The DOE Report: A Case Study in Scientific Misrepresentation

WNA Heat Dome from Bercos-Hickey et al 2022

In preparing my previous post on my initial response to the DOE report, I stumbled on the report's assessment of Western North America heat dome in June 2021, and I discovered several ways in which the authors misrepresented the scientific research they used to support their position. It turns out in many ways I was just scratching the surface of the problems with their analysis of this event. Their assessment comes from pp. 96 and 97 of the DOE report, and it is structured as a rebuttal to a "rapid attribution analysis" that was published in Philip et al 2022.[1] This is their summary of that analysis:

The WWA team generated international headlines with their analysis, which provided the following attribution statements (WWA, 2021; Philip et al., 2022):

• Based on observations and modeling, the occurrence of this heatwave was virtually impossible without human-caused climate change.
• The event is estimated to be about a one in 1000-year event in today’s climate.
• The event would have been at least 150 times rarer without human-induced climate change.
• This heatwave was about 2°C hotter than it would have been if it had occurred at the beginning of the industrial revolution (when global mean temperatures were 1.2°C cooler than today).

This is a mostly accurate summary of the abstract of the paper, though without the caveats the authors had written. The paper's abstract says,

The observed temperatures were so extreme that they lay far outside the range of historical temperature observations. This makes it hard to state with confidence how rare the event was. Using a statistical analysis that assumes that the heat wave is part of the same distribution as previous heat waves in this region led to a first-order estimation of the event frequency of the order of once in 1000 years under current climate conditions. Using this assumption and combining the results from the analysis of climate models and weather observations, we found that such a heat wave event would be at least 150 times less common without human-induced climate change. Also, this heat wave was about 2°C hotter than a 1-in-1000-year heat wave would have been in 1850–1900, when global mean temperatures were 1.2°C cooler than today. Looking into the future, in a world with 2°C of global warming (0.8°C warmer than today), a 1000-year event would be another degree hotter.

Rapid attribution analysis is designed to be "rapid" and therefore preliminary. We would expect these initial results to be updated and improved with later analysis, so the authors point out that this was a "first-order estimation" based on an analysis that found it very difficult to state with confidence how rare the event actually was. The text of the paper adds additional context regarding the uncertainties in the methodology, particularly with regard to generalized extreme value (GEV) distribution analysis: 

Further research is planned to investigate whether these or other feedbacks were operating in this exceptional event, whether those feedbacks are related to human-induced climate change, and whether they increase the frequency beyond that expected for random events of such extreme temperatures. Also, further research is needed to overcome the known limitations of standard GEV analysis on annual maxima with short records and very extreme values.

The original pre-published report from 2021 also acknowledged uncertainties are still very large concerning the likelihood of the conditions that caused the the heat dome event vs how much hotter this event was because of AGW:

Based on this first rapid analysis, we cannot say whether this was a so-called “freak” event (with a return time on the order of 1 in 1000 years or more) that largely occurred by chance, or whether our changing climate altered conditions conducive to heatwaves in the Pacific Northwest, which would imply that “bad luck” played a smaller role and this type of event would be more frequent in our current climate.

This is an important distinction that the DOE report appears to conflate. It's possible that AGW has not altered the conditions that caused the formation of the WNA heat dome while at the same time AGW can make those events hotter when they occur.

It's an open question to me whether these kinds of rapid attribution studies are helpful (I'm not sure we need to know the attribution right away), and certainly these kinds of studies can be misrepresented in the media, sharing how extreme this event was without the caveats included in the paper. But clearly the fact that the media did this in 2021 is not an excuse for the DOE report doing this at all, certainly not in 2025, and the DOE report clearly pits the findings of this initial study against later analysis, which they present as countering the claims of Philip et al. The DOE report claims:

But an important counter to the first claim is that other researchers concluded from historical weather data that while a heat wave of the magnitude observed was indeed virtually impossible without anthropogenic climate change, it was also virtually impossible with climate change. Bercos-Hickey (2022) noted “these temperatures were virtually impossible under any previously experienced meteorological conditions, with or without global warming.” McKinnon and Simpson (2022) stated “the most likely explanation remains that the weather event itself was ‘bad luck.’” The 2023 Oregon Climate Assessment (Fleischman, 2023) concluded that the heat dome would have formed even without climate change and “There is no evidence that the highly unusual combination of weather features that drove the heat dome were made more likely by climate change, and climate models do not project an increase in the frequency of high-pressure ridges over the Pacific Northwest” (Fleischman, 2023, p. 49).

