When I read “Six Degrees,” Mark Lynas’s blistering warning, way back in the good old days of 2007, the experience scared the shit out of me. I needed that fright and since then I’ve strived to keep on top of our future in a globally warmed world by reading as much as I can in the popular, and sometimes scientific, press. Some brilliant works have ensued over the thirteen years since “Six Degrees,” but none of them had quite the same sensible framing. So Lynas’s complete remake of that classic, just released, “Our Final Warning: Six Degrees of Climate Emergency,” had to jump to the top of my reading pile. We are now in a one degree world, as Lynas opens the book with, and over the course of this sober, stunning book, he takes us through what the latest science says two degrees, three degrees, four degrees. five degrees, or even six degrees would look like, plus how soon or likely each of these outcomes looms. Lynas is a robustly fair analyst: in a couple of cases, the prognosis is slightly improved from 2007 but mostly matters are worse. “Our Final Warning” is brilliantly organized and the writing is clear and elegant. If you read one global warming book in 2020, this should be it. As for me, I’m more than shit scared now, I’m bereft. Unless we act, I’ll see in two degrees in a decade-plus and maybe three degrees before I die; my grandchildren face four degrees and human civilization under threat.