CAMBRIDGE, Mass. (May 14, 2025)—Major fossil fuel companies such as BP, Chevron, ExxonMobil, and Shell had highly accurate scientific knowledge of the dangers their products pose to the global climate and people for decades, and yet worked actively to sow disinformation, deceive the public, intimidate scientists and evolve their greenwashing tactics, evidenced in a new report released today by the Union of Concerned Scientists (UCS).
“The evidence laid out in UCS’ latest report exposes what fossil fuel companies knew about the dangers of their products, when they knew it, and how they developed and continue to carry out deliberate deception campaigns to delay climate action, grow their profits, and preserve their business models at the expense of people and the planet,” said Kathy Mulvey, a report author and accountability campaign director for the Climate and Energy Program at UCS. "The report builds on the diligent efforts of many social scientists, investigative journalists, litigators, members of Congress and researchers on congressional committees, and public interest groups working to hold fossil fuel companies accountable."
The report, “Decades of Deceit,” draws on a wealth of primary sources that further strengthen the evidence behind dozens of legal cases worldwide against fossil fuel companies for knowingly causing climate damages and funding a decades-long campaign to undermine science and delay climate action, including:
- In 1959, an American Petroleum Institute event featured renowned scientist Edward Teller as the keynote speaker where he warned fossil fuel executives that rising carbon dioxide (CO2) levels in the atmosphere caused by burning fossil fuels could accelerate the melting of icecaps and lead to coastlines being submerged.
- In 1984, Exxon scientist Henry Shaw told company leadership, “We can either adapt our civilization to a warmer planet or avoid the problem by sharply curtailing the use of fossil fuels,” after which Exxon scaled back its climate research and invested in a climate science disinformation campaign to mislead the public and block government action.
- In 1988, a confidential Shell report explicitly acknowledged the burning of fossil fuels as a primary driver of the buildup of CO2 in the atmosphere and warned that global warming could “create significant changes in sea level, ocean currents, precipitation patterns, regional temperature and weather.” The report notes, “by the time the global warming becomes detectable it could be too late to take effective countermeasures to reduce the effects or even to stabilize the situation,” adding “the potential implications for the world are . . . so large that policy options need to be considered much earlier.”
Currently, one in four people in the United States live in a state, territory, or municipality that is suing a major fossil fuel corporation to hold them accountable for climate deception, damages, or racketeering. “Decades of Deceit” underscores why fossil fuel companies fear legal accountability and have used procedural tactics to delay consideration of these lawsuits on their merits—in some cases for nearly eight years. In a troubling development, President Trump signed an executive order last month attacking states’ rights to protect their residents from the climate crisis through legislation and litigation. This month, in an effort to block climate litigation and Superfund-style accountability laws, President Trump’s Department of Justice filed lawsuits against four states. The fossil fuel industry has also signaled interest in reviving past attempts to shield itself from litigation in the United States by lobbying for a “liability waiver.” This report paints a damning portrait of corporate malfeasance and underscores the need for Congress and the Trump administration to uphold the courts and state-level policymaking as avenues for those harmed by fossil fuel industry misconduct to pursue justice.
“The fossil fuel industry has spent decades trying to bury the very scientific consensus its own research proved: the continued burning of fossil fuels is incompatible with a livable climate,” said Dr. Delta Merner, a report author and lead scientist for the Science Hub for Climate Litigation at UCS. “A healthy, safe future for people and the planet necessitates a concerted effort to hold major oil, gas and coal corporations accountable for the avoidable harm they’ve caused and to prevent further injury, damage and loss of life.”
“There’s a clear story here of fossil fuel companies shifting tactics over the years while maintaining the same goal—private profit subsidized by sacrificing public goods like clean air, unpolluted water and a stable climate,” said Laura Peterson, a report author and senior analyst for the UCS accountability campaign. “Tactics have varied from outright denial of climate science to greenwashing, standing up front groups to mislead the public, and attempting to intimidate climate advocates.”
Examples of such dubious tactics highlighted in the UCS report include:
- In 2025, court documents allege a coordinated scheme to hack into the email accounts of staff members at UCS and several other public interest organizations, all of whom were working to hold fossil fuel companies accountable for their role in climate change. The documents, together with related reporting, suggest the U.S. government possesses evidence the criminal scheme was indirectly paid for by ExxonMobil and that one of its lobbying firms, the Washington, D.C.-based DCI Group, provided a list of “targets” to a middleman linked to the hackers and sent the fruits of the hacking to the oil and gas company.
- In 2023, Chevron gave more than $7 million to a group masquerading as a grassroots community initiative that was created by the Western States Petroleum Association to fight a California windfall tax on oil companies.
- In 2021, former ExxonMobil Senior Director of Government Affairs Keith McCoy admitted the company used front groups to “aggressively fight” against climate science.
The report concludes by urging affected communities, experts, consumers, public prosecutors, litigators, investors, financiers, business partners, regulators, and policymakers to use all lawful means to hold fossil fuel companies accountable. UCS calls for massive public pressure on these corporations to meet key demands, including:
- Cease disinformation and greenwashing on climate science, public policy, and corporate actions;
- Stop obstructing science-informed public policy and its implementation;
- Pay an equitable share of the costs of climate damages, climate adaptation, and the environmental, social, and systemic impacts of fossil fuel products and production; and
- Accelerate actions, investment, and business planning for a fair and fast phaseout of fossil fuels worldwide.
“As fossil fuel companies brazenly brandish unbridled influence within the Trump administration, we need members of Congress willing to stare corruption in the face and champion justice through climate accountability,” said Mulvey. “Congress must protect the rights of states and communities to hold ExxonMobil, Shell, the American Petroleum Institute, and other fossil fuel polluters accountable for worsening the climate crisis through their decades of deceit. Any effort to shield the fossil fuel industry from legal liability must be resoundingly denied.”
For all other materials, including an executive summary, corresponding blog posts and an interactive timeline tool, click here.