Michael D. Shellenberger (born June 16, 1971) is an American author and journalist who writes on a wide range of topics including free speech, homelessness, and the environment. He is the first endowed professor at the University of Austin, serving as CBR Chair of Politics, Censorship, and Free Speech. He also founded the online newsletter Public. Shellenberger has been active in critiquing the environmental movement, offering alternative views on climate threats and policies. He contends that while global warming is a concern, it is "not the end of the world", and advocates for the use of Genetically Modified Organisms (GMOs), industrial agriculture, fracking, and nuclear power as tools for environmental protection. His views on climate change and environmentalism have sparked debate, with some environmental scientists and academics challenging aspects of his arguments, while others support his positions. Journalistic response to his work has been mixed, with both praise and criticism. Similarly, his positions on homelessness have generated a range of reactions from academics and writers. Shellenberger ran for governor of California in 2018 and 2022 but was unsuccessful in both campaigns.