Man-Made Climate Change: What did governments know?

The International Court of Justice issued a landmark ruling in July 2025 declaring that a “clean, healthy, and sustainable environment” constitutes a human right, and that states have a legal obligation under international law to prevent climate harm. This decision has reignited debates over whether governments knew about the dangers of anthropogenic climate change long before they publicly acknowledged them. Recent research into government documents, scientific reports, and historical records suggests many nations were aware of the risks decades earlier than they admitted. The study titled Early Warnings: Government Knowledge of Climate Change and Legal Responsibility for Climate Harm examines public records, scientific findings, and archival materials to determine when major greenhouse gas emitters recognized the causes and potential consequences of climate change. The analysis reveals that numerous governments understood the risks far earlier than they claimed, strengthening the case for holding these states accountable for their failure to act in time to prevent catastrophic warming. In the United States, evidence shows awareness of climate change dates back to the early 1950s. The U.S. Air Force’s Cambridge Research Center published a meteorological compendium in 1951 that included discussions on carbon dioxide and its impact on climate. By 1958, Dr. Charles Keeling began measuring atmospheric CO₂ levels at Mauna Loa Observatory in Hawaii. His initial three years of data, released in 1960, showed seasonal fluctuations and a steady rise in CO₂ concentrations. He noted a possible link between fossil fuel consumption and rising emissions. These measurements became known as the Keeling Curve, a key indicator of increasing greenhouse gases. Keeling’s work led to his participation in a 1963 conference organized by the private Conservation Foundation, titled Effects of Increasing Atmospheric Carbon Dioxide. The conference warned that burning fossil fuels would increase atmospheric CO₂, leading to higher global temperatures. It also highlighted how temperature increases had already altered the distribution and abundance of economically important fish species. The report cautioned that continued reliance on fossil fuels could lead to temperature rises sufficient to melt polar ice caps and potentially cause widespread extinction of life forms. The organizers distributed 700 free copies of the report to university and government libraries nationwide, suggesting that political leaders and other members of the U.S. government likely encountered the document. In July 1977, President Jimmy Carter received a memo from the Office of Science and Technology Policy warning about the “release of fossil CO₂ and the possibility of a catastrophic climate change.” This internal communication underscores growing concerns within the U.S. government about the implications of unchecked emissions. These historical records provide critical context for ongoing legal battles seeking accountability from governments for their role in exacerbating climate change. As the International Court of Justice’s ruling reinforces the legal obligations of states, the question of when and how governments became aware of the crisis continues to shape the trajectory of climate litigation and policy reform.