William Ernest McKibben is an American environmentalist, author, and journalist born in 1960 in Palo Alto, California. He has written extensively on the impact of global warming and environmental challenges facing humanity. McKibben is the Schumann Distinguished Scholar of environmental studies at Middlebury College. He has authored a dozen books about the environment, beginning with The End of Nature in 1989, which addressed climate change. His other works include Falter: Has the Human Game Begun to Play Itself Out? published in 2019, and Here Comes the Sun released in 2025, which examines environmental challenges and future prospects. Beyond his writing, McKibben has been active in climate advocacy and leadership. He founded and leads 350.org, a climate campaign group, as well as the Third Act Movement. His work spans journalism, environmental scholarship, and activism.