Global warming first became personal for me in 2010. I was backpacking in the incomparable Wind Rivers in western Wyoming. I can’t tell you how much, over many years, I have loved those mountains, the wildest great range of the Lower 48; my tent was the only human thing on the shores of a lake a mile long.

But the human imprint had arrived. Hillsides had turned brown with dying pines, acres were littered with gray dead tree trunks. This was the work of bark beetles no longer controlled by cold winters, and you can see it now all over the American West.

Bark beetles were a “known unknown” of global warming. In a 1990 report, the Intergovernmental Panel on Climate Change (IPCC) had already warned that climate change could bring outbreaks of harmful pests, but I don’t think anyone predicted the specific bark beetle disaster. As for the “unknown knowns,” I recently went snorkeling in Yucatan: a deeply sad experience. We have long been warned that the miraculous pageant of coral reefs could dwindle to a miserable remnant … but already?

21st-century climate reminder: ‘That happened faster than I expected.’

The motto for 21st-century climate science might be, “That happened faster than I expected.” Antarctic researcher Christina Hulbe suggested this to some colleagues a few years ago, and indeed the dwindling of the Arctic Ocean ice pack and the forces promoting disintegration of the Greenland Ice Sheet and Antarctic ice shelves have come decades earlier than expected. But other features of climate change are also showing up sooner than many climate scientists expected.

There’s a stunning example in British author Mark Lynas’s essential new book, Our Final Warning: Six Degrees of Climate Emergency (HarperCollins-Fourth Estate, 2020). It’s an update of his 2007 book Six Degrees: Our Future on a Hotter Planet, also a must-read for anyone concerned about the future of our civilization and our planet. Both books give us a ladder of chapters, each reporting findings for what scientists expect to happen at a given level of global warming. Lynas starts with one degree above pre-industrial temperatures, a level not reached in 2007 but passed in 2016. He continues through two, three … up to six degrees, a planet so catastrophically different from the present that science can barely imagine it.

In his 2007 chapter on three degrees of warming, Lynas wrote about monster storms. A fine writer, he brought the science alive with a vivid description of an imaginary 2045 hurricane dumping enormous amounts of rain on – well, a random American city, he picked Houston. In his present book, he repeats the description, now moved up to the one-degree chapter, to remind us of what already happened in 2017 when hurricane Harvey devastated Houston.

Harvey’s behavior was an “unknown unknown.” There appears to be an increasing tendency for hurricanes to “stall” and hammer a place for days, and some kind of slowing down may also be showing up in prolonged heat waves and cold outbreaks. Some experts explain this in terms of the decreased latitudinal temperature gradient – never mind, a technical debate. The point is that some consequences of global warming won’t be imagined at all until they hit us. To be sure, half a century of scientific reports have made clear that there would be climate surprises. And since we are well-adapted to the present climate, most surprises will be unwelcome.

Lynas does not talk much about surprises. His book concentrates on the “known knowns,” on what scientists think are the most likely outcomes at each level of warming. He has scanned thousands of technical papers in journals that even most scientists rarely peruse. He has talked with the experts; and he lays out the best information he can find.

I won’t go over it all here. If you don’t know the basic facts, you really should read the book. Suffice it to say that at three degrees above our grandparents’ climate, it’s hard to see how the world could sustain a broadly prosperous and tolerant civilization such as many now enjoy. At four degrees, maintaining any kind of civilization at all becomes problematic. And it’s more likely than not that today’s young people will experience such global temperatures (or worse) in their lifetimes, unless we make radical policy changes.

How good is Lynas’s science? There’s a risk of confirmation bias: no matter how hard you try, anyone concerned about climate change will be inclined to pay greater attention to worrisome findings than to soothing ones. I’ve struggled with this myself, but I am confident that Lynas correctly reports what the peer-reviewed literature describes.

But is the literature itself biased? Have referees and journal editors, and for that matter researchers, focused on investigations of dangers? Yes, and that’s the right thing to do. It’s appropriate to give attention to, say, a calculation of which cities will become death traps during heat waves, or how far the yields of major crops will decrease. All of the many kinds of disasters that Lynas sees as likely are at least plausible. Many of them are in cold fact much more likely to happen than not, and some are already underway.

It’s happening faster than we expected. The world has temporized for so long that decisive action must begin – ahem, twenty years ago – but it’s not quite too late. The IPCC has explained that the decisions made in the next 10 years will determine the climate of the planet for the next 10,000 years or more. Even if nations all meet their pledges for the Paris Climate Agreement (which few of them are doing), our destiny is three degrees or more: policies must change radically and immediately. So the entire future of human civilization depends on what we do, us, here, now. Who can grasp that? It sounds like we’ve wandered into a science-fiction movie. But it’s just geophysics.

Sometimes history balances on the point of a needle. For example, a few thousand votes in a close race could choose a senator; the vote of that single senator could make the difference between strong action by the United States and no action at all. And the world will take notice.

12 more books for summer reading lists

Between now and November every American can work for candidates in key Senate races, or not. What they decide to do will be more important than anything that almost any other group of humans has ever done. I know, I know, it’s not possible, who wants such responsibility … but there it is. It’s all on us, here, now.

Spencer Weart is emeritus Director of the Center for History of Physics at the American Institute of Physics. His publications include The Discovery of Global Warming and a much larger history/science website.