict the thesis of Epstein’s book, so it would have been great to have been able to focus on issues like this. Unfortunately, we (or at least I) must give priority to questions about the intellectual foundations and academic integrity of Epstein’s book.