The argument here is that these later studies and reports have countered or corrected the initial analysis. The DOE report then presents itself as siding with this later analysis as if it's a rebuttal to the initial report. I've looked up the studies and reports mentioned in this paragraph, and it seems very clear that the DOE report has to varying degrees mishandled every single one of these later studies and reports. Let's look at each study and compare what the DOE report says about these studies to what the studies actually say.

Study 1 - Bercos-Hickey (2022)[2]

"Bercos-Hickey (2022) noted 'these temperatures were virtually impossible under any previously experienced meteorological conditions, with or without global warming.'" 

While it's true that this quote comes from that paper, it's also true that Bercos-Hickey's paper is doing exactly what Philip et al was saying needs to be done - evaluate the limitations for the standard GEV analysis. But the conclusions from Bercos-Hickey et al remain fairly compatible with Philip et al. They write in the abstract,

Multiple causal factors, including anthropogenic climate change, contributed to these high temperatures, challenging traditional methods of attributing human influence. We demonstrate that the observed 2021 daily maximum temperatures are far above the bounds of Generalized Extreme Value distributions fitted from historical data. Hence, confidence in Granger causal inference statements about the human influence on this heatwave is low. Alternatively, we present a more conditional hindcast attribution study using two regional models. We performed ensembles of simulations of the heatwave to investigate how the event would have changed if it had occurred without anthropogenic climate change and with future warming. We found that global warming caused a ∼0.8°C–1°C increase in heatwave temperatures. Future warming would lead to a ∼5°C increase in heatwave temperature by the end of the 21st century.

In other words, despite the limitations of GEV distribution analysis, AGW contributed to these high temperatures, making them about 0.8°C–1°C warmer than what they would have been, and they may potentially become 5°C warmer by the end of the 21st century. Now to their credit, on p. 97 the DOE report repeats some of this and even admits that Bercos-Hickey et al found that "human activities caused a ∼1.4°F– 1.8°F increase in the daily maximum temperatures." But they do not acknowledge the paper's conclusion that AGW will continue to make these heatwaves worse through the 21st century as carbon emissions continue. Bercos-Hickey writes, "In contrast, the heatwave in an SSP585 world with significant future warming would be 5°C warmer, and the anthropogenic influence extends the peak of the heatwave, indicating a future increase in heatwave duration." Even with SSP5-8.5 being extremely unlikely, these events are likely to become more frequent in the future with continued emissions.

Study 2 - McKinnon and Simpson (2022)[3]

"McKinnon and Simpson (2022) stated 'the most likely explanation remains that the weather event itself was ‘bad luck.'" 

While it's true that this quote from McKinnon and Simpson (2022) does appear in the report, that's not an honest summary of the paper's position. The paper found that, while heatwaves like the 2021 WNA heat dome could be reproduced in climate models, "they are rare: temperature anomalies that exceed 4.5σ occur with an approximate frequency of one in a hundred thousand years." They also conclude, "While climate change added additional warming to the picture (approximately 1.5°C since 1960), the event would have been severe even without the climate change signal." 

Clearly this claim does not dispute or correct the findings of Philip et al 2022 by saying that the weather event itself was "bad luck." In point of fact McKinnon and Simpson were answering a question that Philip et al 2022 explicitly said their analysis couldn't answer. They found that the conditions that caused the event can be reproduced in climate models, and it would have been severe without AGW, but AGW still added about 1.5°C to the severity of the event (relative to 1960 conditions). Note that this analysis essentially splits the difference between Philip and Bercos-Hickey, but relative to 1960 conditions, rather than preindustrial conditions. So this analysis puts the anthropogenic contribution to extreme temperatures more in line with Philip.

