From the 1980s to the mid-2000s, ExxonMobil, an international oil and gas company based in the United States, was a major force in denying the reality of climate change. It opposed efforts to reduce global warming through regulations. For example, ExxonMobil played a key role in stopping the United States from agreeing to the Kyoto Protocol, an international agreement aimed at reducing greenhouse gas emissions. The company funded groups that criticized the Kyoto Protocol and worked to weaken public trust in the scientific agreement that burning fossil fuels causes global warming. Among major oil companies, ExxonMobil was most active in debates about climate change. A 2007 study by the Union of Concerned Scientists found that ExxonMobil used similar methods, groups, and people as the tobacco industry did when it denied the link between smoking and lung cancer.
ExxonMobil supported groups such as the Competitive Enterprise Institute, George C. Marshall Institute, Heartland Institute, the American Legislative Exchange Council, and the International Policy Network. Between 1998 and 2004, the company gave $16 million to organizations that questioned the effects of global warming. From 1989 until April 2010, ExxonMobil and its earlier company, Mobil, regularly paid for advertisements in major newspapers like The New York Times, The Washington Post, and The Wall Street Journal. These ads claimed that the science of climate change was unclear.
A 2011 study by The Carbon Brief found that 9 out of 10 of the most frequent writers who doubted climate change had connections to ExxonMobil. Greenpeace reported that Koch Industries, a separate company, spent more than $50 million over 50 years to spread doubt about climate change.
Since the 1970s, ExxonMobil and its earlier companies conducted research on global warming. In the late 1970s and through the 1980s, ExxonMobil supported internal studies and university research that aligned with growing scientific understanding of climate change. A 2023 review found that the company’s scientists accurately predicted global warming caused by fossil fuels between 1977 and 2003. The study noted that while scientists in universities and government agencies shared their findings with the public, ExxonMobil worked to hide this information.
In April 2014, ExxonMobil released a report that publicly acknowledged the risks of climate change for the first time. The company predicted that a growing global population, rising living standards, and better access to energy would lead to lower greenhouse gas emissions. In 2015, it supported the idea of a carbon tax, a fee on emissions to reduce pollution.
In 2015, the Attorney General of New York began an investigation to determine whether ExxonMobil’s statements to investors matched its long-term scientific research. In October 2018, based on this investigation, the State of New York sued ExxonMobil, claiming the company misled shareholders by downplaying the risks of climate change to its business.
Own research
From the late 1970s through the 1980s, Exxon, one of the earlier companies that became ExxonMobil, was known for its work on climate change research. Exxon supported studies inside the company and with universities, following the same scientific methods being used by the public. It became known for its knowledge about carbon dioxide (CO₂) in the atmosphere. Between the 1970s and 2015, Exxon and ExxonMobil scientists and university partners published many research papers. ExxonMobil provided a list of more than 50 articles from that time.
In July 1977, a senior scientist at Exxon, James Black, told company leaders that scientists generally agreed that burning fossil fuels was the main way humans were affecting global climate change. Between 1979 and 1982, Exxon studied climate change and climate modeling. This included a project to install a laboratory and sensors on its largest supertanker, the Esso Atlantic, to measure how the ocean absorbs CO₂. In 1980, Exxon noted that synthetic fuels release more CO₂ than their petroleum equivalents. Exxon also studied ways to reduce CO₂ emissions if the East Natuna gas field off Indonesia was developed.
In 1981, Exxon focused its research on climate modeling. In 1982, Exxon’s environmental affairs office shared an internal report with company leaders. The report said that climate change could have very harmful effects and that reducing fossil fuel use would be needed to slow future climate change. It also said that some scientists worried that once climate changes were noticeable, they might not be able to be reversed.
In 1992, a senior ice researcher working for Exxon’s Canadian company, Imperial Oil, studied how global warming could affect Exxon’s operations in the Arctic. The report said that exploration costs in the Beaufort Sea might be lower, but rising sea levels and rougher seas could harm the company’s coastal and offshore buildings. Imperial Oil used these predictions to plan its facilities in the Mackenzie River Delta in the Northwest Territories. In 1996, Mobil, another earlier company that became ExxonMobil, studied how climate change could affect the Sable gas field project. An ExxonMobil spokesperson said that considering environmental risks was standard practice when planning major projects and that this did not conflict with the company’s public policy positions.
