President-elect Donald Trump’s pick to head the Environmental Protection Agency has worried some environmentalists, who say Scott Pruitt will roll back many of the policies put in place to deal with climate change.

We have a couple of perspectives on climate change today.

Guy McPherson is a conservation biologist and professor emeritus at the University of Arizona. McPherson’s positions do not, as he points out in his talks and writings, necessarily agree with the conventional wisdom among scientists who study climate change.

Jesse Anttila-Hughes is an economics professor at the University of San Francisco, although he has a background in the sciences.