Michael Brune is the executive director of the Sierra Club, an American environmental organization founded by preservationist John Muir in 1892. Brune was appointed to his position as executive director in January 2010.

Prior to working for the Sierra Club, Brune was the executive director of the Rainforest Action Network for seven years. He also worked as an organizer for Greenpeace.

In 1999, while working at the Rainforest Action Network, Brune ran a successful campaign to get Home Depot stores to stop purchasing and selling wood from old-growth forests. Time magazine listed this as its top environmental story of that year.

Brune is a regular contributor to the Huffington Post, a progressive website founded by Arianna Huffington, as well as Daily Kos.

In 2008 he published a book called Coming Clean — Breaking America’s Addiction to Oil and Coal.

In 2014 Brune was confirmed as the Hillary Institute of International Leadership’s Hillary Laureate in recognition of his work on Climate Change issues. He was then awarded, jointly with Amazon Watch’s Atossa Soltani, the four yearly Hillary Step prize.