Jan 12, 2023 - Science

Exxon's climate research accurately projected global warming, study finds

<span style="background:#ffa515; padding:3px 5px;color:white;">Historical</span> and <span style="background:#898989; padding:3px 5px;color:white;">Exxon-projected</span>  global warming scenarios
Data: Supran et al. Science 2023; Chart: Axios Visuals

ExxonMobil's own climate science research, which began in the 1970s, accurately predicted the pace and severity of global warming, a new study finds.

Why it matters: The study is the first to examine the performance of Exxon's internal climate modeling as well as its scientists' collaborations with outside researchers. It provides a quantitative assessment of how much the company's executives may have known about the risks of burning oil and gas and when.

  • The study provides more evidence that Exxon's communication to investors and the public through the 21st century, which has played down the threats posed by climate change and cast computer models as uncertain, did not match what executives were told internally.
  • The research, dismissed by Exxon, may play a role in ongoing legal action against the company for allegedly misleading investors and the public about the dangers of global warming.

The big picture: Exxon scientists have been at the forefront of climate change research using computer models, the study published in the journal Science shows. According to the study, between 63% and 83% of the climate projections reported by Exxon scientists were accurate in predicting subsequent global warming.

  • The Exxon scientists' projections showed the world would warm at a rate of about 0.20°C per decade, which was in line with independent academic and government studies in the 1970s through the early 2000s.
  • According to the study, Exxon's research also led to an accurate estimate of how much carbon dioxide could be emitted before the world would warm by more than 2°C.
  • This implied that some of the company's oil and gas holdings could become stranded assets, but such risks were not communicated to the company's investors or the public, the study notes.

Of note: The study assessed the skill scores of projections from Exxon's in-house climate modeling were more accurate than what then-NASA scientist James Hansen famously provided to Congress in his 1988 testimony warning human-caused global warming had started.

How they did it: The study examined 32 internal documents containing scientific research produced by in-house Exxon scientists between 1977 and 2002, and 72 peer-reviewed studies authored or co-authored by company scientists between 1982 and 2014.

  • The internal documents had previously been analyzed for their text as part of a series of investigative journalism projects that have come to be known as #ExxonKnew, but the recent work breaks new ground by assessing the accuracy of modeling projections shown in these papers.
  • To analyze Exxon scientists' predictions, the researchers took every global warming projection they could find, extracted and digitized the graphs, and quantitatively tested the predictions using established methods.

The intrigue: The new study involves researchers Naomi Oreskes and Geoffrey Supran, who have published multiple studies that qualitatively examined what Exxon knew internally and told the public about climate change.

  • Both researchers have been vocal critics of Exxon's criticism of climate science as uncertain and unreliable, having extensively researched the company's public-facing advertisements and statements on the issue.
  • Another coauthor is Stefan Rahmstorf, a well-known climate scientist and director of the Potsdam Institute for Climate Impact Research in Germany.

What they're saying: "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," the study states.

  • "We now have airtight, unimpeachable evidence that ExxonMobil accurately predicted global warming years before it turned around and publicly attacked climate science and scientists," said lead author Geoffrey Supran of the University of Miami, via email.
  • "In essence, Exxon didn’t just know, they knew precisely," said Supran, who is starting the Climate Accountability Lab at the University of Miami, which "Will investigate climate disinformation & propaganda by fossil fuel interests," he stated via Twitter.

The other side: Exxon dismissed the study's findings while touting its climate research in a statement to Axios.

  • "This issue has come up several times in recent years and, in each case, our answer is the same: those who talk about how 'Exxon Knew' are wrong in their conclusions," said Exxon spokesperson Todd Spitler.
  • "Some have sought to misrepresent facts and ExxonMobil’s position on climate science, and its support for effective policy solutions, by recasting well intended, internal policy debates as an attempted company disinformation campaign," he said.
  • "ExxonMobil’s understanding of climate science has developed along with that of the broader scientific community," he said.
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