In 2016, the Center for International Environmental Law, a public interest law firm, claimed that Humble Oil, an earlier company that became ExxonMobil, knew about rising CO₂ levels and the possibility of global warming since 1957. ExxonMobil responded by saying it is not accurate to claim they had clear knowledge about human-caused climate change before scientists worldwide.
In 1989, after a presentation by Exxon’s manager of science and strategy development, Duane LeVine, to the company’s board, which said that introducing policies to fight climate change could lead to strict and costly measures, Exxon changed its public stance on climate change. This change was due to concerns about how climate policies might affect the oil industry.
In the fall of 2015, InsideClimate News published reports based on eight months of research into ExxonMobil’s internal files and interviews with former employees. The reports said that Exxon conducted advanced climate research decades ago but later avoided sharing all its findings and promoted doubt about the scientific agreement on climate change. Exxon responded by saying the claims were based on selected statements from employees and noted that the company continued climate research during the time in question.
Exxon denied claims that it reduced carbon dioxide research to focus on climate denial. It said falling oil prices in the 1980s hurt oil companies and led to research cuts. Exxon also said it was unclear if greenhouse gas emissions caused significant warming or if immediate action on climate change was needed.
A study by Harvard University researchers Geoffrey Supran and Naomi Oreskes analyzed ExxonMobil’s and its earlier companies’ internal reports, peer-reviewed papers, and advertisements in The New York Times from 1972 to 2001. The study found that 83% of peer-reviewed papers and 80% of internal documents acknowledged that climate change is real and human-caused, but only 12% of advertisements did so, with 81% expressing doubt. The study concluded that ExxonMobil helped advance climate science but promoted doubt in its advertisements. ExxonMobil and the Independent Petroleum Association of America criticized the study, saying it used incomplete data from Greenpeace, that the authors were involved in the #ExxonKnew campaign, and that the Rockefeller Family Fund partially funded the research. The IPAA also said Exxon and Mobil were separate companies during much of the time studied, claiming that Exxon did most of the climate research and Mobil did most of the advertisements.
In 2023, the journal Science published a paper stating that ExxonMobil’s scientists accurately predicted global warming from 1977 to 2003 and skillfully modeled how much CO₂ would cause dangerous warming. The paper’s authors said that while scientists and governments shared their knowledge with the public, ExxonMobil worked to deny it.
Funding of climate change denial
ExxonMobil has been the most active among major oil companies in discussions about climate change. In 2005, while other major oil companies began exploring alternative energy sources, ExxonMobil reaffirmed its focus on oil and gas. A 2007 study by the Union of Concerned Scientists found that ExxonMobil used similar methods, groups, and people as the tobacco industry did when it denied the link between smoking and lung cancer. ExxonMobil claimed it was not similar to the tobacco industry.
A 2015 study in Nature Climate Change stated that ExxonMobil may have played a key role in supporting groups that spread information opposing scientific findings about climate change.
During the 1990s and 2000s, ExxonMobil supported efforts to deny the effects of global warming internationally. It influenced the United States’ decision not to join the Kyoto Protocol, an agreement to reduce greenhouse gas emissions. ExxonMobil funded groups that criticized the Kyoto Protocol and tried to weaken public trust in scientific evidence about global warming. It was a founding member of the Global Climate Coalition, a group of businesses opposing regulations on emissions. Between 2000 and 2003, ExxonMobil gave at least $8,678,450 to 40 groups that spread misleading information about climate change.
ExxonMobil supported groups such as the Competitive Enterprise Institute, George C. Marshall Institute, Heartland Institute, the American Legislative Exchange Council, and the International Policy Network. Since the Kyoto Protocol, ExxonMobil gave over $20 million to groups opposing climate change. Between 1998 and 2004, it gave $16 million to groups that questioned the impact of global warming.
In 2006, the Royal Society found that ExxonMobil gave $2.9 million to 39 groups that spread false information about climate change. The Royal Society expressed concern about ExxonMobil’s funding of groups that misrepresented scientific evidence. It also asked ExxonMobil to stop funding climate change denial. Some people criticized this request, saying it unfairly targeted private funding of science.
A study by Drexel University found that ExxonMobil contributed about 4% of the total funding for groups opposing climate change. Much of this money was sent through other groups to hide its source. In 2006, a European watchdog group said ExxonMobil spent large amounts to support think tanks that spread doubts about the need to reduce emissions. It called this practice hypocritical because ExxonMobil also spent money on ads to appear environmentally responsible.
