New study sheds light on what Exxon 'knew' decades ago about climate science

New study sheds light on what Exxon ‘knew’ decades ago about climate science

Summary of all global warming projections reported by ExxonMobil scientists in internal documents and peer-reviewed publications between 1977 and 2003 (gray lines), overlaid on historically observed temperature changes (red). Solid gray lines indicate global warming projections modeled by ExxonMobil scientists themselves; dashed gray lines indicate projections reproduced internally by ExxonMobil scientists from third-party sources. Shades of gray with model start dates, from earliest (1977: lightest) to most recent (2003: darkest). Credit: Geoffrey Supran

Climate projections reported by ExxonMobil scientists between 1977 and 2003 were accurate and adept at predicting subsequent global warming and contradicted the company’s public claims, a new Harvard study shows.


In the first systematic assessment of the fossil fuel industry’s climate projections, researchers from Harvard University and the Potsdam Institute for Climate Impact Research put to rest what Exxon “knew” decades ago about climate science: that burning fossil fuels would leads to 0.20. ± 0.04 degrees Celsius of global warming per decade.

The findings, published in the peer-reviewed journal Science and summarized in a single graph showing every global warming projection reported by Exxon and ExxonMobil Corp scientists between 1977 and 2003, are based on statistical analyzes of previously unreported data buried in the company’s own documents.

Although it has been widely reported that Exxon knew about the threat of global warming as early as the 1970s, this study is the first quantitative review of the company’s early climate science. Previous research has focused on Exxon’s inconsistent internal and external rhetoric on climate change. This report analyzes company data that reveals the company knew how much warming would occur with startling accuracy.

“We find that most of their projections accurately forecast warming consistent with subsequent observations,” the report concludes. “Their projections were also consistent with those of independent academic and government models and at least as proficient.”

Using established IPCC statistical techniques, the study finds that 63-83% of global warming projections reported by ExxonMobil scientists were consistent with subsequently observed temperatures. Moreover, the projections modeled by ExxonMobil scientists had an average “qualification score” of 72 ± 6%, with the highest score being 99%. By comparison, NASA scientist Dr. James Hansen’s global warming predictions presented to the US Congress in 1988 had skill scores ranging from 38% to 66%. (When considering differences between forecast and observed atmospheric CO2 levels, the “qualification score” of projections modeled by ExxonMobil scientists was 75 ± 5%, with seven projections scoring 85% or higher. Again, for comparison, Hansen’s 1988 projections had corresponding skill scores of 28 to 81%).

The study finds that “Exxon and ExxonMobil Corp correctly rejected the prospect of a future ice age, accurately predicted when human-caused global warming would first be detected, and reasonably estimated the ‘carbon budget’ for keeping warming below 2°C. each of these points, however, the company’s public statements about climate science have contradicted its own scientific data.”

The study adds weight to ongoing legal and political investigations into ExxonMobil.

“These findings corroborate and add quantitative precision,” the authors write, “to the claims of scholars, journalists, lawyers, politicians, and others that ExxonMobil accurately predicted the threat of human-caused global warming, both before and in parallel with its orchestration of lobbying and propaganda. campaigns to delay action on climate change and rejects claims by ExxonMobil Corp and its defenders that these claims are incorrect.”

“This is the nail in the coffin of ExxonMobil’s claims that it has been falsely accused of climate misconduct,” commented lead author and Harvard University Research Associate Geoffrey Supran (Supran began as Associate Professor of Environmental Science and Policy at the University ). from the Rosenstiel School of Marine, Atmospheric and Earth Sciences in Miami January 2023). “Our analysis shows that ExxonMobil’s own data contradicted its public statements, which included exaggerating uncertainties, criticizing climate models, mythologizing global cooling, and feigning ignorance about when — or if — human-caused global warming would be measurable, all while remaining silent on the threat of failed fossil fuel assets”.

The paper acknowledgments state that this research was supported by Harvard University Faculty Development Funds and the Rockefeller Family Fund.

More information:
G. Supran, Assessing ExxonMobil’s Global Warming Projections, Science (2023). DOI: 10.1126/science.abk0063. www.science.org/doi/10.1126/science.abk0063

Provided by Harvard University

Citation: New study puts number on what Exxon ‘knew’ decades ago about climate science (2023, January 12) Retrieved January 12, 2023 from https://phys.org/news/2023-01- exxon-knew-decades-climate- science.html

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