Update, 8/10/2025: I just saw a LinkedIn post from Karen McKinnon confirming my take on the DOE's treatment of her paper (I'm sure she hasn't read my post). She posted a couple days ago, 

The authors of the DOE study, however, only included the following quote from our study: “the most likely explanation remains that the weather event itself was ‘bad luck.’” When taken out of context, this quote fails to reflect the reality, which is that the weather event occurred against a warmer baseline, leading to a hotter and longer heatwave.

One has to wonder why, if I was able to understand the meaning of her paper, the combined efforts of the five authors of the DOE report couldn't get it right.  

Study 3 - The 2023 Oregon Climate Assessment (OCA)[4]

"The 2023 Oregon Climate Assessment (Fleischman, 2023) concluded that the heat dome would have formed even without climate change and 'There is no evidence that the highly unusual combination of weather features that drove the heat dome were made more likely by climate change, and climate models do not project an increase in the frequency of high-pressure ridges over the Pacific Northwest' (Fleischman, 2023, p. 49)."

Even aside from misspelling Erica Fleishman as "Fleischman" twice, there are several problems with this quote. The quote from the study is technically true but also extremely misleading. Here's the paragraph from 2023 Oregon climate assessment where this quote was taken. The emphasis below is mine:

The simplest and most straightforward way to interpret the effect of anthropogenic climate change on the severity of the June 2021 event is to assume that it elevated temperatures by an amount equivalent to the mean increase in temperature since anthropogenic climate change began. A recent study estimated that this heat wave was about two degrees Fahrenheit warmer than it would have been without human influence on the climate (Bercos-Hickey et al. 2022), consistent with the increase in mean temperature. An event of this magnitude is likely to occur once in 1000 to 100,000 years (McKinnon and Simpson 2022, Thompson et al. 2022). A heat dome would have occurred without climate change, but maximum temperatures would not have been as high (McKinnon and Simpson 2022). Thompson et al. (2022) estimated that a heat wave of similar magnitude will recur about once in six years by the end of the twenty-first century if concentrations of greenhouse gases do not decrease. There is no evidence that the highly unusual combination of weather features that drove the heat dome were made more likely by climate change, and climate models do not project an increase in the frequency of high-pressure ridges over the Pacific Northwest (Loikith et al. 2022). However, the relations between extreme atmospheric circulation patterns and climate change are not yet fully understood.

This summary clearly articulates what appears to have emerged from attribution studies for the WNA heat dome since the publication of Philip et al 2022. The 2023 OCA report follows both Bercos-Hickey and Thompson et al 2022[5] to estimate the anthropogenic signal to be 2°F. But there's a clear distinction being made here about the likelihood of 1) the combination of weather features that formed the WNA heat dome and 2) how warm that heat dome became. According to this OCA report, the unusual combination of weather features was not made more likely by AGW, but AGW did make the event ~2°F hotter, and they argued that events of this magnitude would increase in frequency from once in 1000 years (or longer) to once in 6 years by 2100, following Thompson et al 2022[5]. That study projects that the PNW heat dome increases in frequency to anywhere from a 0.5% chance (under SSP2-4.5) to a 17% chance (under SSP5-8.5) by 2100. 

Fig 2 from Thompson et al 2022

So predictably the DOE report does not cite Thompson et al, even though it was cited in the paragraph the DOE quoted from. Worse, they presumably read the whole paragraph in the OCA report, but they chose to quote only the select portions that they could use to support the DOE narrative.

Conclusion

So to varying degrees the DOE report mishandled three studies in one paragraph. As a rapid attribution analysis, Philip et al 2022 predictably was improved by later analysis, and this later analysis showed weaknesses in GEV analysis that Philip et al acknowledged. These later studies still provided further analysis that both revised and reinforced the general conclusions of the original study, namely that the WNA heat dome:

• Was extremely rare with or without AGW given current conditions, and it is estimated to be anywhere from a 1-in-1000 event (0.1%) to 1-in-100,000 event (0.001%)
• The weather conditions that formed the heat dome would have happened with or without AGW.
• The event was made significantly hotter because of AGW. The initial estimate of "about 2°C" was revised downward to either ~1°C or ~1.5°C, depending on the paper.
• Events like the NWA heat dome will become more likely as a result of AGW. Taking this event as a 1-in-1000 event now (0.1%), the frequency of this type of event is likely to increase to anywhere from 0.5% (5x more likely) to 17% (170x more likely) during the 21st century with future warming.

