Alex Steffen (born c. 1968 in Oakland, California) is an American futurist and advocate of 'bright green environmentalism' who writes and speaks about sustainability and the future of the planet. He emphasizes the importance of imagining persuasive, positive possible futures: "It's literally true that we can't build what we can't imagine,... The fact that we haven't compellingly imagined a thriving, dynamic, sustainable world is a major reason we don't already live in one."
