# Exxon understood the reality of human-caused climate change decades ago, then spent years publicly manufacturing doubt about it

**Verdict: Proven.** Two things are documented, and together they are the case. First, Exxon's own scientists understood by the late 1970s and early 1980s that burning fossil fuels was warming the planet, and their in-house projections of that warming turned out to be accurate: a 2023 peer-reviewed analysis in Science found Exxon's 1977–2003 modeling forecast roughly 0.20 degrees Celsius of warming per decade, on par with independent academic and government models and with what has since been observed. Second, a 2017 study in Environmental Research Letters showed that while Exxon's internal and peer-reviewed documents acknowledged the science, its paid newspaper 'advertorials' overwhelmingly expressed doubt about it. The internal knowledge and the public doubt-casting are both established in the record. What is not settled here, and is deliberately kept separate, is the outcome of specific lawsuits: some, like New York's 2019 securities-fraud case, Exxon won outright, while others brought by states and cities remain in progress. Rated substantiated for the documented conduct, with the contested legal claims attributed to the plaintiffs who make them.

Category: Science, Space & Technology · Era: 1970s–2020s · First circulated: The internal knowledge dates to 1977–1986; the documented public account broke in 2015, when InsideClimate News published 'Exxon: The Road Not Taken' and the Los Angeles Times ran its 'What Exxon Knew' series with Columbia's Graduate School of Journalism · Believed by: Broadly accepted as established by climate scientists, historians of science, investigative journalists, and a wave of state and municipal litigators; disputed chiefly by ExxonMobil itself and allied commentators, who contest the framing and the legal conclusions rather than the underlying documents
URL: https://theconspiratory.com/theory/exxon-climate-denial

## Summary
In 2015 two investigations, one by InsideClimate News and one by the Los Angeles Times with Columbia University, revealed that Exxon had run a serious in-house climate research program from the late 1970s and understood early that fossil fuels were warming the planet, then pivoted toward casting public doubt on the very science its scientists had confirmed. Peer-reviewed work later hardened the case: a 2017 study documented the gap between what Exxon said internally and the doubt it sold in paid newspaper advertisements, and a 2023 study in Science showed that Exxon's own global-warming projections had been strikingly accurate all along. This case file separates what the documents establish, the internal knowledge and the public doubt-casting, from the parts that are still being fought in court. The former is substantiated. The specific legal claims in ongoing lawsuits are attributed to the attorneys general and municipalities pressing them, not asserted here as settled fact.

## The claim
That Exxon (and later ExxonMobil) knew from its own scientists, as early as the late 1970s and 1980s, that carbon dioxide from burning fossil fuels was warming the planet and posed grave risks; that its in-house projections of that warming were accurate; that the company nonetheless spent the following decades publicly manufacturing doubt about climate science through paid 'advertorials' and the funding of denial and lobbying groups such as the Global Climate Coalition; and that this contradiction between private knowledge and public messaging is documented in the company's own records and in peer-reviewed analysis.

