Assessing ExxonMobil’s global warming projections
Insider knowledge
For decades, some members of the fossil fuel industry tried to convince the public that a causative link between fossil fuel use and climate warming could not be made because the models used to project warming were too uncertain. Supran et al. show that one of those fossil fuel companies, ExxonMobil, had their own internal models that projected warming trajectories consistent with those forecast by the independent academic and government models. What they understood about climate models thus contradicted what they led the public to believe.
Structured Abstract
BACKGROUND
In 2015, investigative journalists discovered internal company memos indicating that Exxon oil company has known since the late 1970s that its fossil fuel products could lead to global warming with “dramatic environmental effects before the year 2050.” Additional documents then emerged showing that the US oil and gas industry’s largest trade association had likewise known since at least the 1950s, as had the coal industry since at least the 1960s, and electric utilities, Total oil company, and GM and Ford motor companies since at least the 1970s. Scholars and journalists have analyzed the texts contained in these documents, providing qualitative accounts of fossil fuel interests’ knowledge of climate science and its implications. In 2017, for instance, we demonstrated that Exxon’s internal documents, as well as peer-reviewed studies published by Exxon and ExxonMobil Corp scientists, overwhelmingly acknowledged that climate change is real and human-caused. By contrast, the majority of Mobil and ExxonMobil Corp’s public communications promoted doubt on the matter.
ADVANCES
Many of the uncovered fossil fuel industry documents include explicit projections of the amount of warming expected to occur over time in response to rising atmospheric greenhouse gas concentrations. Yet, these numerical and graphical data have received little attention. Indeed, no one has systematically reviewed climate modeling projections by any fossil fuel interest. What exactly did oil and gas companies know, and how accurate did their knowledge prove to be? Here, we address these questions by reporting and analyzing all known global warming projections documented by—and in many cases modeled by—Exxon and ExxonMobil Corp scientists between 1977 and 2003.
Our results show that in private and academic circles since the late 1970s and early 1980s, ExxonMobil predicted global warming correctly and skillfully. Using established statistical techniques, we find that 63 to 83% of the climate projections reported by ExxonMobil scientists were accurate in predicting subsequent global warming. ExxonMobil’s average projected warming was 0.20° ± 0.04°C per decade, which is, within uncertainty, the same as that of independent academic and government projections published between 1970 and 2007. The average “skill score” and level of uncertainty of ExxonMobil’s climate models (67 to 75% and ±21%, respectively) were also similar to those of the independent models.
Moreover, we show that ExxonMobil scientists correctly dismissed the possibility of a coming ice age in favor of a “carbon dioxide induced ‘super-interglacial’”; accurately predicted that human-caused global warming would first be detectable in the year 2000 ± 5; and reasonably estimated how much CO2 would lead to dangerous warming.
OUTLOOK
Today, dozens of cities, counties, and states are suing oil and gas companies for their “longstanding internal scientific knowledge of the causes and consequences of climate change and public deception campaigns.” The European Parliament and the US Congress have held hearings, US President Joe Biden has committed to holding fossil fuel companies accountable, and a grassroots social movement has arisen under the moniker #ExxonKnew.
Our findings demonstrate that ExxonMobil didn’t just know “something” about global warming decades ago—they knew as much as academic and government scientists knew. But whereas those scientists worked to communicate what they knew, ExxonMobil worked to deny it—including overemphasizing uncertainties, denigrating climate models, mythologizing global cooling, feigning ignorance about the discernibility of human-caused warming, and staying silent about the possibility of stranded fossil fuel assets in a carbon-constrained world.
Historically observed temperature change (red) and atmospheric carbon dioxide concentration (blue) over time, compared against global warming projections reported by ExxonMobil scientists.
(A) “Proprietary” 1982 Exxon-modeled projections.
(B) Summary of projections in seven internal company memos and five peer-reviewed publications between 1977 and 2003 (gray lines).
(C) A 1977 internally reported graph of the global warming “effect of CO2 on an interglacial scale.”
(A) and (B) display averaged historical temperature observations, whereas the historical temperature record in (C) is a smoothed Earth system model simulation of the last 150,000 years.
Abstract
Climate projections by the fossil fuel industry have never been assessed. On the basis of company records, we quantitatively evaluated all available global warming projections documented by—and in many cases modeled by—Exxon and ExxonMobil Corp scientists between 1977 and 2003. We find that most of their projections accurately forecast warming that is consistent with subsequent observations. Their projections were also consistent with, and at least as skillful as, those of independent academic and government models. Exxon and ExxonMobil Corp also correctly rejected the prospect of a coming ice age, accurately predicted when human-caused global warming would first be detected, and reasonably estimated the “carbon budget” for holding warming below 2°C. On each of these points, however, the company’s public statements about climate science contradicted its own scientific data.
In 2015, investigative journalists uncovered internal company documents showing that Exxon scientists have been warning their executives about “potentially catastrophic” anthropogenic (human-caused) global warming since at least 1977. Researchers and journalists have subsequently unearthed additional documents showing that the US oil and gas industry writ large—by way of its trade association, the American Petroleum Institute—has been aware of potential human-caused global warming since at least the 1950s; the coal industry since at least the 1960s (4); electric utilities, Total oil company, and General Motors and Ford motor companies since at least the 1970s; and Shell oil company since at least the 1980s.
This corpus of fossil fuel documents has attracted widespread scholarly, journalistic, political, and legal attention, leading to the conclusion that the fossil fuel industry has known for decades that their products could cause dangerous global warming. In 2017, we used content analysis to demonstrate that Exxon’s internal documents, as well as peer-reviewed studies authored or coauthored by Exxon and ExxonMobil Corp scientists, overwhelmingly acknowledged that global warming is real and human-caused.
By contrast, we found that the majority of Mobil and ExxonMobil Corp’s public communications promoted doubt on the matter. Cities, counties, and states have accordingly filed dozens of lawsuits variously accusing ExxonMobil Corp and other companies of deceit and responsibility for climate damages. The attorney general of Massachusetts, for instance, alleges that ExxonMobil has had a “long-standing internal scientific knowledge of the causes and consequences of climate change” and waged “public deception campaigns” that misrepresented that knowledge. Civil society campaigns seeking to hold fossil fuel interests accountable for allegedly misleading shareholders, customers, and the public about climate science have emerged under monikers such as #ExxonKnew, #ShellKnew, and #TotalKnew.
But what exactly did the fossil fuel industry understand about the role of fossil fuels in causing global warming, and how accurate did their understanding prove to be? Several of the documents in question include explicit projections of the amount of warming that could be expected to occur over time in response to rising atmospheric greenhouse gas concentrations. Yet, whereas the text of these documents has been interrogated in detail, the numerical and graphical data in them have not. Indeed, no one has systematically reported climate modeling projections by any fossil fuel interest, let alone assessed their accuracy and skill. This contrasts with academic climate models, whose performance has been extensively scrutinized.
The fuckers knew - the Dirty Fuels Cartel knew what was coming because of what they were doing.
They fucking knew.
And we've seen numerous studies of numerous smoking guns now. Class action lawsuits should be pouring in, and I should think the insurance companies would be leading the charge.
