ExxonMobil Accurately Projected Rising Temperatures While Publicly Disparaging Climate Science

January 20, 2023 | 10:33 am
Shaina Sadai
Hitz Fellow

New research by Geoffrey Supran, Stefan Rahmstorf, and Naomi Oreskes published in Science looks at the climate projections from ExxonMobil’s internal scientific research and compares them to the observed temperature rise and to previous work analyzing the company’s deceptive statements on climate science. This research, which immediately sparked conversations and renewed calls for corporate accountability, is particularly fascinating because it combines climate modeling, interdisciplinary archival research, and corporate accountability—some of my favorite topics!

To understand what Exxon (which merged with Mobil in 1999 to become ExxonMobil, which I’ll use for simplicity) knew about climate projections, researchers from the physical and social sciences came together to produce interdisciplinary research. They combined their expertise in climate science, science history, and document analysis to create a perfect blend of scientific analysis and socially relevant research.

This methodology is similar to my own work combining climate science, political science, and history to reconstruct how UN climate negotiations have played out and what that implies for climate justice. The present is always being created out of past actions that led to where we are today. As researchers look to apply their skills to the difficult problems of a changing climate, working together to combine expertise in new ways can help inform conversations about how we got here and where we are going.

Let’s dig into what Supran et al.’s new research tells us about the past and how we can apply it to the future by considering five main takeaways from this work:

1) ExxonMobil knew decades ago that its products are harmful

ExxonMobil documents spanning from 1977 to 2003 featured graphs showing how temperatures would rise as a result of the heat-trapping emissions produced from burning the fossil fuels the company extracted, refined, marketed, and sold. In this new study, the authors compared the temperatures ExxonMobil projected to the observed temperatures that actually occurred over the past few decades.

This new research found that ExxonMobil’s climate projections from its internally developed models accurately projected the temperature rise that has happened since then and that its calculations were in line with independent research produced at the time by academic and government scientists.

This graph summarizes the temperature projections from ExxonMobil’s documents (grey and black lines) and compares them to the observed temperature rise (red). The lightest lines are from the earliest projections, the lightest grey being from 1977, and the darker colors are later with the black line being from 2003. (Source: Supran et al., 2023)

2) ExxonMobil produced quality science internally, but cast doubt on it publicly

ExxonMobil was producing quality science. Corporate leadership was informed about advances in climate science and incorporated those advances when its scientists built their own models. Regardless, the company publicly cast doubt on the reality of global warming, attempted to discredit climate scientists and climate models, and tried to block climate action. The new paper in Science summarizes key statements by ExxonMobil executives between 2000 and 2013 that cast doubt on the science. These statements are a striking contrast to the science company employees were producing internally. This contrast is more proof to add to the already strong evidence that ExxonMobil intentionally tried to undermine and discredit climate science. Supran and his colleagues compellingly summarize the research, concluding: “All told, ExxonMobil was aware of contemporary climate science, contributed to that science, and predicted future global warming correctly.”

3) ExxonMobil predicted the possibility of linking rising temperatures to fossil fuels

ExxonMobil researchers accurately predicted when it would become possible to attribute changes in climate to human activity. Their internal research estimated that scientists would be able to link rising temperatures to the burning of fossil fuels sometime between 1995 and 2005. The Intergovernmental Panel on Climate Change’s (IPCC) 2nd Assessment Report, published in 1995, showed that human-caused warming was detectable.

Attribution science has only gotten stronger in recent years. Scientists are now able to attribute not only temperature rise, but also other climate impacts—such as more intense storms, heavy precipitation, wildfires and more—to human activity. And attribution science can go even further, attributing climate impacts not just to human activity, but also to the activities of the fossil fuel industry—including ExxonMobil. Research produced by the Union of Concerned Scientists (UCS) has shown that rising temperatures, sea level rise, and ocean acidification have all been made worse by fossil fuel companies’ activities and products.

4) ExxonMobil calculated constraints on the ‘carbon budget’ if nations addressed global warming

A subset of the ExxonMobil research calculated what the remaining “carbon budget” would be if the international community moved to halt the rising concentrations of heat-trapping gases in the atmosphere. The company’s own research estimated that to prevent the average temperature from rising beyond 2 degrees Centigrade (3.6 degrees Fahrenheit) above preindustrial levels that a carbon budget of 251 to 716 gigatonnes of carbon between 2015 and 2100 would be the limit. The current IPCC estimates now put the budget at 442 to 651 gigatonnes. Such a constraint would clearly place a limit on the amount of fossil fuels ExxonMobil could extract, produce and market.

5) ExxonMobil denigrated climate models, but models produce robust science

Finally, ExxonMobil’s efforts over the past five decades to cast doubt on modeling and the socially relevant science it produces was an intentional misdirection that delayed progress to address climate change. In fact, climate models produce robust science. For decades scientific modeling has been a key tool for projecting future conditions. This research shows yet again that climate modeling is a reliable and powerful tool for understanding our world.

Scientists who build climate models are always trying to improve models and projections, and while the models were already good decades ago, they are even better today. Model results from the latest IPCC report show that the world is increasingly heading into an ever more dangerous situation as temperatures continue to rise, primarily from burning fossil fuels. Policymakers should heed the science and take projections of today’s climate models seriously by doing everything they can to limit global temperature rise. That means intensifying climate action and dramatically curbing the production of heat-trapping emissions by 45 percent before 2030.

The latest IPCC report summarizes climate modeling showing that temperatures will continue to rise this century. The amount that temperatures rise by is dependent on heat-trapping emissions. With unchecked fossil fuel production we follow the extremely dangerous red paths shown here (labeled SSP5-8.5 and SSP3-7.0), but with strong, near-term climate action we can still limit rising temperatures (the blue paths labeled SSP1-1.9 and SSP1-2.6). (Source: IPCC, 2021)

Calls for corporate accountability will grow louder

Thanks to a growing body of research (including a previous paper by Supran and Oreskes) that has dug deep into ExxonMobil’s documents, statements, and advertisements, awareness of the company’s intentional misrepresentation of its products’ impacts has increased in recent years among policymakers, litigators, and the general public.

This heightened awareness has resulted in movements for accountability. An increasing number of lawsuits against ExxonMobil and other fossil fuel companies are proceeding through the courts with broad public support. These lawsuits are informed by research, and Supran et al.’s new study will add to the body of evidence plaintiffs use in these cases. Research into the actions of the fossil fuel industry also informed the recent US House of Representatives Committee on Oversight and Reform’s investigation, which in turn has revealed new evidence of the oil and gas industry’s ongoing deception.

As more and more evidence accumulates showing that ExxonMobil and other major fossil fuel companies had substantial knowledge of the harmful climate effects of their products and yet continued to manufacture doubt about climate science while increasing fossil fuel production and lobbying to block climate action, calls for accountability are bound to grow even louder.