This week, world leaders are gathered at the United Nations' COP26 summit in Glasgow, Scotland, to discuss what to do about the climate crisis. Gus Speth knows what brought us to the edge of this climate emergency. President Carter and all the presidents who followed knew, too.

The United States government knew that climate change was an impending disaster. They knew that burning fossil fuels could drive the world into crisis. And yet for the last half century, American leaders put their feet on the accelerator of fossil fuel consumption and pushed down hard.

The actions of American leaders “on the national energy system over the past several decades are, in my view, the greatest dereliction of civic responsibility in the history of the Republic,” writes Speth.

Gus Speth is now telling the story of how and why this happened. Speth, who lives in Strafford, Vermont, is a luminary in the environmental movement. He served as chair of the U.S. Council on Environmental Quality during the Carter Administration. He went on to lead the U.N. Development Program, served as Dean of the Yale School of Environment and co-founded the World Resources Institute and the Natural Resources Defense Council. He was a professor at the Vermont Law School and is now part of The Next System Project, which addresses systemic challenges confronting the U.S.

Speth’s latest book is They Knew: The Us Federal Government’s Fifty-Year Role in Causing the Climate Crisis. On this week's Vermont Conversation, Speth talks about what radicalized him, leading him to go from government insider to getting arrested in front of the White House protesting the Keystone XL pipeline.