## Origin and timeline
- 1977: Exxon senior scientist James Black tells the company's management committee that there is broad scientific agreement that the most likely way humanity is influencing global climate is through carbon dioxide released by burning fossil fuels. A year later he warns that doubling atmospheric CO2 would raise average global temperatures by roughly two to three degrees Celsius.
- 1979–1982: Exxon launches an ambitious internal research program, including CO2 sampling instruments aboard its supertanker the Esso Atlantic and rigorous climate modeling. Company scientists assemble a body of work confirming that fossil-fuel combustion is driving measurable warming and estimating its likely pace.
- 1982: An internal Exxon primer summarizes the state of the science for management, projecting warming broadly consistent with the outside scientific consensus and noting potentially serious consequences. The document is marked not for public distribution.
- Late 1980s: Exxon winds down its in-house CO2 research. As climate change gains political salience after NASA scientist James Hansen's 1988 congressional testimony, the company shifts posture from studying the problem to contesting it publicly.
- 1989: Exxon becomes a founding member of the Global Climate Coalition, an industry group that spent the following decade emphasizing scientific uncertainty and lobbying against measures such as the Kyoto Protocol. The company also begins funding an array of think tanks and advocacy groups that dispute mainstream climate science.
- 1989–2004: ExxonMobil runs paid, editorial-style 'advertorials' in The New York Times. A later content analysis finds that these overwhelmingly expressed doubt about whether climate change was real, human-caused, serious, and solvable, in contrast to the company's own internal and peer-reviewed documents.
- 2015: InsideClimate News publishes 'Exxon: The Road Not Taken', and the Los Angeles Times runs 'What Exxon Knew' with Columbia University's Graduate School of Journalism. Built on internal documents and interviews with former employees, the investigations establish the gap between Exxon's early knowledge and its later public messaging, and the phrase 'Exxon Knew' enters wide circulation.
- 2017: Geoffrey Supran and Naomi Oreskes of Harvard publish a peer-reviewed content analysis in Environmental Research Letters comparing 187 Exxon climate communications, concluding that the company's advertorials misled the public even as its internal and academic documents acknowledged the science.
- 2023: Supran, Stefan Rahmstorf, and Oreskes publish in Science a quantitative assessment finding that global-warming projections modeled by Exxon and ExxonMobil scientists from 1977 to 2003 were accurate and skillful, forecasting about 0.20 degrees Celsius of warming per decade, consistent with subsequent observations.

## The evidence, claim by claim
- Claim: Exxon's own scientists told the company decades ago that fossil fuels were warming the planet.
  Evidence: Documented in Exxon's internal records. In 1977 senior scientist James Black briefed the management committee that burning fossil fuels was the most likely driver of climate change, and in 1978 he estimated that doubling CO2 would warm the planet by roughly two to three degrees Celsius, a figure close to the modern consensus. Internal memos and a 1982 primer reviewed by InsideClimate News and the Los Angeles Times show the company's technical staff treating human-caused warming as real and consequential well before it was a public controversy.
- Claim: Exxon's in-house climate projections were not just present but accurate.
  Evidence: Confirmed by peer-reviewed analysis. The 2023 Science paper by Supran, Rahmstorf, and Oreskes evaluated the warming projections that Exxon and ExxonMobil scientists produced and modeled between 1977 and 2003. It found most of them accurately forecast warming of about 0.20 degrees Celsius per decade, matching later observations, and that their models were at least as skillful as contemporaneous academic and government models. The company's scientists also correctly rejected a coming ice age and reasonably estimated the carbon budget for limiting warming to two degrees.
- Claim: The company publicly cast doubt on the very science it privately accepted.
  Evidence: This is the crux, and it is documented in the 2017 Environmental Research Letters study. Supran and Oreskes analyzed 187 climate communications and found a systematic split: Exxon's internal reports and peer-reviewed papers largely acknowledged that climate change was real and human-caused, while its paid advertorials in The New York Times, running from 1989 to 2004, overwhelmingly emphasized doubt and uncertainty. A 2020 addendum, drawing on additional documents, reinforced the finding. The discrepancy between private knowledge and public messaging is the substantiated core of 'Exxon Knew'.
- Claim: Exxon funded organized efforts to manufacture doubt about climate science.
  Evidence: Established through funding records and reporting. Exxon was a founding member of the Global Climate Coalition, an industry group that stressed scientific uncertainty and campaigned against climate agreements through the 1990s. Analyses by groups including the Union of Concerned Scientists and Greenpeace document tens of millions of dollars Exxon channeled over the years to think tanks and advocacy organizations that disputed mainstream climate science. The company later said it had ended funding to some such groups, but the historical pattern is well recorded.
- Claim: The courts have already found Exxon guilty of climate fraud.
  Evidence: Not established, and this is where the legal picture must be kept separate from the documented conduct. New York's attorney general sued Exxon for allegedly misleading investors about climate risk, and in December 2019 Justice Barry Ostrager of the New York Supreme Court ruled for Exxon, finding the state had not proven material misrepresentation. Other suits, including Massachusetts Attorney General Maura Healey's consumer- and investor-protection case and actions by cities and states, remain in progress. Those cases advance allegations that courts have not resolved; the 'Exxon Knew' finding this file rates as substantiated rests on the documents and peer-reviewed studies, not on any lawsuit's outcome.

