Bill McKibben is an American environmentalist, author, and journalist known for his work on climate change and sustainability. He gained prominence with his 1989 book, The End of Nature, which is considered one of the first books for a general audience about global warming. McKibben founded the grassroots climate campaign 350.org, which aims to reduce atmospheric carbon dioxide levels to a safe 350 parts per million. In addition to his writing and activism, McKibben is a co-founder of Third Act, an organization that mobilizes older Americans to take action on climate issues. He has received numerous awards for his environmental work, including the Gandhi Peace Award and the Thomas Merton Award.