When the DOE announced the publication of this report, the DOE advertised it as: "The U.S. Department of Energy today released a new report evaluating existing peer-reviewed literature and government data on climate impacts of Greenhouse Gas Emissions and providing a critical assessment of the conventional narrative on climate change." But at least with the WNA heat dome, this "evaluation" of the peer-reviewed literature reads more like a mishandling of the peer-reviewed literature using highly selective quotations and misrepresenting conclusions from the peer-reviewed literature. The DOE report instead appears designed to support a contrarian narrative on climate change. Roger Pielke Jr referred to it as a "red team" report, and I agree. This section shows itself to be a partisan report designed to support the goals of the current DOE, not advance our understanding of climate change. And while my evaluation here is of essentially just a single section of the report, there are scientists coming out of the woodworks claiming their research has been misrepresented as well. Even Richard Tol, an economist who has been critical of AGW, has acknowledged that of the three times he was cited in this report, the DOE misrepresented him every single time. I document several scientists pointing out how the DOE misrepresented their work in my initial response.

The "Climate Working Group" was given a golden opportunity here. If the vanishingly small number of climate scientists that still support the contrarian narrative had accumulated a wealth of research that supports their position against the overwhelming consensus seen in the scientific literature and virtually every scientific organization on the planet, this was their time to shine. They could have prepared a report that finally vindicated their position against the "conventional narrative on climate change." That didn't happen. Instead, we got a "red team" report that simply repeats the same kinds of debunked contrarian talking points that have been floating around the blogosphere for decades, combined with some pretty shoddy scholarship.

References:

[1] Philip, S. Y., Kew, S. F., van Oldenborgh, G. J., Anslow, F. S., Seneviratne, S. I., Vautard, R., Coumou, D., Ebi, K. L., Arrighi, J., Singh, R., van Aalst, M., Pereira Marghidan, C., Wehner, M., Yang, W., Li, S., Schumacher, D. L., Hauser, M., Bonnet, R., Luu, L. N., Lehner, F., Gillett, N., Tradowsky, J. S., Vecchi, G. A., Rodell, C., Stull, R. B., Howard, R., and Otto, F. E. L.: Rapid attribution analysis of the extraordinary heat wave on the Pacific coast of the US and Canada in June 2021, Earth Syst. Dynam., 13, 1689–1713, https://doi.org/10.5194/esd-13-1689-2022, 2022.
The initial WWA assessment is here: https://www.worldweatherattribution.org/western-north-american-extreme-heat-virtually-impossible-without-human-caused-climate-change/

[2] Bercos-Hickey, E., O’Brien, T. A., Wehner, M. F., Zhang, L., Patricola, C. M., Huang, H., & Risser, M. D. (2022). Anthropogenic contributions to the 2021 Pacific Northwest heatwave. Geophysical Research Letters, 49, e2022GL099396. https://doi.org/10.1029/2022GL099396

[3] McKinnon, K. A., & Simpson, I. R. (2022). How unexpected was the 2021 Pacific Northwest heatwave? Geophysical Research Letters, 49, e2022GL100380. https://doi.org/10.1029/2022GL100380

[4] Fleishman, Erica, and Oregon Climate Change Research Institute. Sixth Oregon Climate Assessment. : Corvallis, Oregon : Oregon Climate Change Research Institute, Oregon State University, 2023. https://ir.library.oregonstate.edu/concern/technical_reports/gt54kw197

[5] Vikki Thompson et al. ,The 2021 western North America heat wave among the most extreme events ever recorded globally. Sci. Adv.8, eabm6860 (2022). DOI:10.1126/sciadv.abm6860