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Exxon knew about global warming

Exxon knew about global warming from climate projections made by its researchers between 1977 and 2003.

These projections accurately predicted subsequent global warming, reveals a Harvard University study. However, the US oil giant’s public statements contradict its own scientific data.

It is known that “exxon knew” half a century ago the threats of global warming (there are even several initiatives to denounce and investigate it), but now scientists from Harvard University (USA) and the Potsdam Institute for Climate Impact Research (Germany) put numbers to that statement .

In this first systematic assessment of the fossil fuel industry’s climate projections, they confirm what ExxonMobil – one of the world’s largest oil and gas companies – has known since the 1970s: that burning fossil fuels would cause global warming. global rate of about 0.20 °C per decade.

Global warming projections

The findings, published in the journal Science and synthesized in a graph with all the global warming projections released by researchers from the North American oil company between 1977 and 2003, they are based on statistical analysis of data never before revealed and hidden in the company’s own documents, as well as in scientific articles. of that time and later years.

Exxon, global warming, pollution, gas, gases, fossil fuels
Global warming projections reported by ExxonMobil scientists in internal documents and scientific publications between 1977 and 2003 (black and gray lines), superimposed on historically observed temperature changes (red). / G. Supran et al./Science

incredible precision

Diving into Exxon’s data, the study reveals that the company knew about the coming warming with astonishing accuracy. “Most of his predictions were consistent with observations made after”, indicates the work, “and their projections were also consistent with those of independent academic and government models, or at least as accurate as these.”, despite the efforts of the oil company to sow uncertainties and doubts.

Using statistical techniques established by the Intergovernmental Panel on Climate Change (IPCC), the study concludes that between 63% and 83% of global warming projections reported by ExxonMobil scientists matched later observed temperatures. Furthermore, they had askill score” average of 72%.

For comparison, the warming predictions of James Hansen, the NASA scientist who presented them to the US Congress in 1988, had scores ranging from 38% to 66%.

The study concludes that ExxonMobil “It 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’ to keep warming below 2°C.”. At each of these points, however,the company’s public statements about climate science contradict its own scientific data”.

Exxon knew, but did he lie?

As historians of science, we don’t use the word “lie” lightly, because it implies intent, which is difficult to prove, and it suggests that the company never accurately represented reality, which is not exactly the case.,” explains lead author Geoffrey Supran, an associate professor at Harvard University and the University of Miami as of this year.

What is certain is that the company ‘fooled’ the public and policy makers about climate science and its implications –underlined–. On this point, we are very explicit in our conclusions: The company has contributed precision, skill and discretion to climate science, while proclaiming doubts about that science.”.

Although the professor clarifies that this does not mean that ExxonMobil and other oil and gas companies have not explicitly lied on other occasions about climate change: “They have. As Naomi Oreskes and I reported in the Boston Globe, CEOs have lied under oath to the US Congress about their record of public communications on climate change.”

The nail in the coffin of the oil company’s claims

The authors note that their findings “corroborate and add quantitative precision to the claims of academics, journalists, lawyers, politicians and others that ExxonMobil accurately anticipated the threat of man-made global warming, prior to and in parallel with orchestrating lobbying and propaganda campaigns to delay the climate action and refute claims by Exxon and its supporters that those claims were incorrect”.

This is the nail in the coffin for ExxonMobil’s claims that they were falsely accused of weather irregularities.”, comments Supran, “our analysis shows that their own data contradict their public statements, which included exaggerated uncertainties, criticizing climate models, mythologizing global cooling and feigning ignorance about when – or if – man-made global warming would be measurable, all while remaining silent about the threat from fossil fuel assets”.

The professor did not communicate his results to ExxonMobil because “it is not an academic practice to ask for your comments, as it happens in journalism” and reiterates that this work can help to inform the “increasing number of initiatives –including litigation, political investigations and grassroots activism– demanding that the oil and gas industry be held accountable for its history of fraud and climate damage”.


G. Supran et al. “Evaluating ExxonMobil’s Global Warming Projections”. Science2023


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