ExxonMobil publicly denied global warming but quietly predicted it

In perhaps the most cynically ironic twist in the field of climate science, new research suggests that ExxonMobil may have had better insight into the looming dangers of global warming than even NASA scientists, but nonetheless pursued a decades-long campaign to discredit climate change research and its connection to the burning of fossil fuels.

Despite its public denials, the oil major worked behind closed doors on a stunningly accurate set of global warming forecasts between 1977 and 2003, according to a study published Thursday in Science.

“Not only did Exxon know about climate science, they helped advance it,” said Geoffrey Supran, lead author of the study and former researcher in Harvard University’s Department of History of Science. “Not only did they vaguely know something about global warming decades ago, they knew as much as independent academics and government scientists did. And they probably knew everything they needed to know.”

Reviewing archived documents and memos, researchers found that scientists at what was then Exxon had completed a set of 16 models that predicted global temperatures would rise by an average of about 0.2 degrees Celsius per decade. Since 1981, the Earth’s average global temperature has risen by about 0.32 degrees (0.18 degrees Celsius) per decade, according to NASA.

Researchers at Harvard and the Potsdam Institute for Climate Impact Research found that most ExxonMobil projections are consistent with later global temperature observations, according to the study. Many of the Exxon projections turned out to be more accurate than those of James Hansen, then director of NASA’s Goddard Institute for Space Studies, who testified before the US Senate in 1988 on the “greenhouse effect.”

The analysis adds to a growing body of evidence that the country’s largest oil producer recognized that burning fossil fuels is warming the earth, though it continued to publicly challenge that notion. The paper also shows for the first time how precise and sophisticated the fossil fuel industry’s own climate research was.

In response to the study, ExxonMobil spokesman Todd Spitler said the company’s understanding of climate science has evolved along with that of the broader scientific community. The energy company, he said, is now actively involved in several efforts to mitigate global warming.

“This issue has come up a number of times over the past several years, and our answer is always the same: Those who claim ‘we knew’ are wrong,” Spitler said in a statement. “Some have attempted to misrepresent facts and ExxonMobil’s position on climate science and its support for effective policy solutions by reframing well-intentioned internal policy debates as the company’s attempted disinformation campaign.”

The Harvard-led study builds on previous academic research, in addition to investigative reports from InsideClimate News and the Los Angeles Times, which uncovered a tranche of internal company memos showing that Exxon officials have known that burning fossil fuels has been going on since the late 1970s years would lead to global warming.

Exxon was a pioneer in climate research in the early 1980s. But their public stance on global warming changed dramatically by 1990.

In an internal draft memo dated August 1988 entitled “The Greenhouse Effect,” a public relations executive explained the scientific consensus on the role of fossil fuels in global warming, but wrote that the company should “emphasise the uncertainty.” According to an archived 1989 presentation by Exxon’s manager of science and policy development, “Data confirms that greenhouse gases are increasing in the atmosphere. Fossil fuels contribute most of the CO2.”

However, in 1999 — the year Exxon and Mobil merged — the company’s CEO, Lee Raymond, said that future climate projections “are based on totally unproven climate models, or more commonly, on pure speculation.”

In 2015, Raymond’s successor, Rex Tillerson, who later served as Secretary of State under President Trump, also questioned climate projections related to the amount of carbon dioxide gas in the atmosphere.

“We don’t really know what the climate impact of 600 parts per million versus 450 parts per million is going to be because the models just aren’t that good,” Tillerson said.

Years earlier, however, Exxon’s own 1982 modeling suggested that 600 ppm CO2 would result in 2.3 degrees (1.3 degrees Celsius) more global warming than 450 ppm.

The analysis also revealed that Exxon scientists had predicted that global warming would first become detectable around the turn of the 21st century. Exxon scientists concluded that this warming trend would make the Earth hotter than at any time in at least 150,000 years, disproving unfounded theories of “global cooling” and an imminent Ice Age.

Despite such findings from their own scientists, company officials have poured millions of dollars into a public relations campaign to cast doubt on the science behind climate change. This campaign included prominent ads in The Washington Post, The Wall Street Journal, and The New York Times.

“They were right in dismissing a possible ice age, in accurately predicting when warming would first be evident, in estimating the carbon budget at 2 degrees — and then the company’s subsequent public statements contradicted its own data on all of those points.” , said Supran, now an associate professor of environmental science and policy at the University of Miami.

It wasn’t until 2007 that ExxonMobil publicly acknowledged that climate change was happening and was being driven largely by the burning of fossil fuels and the spread of heat-trapping CO2.

Prior to the Industrial Revolution, CO2 levels had been constant at about 280 ppm of human civilization for nearly 6,000 years, according to the National Oceanic and Atmospheric Administration. Since then, humanity has released an estimated 1.5 trillion tons of carbon emissions from burning fossil fuels — including gas, coal and methane.

In 2022 — which NOAA now ranks as the sixth warmest year on record — CO2 levels hit 420 parts per million in November, a mark the planet has not seen in millions of years.

Nine of the last 10 years have been the warmest since 1880, according to NOAA. These rising temperatures are fueling extreme weather events around the world, and California and the western US have been at the forefront in recent years.

Despite a recent spate of deadly storms that have battered California since the beginning of the year, the American Southwest is still braving one of its driest stretches in 1,200 years. California is also still recovering from a record-breaking 2020 wildfire season that scorched 4.3 million acres statewide. And as Arctic ice continues to melt, sea-level rise threatens to exacerbate coastal erosion.

Recent findings from ExxonMobil have fueled the #ExxonKnew campaign, an environmental crusade that traces its origins to a 2012 gathering of climate activists and experts in La Jolla. Its supporters have accused ExxonMobil of deliberately misleading the public and causing humanity to lose precious time in the fight to cut carbon emissions. They called for investigations into the company’s statements on climate change and fossil fuels.

During that time, dozens of local and state governments, including several California cities, have filed lawsuits against ExxonMobil and other energy companies for organizing campaigns of public deception despite internal scientific evidence.

In 2019, a New York state judge dismissed the New York Attorney General’s lawsuit against ExxonMobil, which accused the company of defrauding its shareholders by failing to properly consider the risks of climate change.

As ExxonMobil continues to fight similar lawsuits elsewhere, the company’s website is now chock-full of climate-friendly jargon about how it intends to support a “net-zero future” with “low-emission efforts” — a stark departure from its public stance for more than a decade before.

“There’s this kind of gradual evolution away from total denial and toward what we call discourses of delay,” Supran said. “That kind of fits into the present where we have these much more subtle discourses that position fossil fuels as essential to humanity’s future.”