Are we killing ourselves by degrees?

kw: book reviews, nonfiction, global warming, polemics

See my post on June 23 for background about my contention that climatic heating greater than 4°C due to CO₂ emission is implausible. I've just finished reading Six Degrees: Our Future on a Hotter Planet by Mark Lynas, an environmental activist who writes for National Geographic Explorer.

The book is well planned and well composed. Lynas has gathered all the effects we might expect at each degree C, from one to six, with a chapter for each degree. If we take the 1950s as a baseline (the author doesn't state his zero point), we're living in a "one degree world" already. The natural progress of the current cycle as outlined by Gerald Bond, that is, the "Bond Event" that began about 500 years ago with the start of the Little Ice Age, and that will run another 500 to 800 years, with a warmer middle (or at least a drier one), is likely to produce another degree of warming entirely without our help. Remember also the brief (decade or so) cooling of the 1960s and '70s. The best (not most frequent) estimate of the "human signal" in all this is half a degree or less.

Thirty-plus years ago I remember straight-line extrapolations made by scientists that warned us the year 2000 could be one or two (some said five) degrees cooler than the 1950s, and that we were in danger of continental glaciation getting started. Those fears are pretty much forgotten now. Today's fears are less likely to be forgotten, because we appear to be augmenting a natural warming cycle.

I don't want to discuss the matter, point by point. This is but one of many new books on the subject, though it happens to be the most conveniently arranged. I'll just make a few more observations as an observer with a geologic worldview.

• In my post linked above I state that the PETM some 55 million years ago was a two degree excursion. Lynas and many others state it was six degrees, and others pick various figures in between. It may have been more than two degrees, but remember it began at a point ten degrees hotter than now. The key element seems to have been release of a lot of methane from the seabed. The rate of release, during each of two thousand-year-long periods, was slightly smaller (in terms of carbon per year) than the current human output, which is growing. Methane is about twenty times as effective a greenhouse gas as Carbon Dioxide, and takes a few years to be oxidized to CO₂. Thus most of the heating was due to Methane. To me, it seems like a good idea to gather seabed methane "ice" and convert it to CO₂ before it erupts on its own...and we'd get lots of energy out of the bargain.
• More CO₂ means more acid in the oceans, making it harder for shelly creatures to make their shells, or so it is claimed. Its actual effect is to make the lysocline shallower; the lysocline—the depth below which carbonate shells dissolve—is presently 4km. In the Cretaceous, when the temperature was 15-20 degrees warmer and CO₂ was four or five times as abundant as today, the lysocline was closer to 1km depth, and shelly creatures abounded, since most of them live in water shallower than this anyway.
• Curiously, nobody talks about the "vent clams" and giant tube worms found in the deep ocean around the mid0cean ridges and their hot-water vents. They were there in the Cretaceous, too, and somehow made lots of shells even at depths below the lysocline. Just as diamonds are not stable at the surface, but slowly (millions of years) are reverting to graphite, so if you take a clam shell to a deep part of the ocean (the deepest trenches are 11km) it won't dissolve for many years. In fact, shelly creatures live in the deepest trenches today. The things that do dissolve with seeming rapidity are shells of microscopic foraminifera and radiolarians, which start out less than a millimeter across. But they don't vanish on the way down; they sink to the bottom and very slowly dissolve there.
• I keep reading about how living creatures "can't adapt" to this or that change. Yes, evolution is rather slow, but in short-lived creatures (most of our furry and feathery friends reproduce yearly or oftener) it can proceed with stunning rapidity. Let us remember that, the greater percentage of a generation gets killed, the greater the likelihood that the next generation will be substantially different from their ancestors. That is the essence of Punctuated Equilibrium, for which see the writings of Stephen Jay Gould and Niles Eldredge. Bottom line: Ten years is ten generations for a songbird or rodent. That's plenty of time for the critters to move half a continent away if needed. Only a few offspring with wanderlust need survive for a species to make a large move.
  

Author Lynas is rather pessimistic about people's willingness to sacrifice for the next generation. I tend to agree. I expect the human race of five hundred years from now will primarily be using sustainable energy, because the cheap and easy stuff we use now will be gone, and for no other reason. In part, that's also enough time for evolution to have worked on the human psyche, but in which direction I dare not hazard a guess! BUT: The larger the number of people living then, the less evolutionary change there will have been. That's a simple statistical fact.

I am in substantial agreement with about half of the conclusions in the first three chapters, and a much smaller proportion of the rest. Knowing the tendency of both living and nonliving, complex systems to "do what they want," I expect the next generation or two will live in a world about which not one of the current authors has written.