Paula DiPerna, policy consultant, author of Pricing the Priceless (Wiley, 2023) and co-author of Carbon Hunters: Reflections And Forecasts Of Climate Markets In The 21st Century (WSPC,2025), talks about the history of international cooperation on climate change, and Mark Hertsgaard, journalist and co-founder and executive director of Covering Climate Now, and the author of Big Red’s Mercy: The Shooting of Deborah Cotton and A Story of Race in America (Pegasus, 2024), discuss what to expect from the global climate summit underway in Brazil now that the Trump administration is boycotting.