Steven Koonin is one of America's most distinguished scientists, with decades of experience, including a stint as undersecretary of science at the Department of Energy in the Obama administration. In this wide-ranging discussion, based in part on his 2021 book, Unsettled: What Climate Science Tells Us, What It Doesn't, and Why It Matters, Koonin gives a more refined look at the science behind the climate issue than the media typically offers, guiding us through the evidence and its implications. As Koonin explains in this interview, he was “shaken by the realization that climate science was far less mature than I had supposed” and that the “overwhelming evidence” of catastrophic implications of anthropogenic global warming wasn’t so overwhelming after all.