It is a key moment in climate change history that few remember: This week marks the 50th anniversary of the first presidential mention of the environmental risk of carbon dioxide pollution from fossil fuels.

President Lyndon Baines Johnson, in a February 8, 1965 special message to Congress warned about build-up of the invisible air pollutant that scientists recognize today as the primary contributor to global warming.

“Air pollution is no longer confined to isolated places,” said Johnson less than three weeks after his 1965 inauguration. “This generation has altered the composition of the atmosphere on a global scale through radioactive materials and a steady increase in carbon dioxide from the burning of fossil fuels.”

The speech mainly focused on all-too-visible pollution of land and waterways, including roadside auto graveyards, strip mine sites, and soot pollution that had marred even the White House.