## Why people believe it
- The core is documented in Exxon's own files. Internal briefings, a 1982 primer, and the company's tanker-based CO2 research are not inference but paper trail, and a paper trail written by the company itself is very hard to dismiss.
- It matches a template the public already recognizes. The tobacco industry demonstrably funded science to obscure the harms of smoking, so an oil-industry version of manufactured doubt sounds not merely plausible but familiar, which primes people to accept the fullest version quickly.
- The peer-reviewed follow-up gave the story unusual weight. It is one thing for journalists to report that Exxon knew; it is another for a study in Science to show the company's own projections were accurate, and that scientific confirmation lifted the case above ordinary corporate scandal.
- The contrast is stark and morally legible. A company that understood an existential risk to its own business and chose to sow public doubt anyway offers a clear story of knowledge versus responsibility, and stories with that shape travel far.

## Open questions
- How much Exxon's doubt-casting actually delayed climate policy is genuinely hard to isolate. The advertorials and denial funding are documented, but quantifying their causal effect on public opinion or on specific legislation is a separate and unresolved question from the fact that the messaging happened.
- The legal exposure is unsettled. Exxon won New York's 2019 securities-fraud case outright, while suits by Massachusetts and various municipalities continue. Whether the documented conduct amounts to actionable fraud or consumer deception is a question for courts that have so far reached different results, and this file does not prejudge them.
- Exxon disputes the framing rather than the documents. The company argues its statements have been quoted selectively and its research mischaracterized, and it published a formal comment challenging the 2017 study. The underlying records are not in serious doubt, but the interpretation continues to be contested by the company itself.

## Sources
- Exxon: The Road Not Taken, InsideClimate News (2015): https://insideclimatenews.org/project/exxon-the-road-not-taken/
- Exxon's Own Research Confirmed Fossil Fuels' Role in Global Warming Decades Ago, Neela Banerjee, Lisa Song and David Hasemyer, InsideClimate News (2015): https://insideclimatenews.org/news/16092015/exxons-own-research-confirmed-fossil-fuels-role-in-global-warming/
- Assessing ExxonMobil's climate change communications (1977–2014), Geoffrey Supran and Naomi Oreskes, Environmental Research Letters (2017): https://iopscience.iop.org/article/10.1088/1748-9326/aa815f
- Assessing ExxonMobil's global warming projections, G. Supran, S. Rahmstorf and N. Oreskes, Science (2023): https://www.science.org/doi/10.1126/science.abk0063
- What Exxon Knew, Columbia Magazine, Columbia University (2016): https://magazine.columbia.edu/article/what-exxon-knew
- ExxonMobil climate change denial, Wikipedia: https://en.wikipedia.org/wiki/ExxonMobil_climate_change_denial
- Exxon Knew about Climate Change Almost 40 Years Ago, Shannon Hall, Scientific American (2015): https://www.scientificamerican.com/article/exxon-knew-about-climate-change-almost-40-years-ago/
- Exxon Wins New York Climate Change Fraud Case, Jeff Brady, NPR (2019): https://www.npr.org/2019/12/10/780317799/exxon-wins-new-york-climate-change-case
- Exxon's Climate Denial History: A Timeline, Greenpeace USA: https://www.greenpeace.org/usa/climate/exxons-climate-denial-history-a-timeline/

Rated by The Conspiratory, a neutral, sourced encyclopedia of conspiracy theories. Full page: https://theconspiratory.com/theory/exxon-climate-denial