While major emitting countries say they can’t be held accountable for climate harm that predates their awareness of the risks, a new report from the U.S. Center for International Environmental Law shows their governments knew decades earlier than they’re now claiming.

“Governments have argued that they couldn’t act because they didn’t know,” CIEL senior researcher Lindsay Fenlock said in a release. “The historical record tells a different story.”

The report follows a 2025 International Court of Justice (ICJ) ruling that governments are obligated to act to prevent climate harm and can be held legally accountable for failing to. Many major emitting countries—including the United States, China, and Canada—stated in the proceedings that they were not aware of climate change risks until the 1980s, and so cannot be held accountable for any failures to act before then.

But CIEL’s report charts out a timeline of climate research and government communications to argue that states knew climate change was a major threat long before that. And this wasn’t just true behind the scenes—ongoing climate research was widely covered in the media, including in newspapers in the earliest years of climate science going back to the late 1800s.

For example, the United States Air Force released a study in 1951 referring to the link between fossil fuels and carbon dioxide, and a decade later, Sen. Clinton Anderson warned then-president John F. Kennedy that humans were able to modify the weather. Charles Keeling and Erik Eriksson were among the scientists at a 1963 conference whose report warned that fossil fuels were warming the planet enough to melt polar ice caps and “annihilate” many life forms. Organizers distributed 700 free copies to government and university libraries, suggesting the research reached U.S. policymakers. The research was also detailed in a 1965 report from President Lyndon B. Johnson’s Science Advisory Committee.

The Canadian government was also aware of climate risks early on, finds the report. Canada held during the ICJ proceedings that although climate change had been identified as a “general issue” in science circles since the end of the 19th century, the world hadn’t begun “to seriously consider the development of an international regime to address the problem” until the 1980s.

But CIEL found research by Canadian oil companies and universities dating back to 1959 to suggest this claim was inaccurate, and adding that government departments were working on a national plan for “the carbon dioxide program” in 1979.

“What governments knew about the dangers of fossil fuels is not just a matter of historical record; it is a matter of legal responsibility,” said CIEL’s climate and energy program director Nikki Reisch. “One of the greatest injustices of the climate crisis is that so much of it was avoidable.”