For decades, oil and gas magnate Charles G. Koch and his late brother David fought vigorously for environmental deregulation, including by supporting groups that sow doubt about the science of manmade climate change. Foundations linked to Koch gave at least $9.6 billion to 15 Project 2025 groups since 2020. But four of the lesser-known families — Bradley, Scaife, Seid, and Uihlein — gave even more, and all six family fortunes helped to fund Project 2025 groups that have denied the science of manmade climate change.