Between 2007 and 2015, ExxonMobil gave $1.87 million to Republican members of Congress and $454,000 to the American Legislative Exchange Council. ExxonMobil claimed it did not fund climate change denial. It was part of ALEC’s "Private Enterprise Advisory Council" but left ALEC in 2018.
In 2007, ExxonMobil’s vice president for public affairs said the company had stopped funding the Competitive Enterprise Institute and "five or six" similar groups. Greenpeace listed five groups ExxonMobil had stopped funding and 41 others it still supported.
In 2008, ExxonMobil said it would reduce funding to groups that distracted from the need to address climate change. However, it still supported over 20 groups that questioned climate science. A 2005 Royal Society survey found ExxonMobil gave $2.9 million to 39 groups that denied scientific evidence about climate change.
The Union of Concerned Scientists published a report titled Smoke, Mirrors & Hot Air, which criticized ExxonMobil for funding a disinformation campaign similar to the tobacco industry’s. It said ExxonMobil gave about $16 million from 1998 to 2005 to groups that spread doubt about climate science. ExxonMobil claimed it no longer funded these groups, but Greenpeace challenged this claim.
To learn more about hidden funding, U.S. senators wrote to companies. A representative from Koch Industries refused, saying it would violate the company’s rights.
Greenpeace and researchers linked scientists who denied climate change—such as Fred Singer, Fred Seitz, and Patrick Michaels—to groups funded by ExxonMobil and Philip Morris USA. These groups include the Cato Institute and the Heritage Foundation. Groups like the George C. Marshall Institute have also been criticized for their ties to fossil fuel companies.
Lobbying against emissions regulations
Lee Raymond was the chief executive officer of Exxon and ExxonMobil from 1993 to 2006. He was one of the most open critics in the United States of rules meant to reduce global warming.
In February 2001, during the early years of President George W. Bush’s administration, ExxonMobil’s top lobbyist in Washington wrote to the White House. The letter urged that people who had worked under the Clinton/Gore administration and supported strong climate action be excluded from roles in the United States delegation to the working groups of the United Nations’ Intergovernmental Panel on Climate Change (IPCC). The letter suggested replacing them with scientists who questioned the scientific agreement about climate change. The chairman of the IPCC, Robert Watson, was later replaced by Rajendra K. Pachauri, who was viewed as more favorable to industry interests. A spokesperson for ExxonMobil stated the company did not take a position on the IPCC chairmanship.
On June 14, 2005, ExxonMobil announced it would hire Philip Cooney. This happened four days after Cooney left his job as chief of staff of the Council on Environmental Quality in the Bush White House. Two days earlier, a non-profit organization called the Government Accountability Project released documents showing Cooney had changed government scientific reports to make the science behind the greenhouse effect seem less certain.
Some researchers say ExxonMobil’s strategy may have delayed global action on climate change. Others are unsure if the company’s different actions would have led to a different result.
Acknowledgement of climate change
Internal ExxonMobil documents revealed that after the company released its first public statement in 2006, admitting that burning fossil fuels contributes to climate change, CEO Rex Tillerson and other executives tried to reduce public worry about climate change by questioning how serious its effects would be.
In 2007, ExxonMobil first told its shareholders about the financial risks climate change might pose to the company’s profits. However, this information was included in standard, repeated language in a report to shareholders, which mentioned potential threats from "laws and regulations related to environmental or energy security matters" and "global climate change." The report did not directly address the risks caused by climate change itself or by the company’s role in it. In January 2007, Kenneth Cohen, ExxonMobil’s vice president for public affairs, stated, "we know enough now—or, society knows enough now—that the risk is serious and action should be taken." On February 13, CEO Rex W. Tillerson acknowledged that the Earth was warming as carbon dioxide levels rose, but he also defended the oil industry and predicted that oil and gas would remain central to global transportation as energy demand increases by about 40% by 2030. He claimed there was no major alternative to oil in the coming decades and that ExxonMobil would continue to focus on producing petroleum and natural gas.
In April 2014, ExxonMobil released a report that publicly recognized climate change as a risk for the first time. The report suggested that a growing global population, higher living standards, and better access to energy might lead to lower greenhouse gas emissions.
ExxonMobil has criticized the fossil fuel divestment movement, stating on its blog in October 2014 that divesting from fossil fuels was "out of step with reality" and that "not using fossil fuels is like not using energy at all."
ExxonMobil regularly uses an internal estimate of the cost of carbon dioxide emissions in its business planning. In December 2015, the company said that if carbon regulations became required, the best solution would be a carbon tax.
