Fossil fuel mogul and billionaire David Koch has stepped down from the board of New York’s American Museum of Natural History after 23 years. He handed in his resignation at the December board meeting, but it just came to light late Wednesday.

Beka Econompoulos, the director of the pop-up Natural History Museum (not to be confused with the American Museum of Natural History) called Koch’s departure “a victory for scientists, climate activists and museum professionals who have been calling for museum’s to break ties with Koch and other fossil fuel interests.”

Last March, a letter signed by 148 leading scientists - including James Hansen and Danny Harvey, a professor of geography and climatology at the University of Toronto - called for Koch’s resignation.