Leonardo DiCaprio was one of dozens of celebrities, politicians, scholars, and CEOs who signed an open letter to President Joe Biden asking him to take the threat of climate change seriously. “Congratulations! Your inauguration marks a turning point in history for the United States of America and for the world. The task ahead is enormous: the need to tackle the devastating global health and economic crises, and the need to unite Americans in doing so, is urgent,” it reads, adding that the 2020s is “the most decisive decade in human history to confront the climate crisis.”