State and federal investigations
In 2012, some environmental groups began considering using RICO laws against the fossil fuel industry, similar to how these laws were used against Big Tobacco. In May 2015, Senator Sheldon Whitehouse wrote about this idea in The Washington Post. Later that year, on October 14, Representatives Ted Lieu and Mark DeSaulnier sent a letter to the United States Attorney General (US AG), asking if ExxonMobil broke any federal laws by not sharing honest information about climate change. When asked about the letter by The Guardian, an ExxonMobil spokesperson said, "This is complete nonsense. We have a 30-year history of researching climate change without interruption." On October 30, 2015, more than 40 environmental and social justice organizations also wrote to the US AG, requesting a federal investigation into whether ExxonMobil misled the public about climate change. Former Vice President Al Gore and the three Democratic candidates for president at the time called for a Department of Justice investigation.
On October 29, 2015, Senators Sheldon Whitehouse, Richard Blumenthal, Elizabeth Warren, and Ed Markey sent a letter to ExxonMobil, questioning their donations to Donors Trust, a group that funds climate change denial. In January 2016, Marjorie Cohn, a law professor at the Thomas Jefferson School of Law, called for the revocation of ExxonMobil’s articles of incorporation.
In 2015, New York Attorney General Eric Schneiderman began an investigation to determine if ExxonMobil’s statements to investors matched the company’s long-term scientific research. In October 2018, based on this investigation, the State of New York sued ExxonMobil, claiming the company deceived shareholders by downplaying the risks of climate change to its business.
Following reports based on internal Exxon documents, which showed that in the 1980s and 1990s Exxon used climate research in its business planning while publicly claiming the science was uncertain, the California Attorney General started an investigation into whether ExxonMobil lied to the public or shareholders about climate change risks, possible securities fraud, and violations of environmental laws. ExxonMobil denied any wrongdoing.
On March 29, 2016, the attorneys general of Massachusetts and the United States Virgin Islands announced investigations. Seventeen attorneys general were working together on related cases. ExxonMobil called the investigations "politically motivated." In June, the attorney general of the United States Virgin Islands agreed to drop a subpoena, and ExxonMobil sued Massachusetts Attorney General Maura Healey. In 2019, the U.S. Supreme Court ruled in favor of Massachusetts, allowing the case against ExxonMobil to continue. This decision meant ExxonMobil could no longer refuse to provide records the attorney general needed for the investigation into whether the company hid knowledge that fossil fuels contribute to climate change and intentionally misled the public and investors.
Relations with the Rockefeller family
Beginning in 2004, the family members of John D. Rockefeller Sr., mainly his great-grandchildren, used letters, meetings, and requests from shareholders to encourage ExxonMobil to recognize climate change, stop denying its effects, and move toward clean energy. In 2013, after a shareholder request called for reducing emissions, ExxonMobil’s CEO, Rex Tillerson, asked, "What good is it to save the planet if humanity suffers?"
In March 2016, the Rockefeller Family Fund announced plans to stop investing in ExxonMobil. The Rockefeller Brothers Fund and the Rockefeller Family Fund supported reports that suggested ExxonMobil knew more about the dangers of global warming than it had shared. David Kaiser, grandson of David Rockefeller Sr. and president of the Rockefeller Family Fund, stated, "The company seems to be morally bankrupt." Valerie Rockefeller Wayne, daughter of former Senator Jay Rockefeller, said, "We hope ExxonMobil will admit what it has done—these years of denying the problem." In November 2016, ExxonMobil accused the Rockefeller family of planning a secret attack against the company.
In December 2016, Kaiser wrote, "Our criticism has a certain historical irony. John D. Rockefeller founded Standard Oil, and ExxonMobil is Standard Oil’s largest direct descendant. In a way, we were turning against the company where much of the Rockefeller family’s wealth was created."
Other climate change activities
Starting in 2002, ExxonMobil spent up to $100 million over ten years to create the Global Climate and Energy Project at Stanford University. This project aimed to develop technologies that help provide energy without increasing greenhouse gases. The Union of Concerned Scientists stated that funding academic research has given the company a more positive image, while the company also supports groups that promote certain ideas or causes to spread misleading information.
Board shakeup
In 2021, hedge fund Engine No. 1, which disagreed with ExxonMobil's approach to climate change, placed three individuals on ExxonMobil's board with support from large investment groups. Ric Marshall, an executive director at ESG Research at MSCI, stated, "This shows that investors are taking climate change more seriously. It also shows that they disagree with the way Exxon's board has been handling climate issues."