GENEVA / WASHINGTON DC, July 15, 2026 — Governments of many countries responsible for the greatest shares of greenhouse gas emissions knew about the dangers of fossil fuel-driven climate change decades before they claimed in court, according to a new report released today by the Center for International Environmental Law (CIEL).
Drawing on government archives, scientific reports, official memoranda, and other records, “Early Warnings: Government Knowledge of Climate Change and Legal Responsibility for Climate Harm” finds that officials in many of the countries that are the world’s largest historical emitters, including the United States, Canada, the United Kingdom, France, Australia, Germany, Norway, and Russia, had credible warnings about the climate risks of fossil fuels from at least the 1960s, and in some cases even earlier.
The report directly challenges arguments advanced by several high-emitting States in recent International Court of Justice (ICJ) proceedings that governments could not reasonably have been expected to act on climate before the late 1980s. Instead, the historical record shows that governments had access to scientific evidence, funded climate research, and discussed the risks of fossil fuel emissions decades before international climate negotiations began in 1995.
The report comes one week before the first anniversary of the ICJ’s landmark climate advisory opinion (July 23), which affirmed that States have binding obligations under international law to prevent and mitigate climate harm and that failing to uphold those obligations may give rise to legal responsibility. As climate litigation against governments and major emitters accelerates worldwide, with several key hearings scheduled in 2026, the report provides historical evidence that could shape how courts assess when those legal duties first arose.
“Governments have argued that they couldn’t act because they didn’t know. The historical record tells a different story,” said Lindsay Fenlock, CIEL Senior Researcher. “The science establishing the dangers of fossil fuels did not emerge overnight in the late 1980s. Governments were engaging with that science decades earlier. That evidence matters because accountability for the climate crisis depends not only on what governments did or did not do, but on what they knew, and when they knew it,” she added.
The report documents that governments received repeated warnings that continued use of fossil fuels could lead to rising temperatures, sea-level rise, extreme weather, and widespread environmental harm. Yet fossil fuel production and consumption continued to expand long after those risks had become foreseeable.
“What governments knew about the dangers of fossil fuels is not just a matter of historical record; it is a matter of legal responsibility. One of the greatest injustices of the climate crisis is that so much of it was avoidable. Governments in major emitting countries had credible warnings for decades that fossil fuels were warming the planet and putting people and ecosystems at risk. As the ICJ made clear, once States knew, they had a legal duty to act. This report helps establish when that duty arose — and whether decades of delay carry legal consequences today. Amidst deadly heatwaves and steadily rising seas, this report reminds us just how much harm could have been prevented if governments’ early knowledge of climate change had not been met with fossil fuel industry campaigns of denial, deception, and delay. Accountability is overdue and increasingly within reach,” said Nikki Reisch, CIEL Climate & Energy Program Director.
Read the report here.
###
Media Contact
Rossella Recupero, Communications Campaign Specialist: [email protected] | +41 762 165 976
© Bill Chizek Photography – Alamy.