I found Erle Ellis's piece, "The Planet of No Return," badly overblown, even on points where I'm in basic agreement. For instance, I've written a good deal about the huge challenges posed by corporate overfishing to the earth's marine resources. But his claim — one of the few quantifiable facts in the piece — that "wild fish and wild forests have almost disappeared, receding into the depths of our ancestral memory" — is simply not true. The most recent figures I can find are for 2005, when the Food and Agricultural Organization of the United Nations reported that 93.3 million tons of fish were landed as a result of commercial fishing in wild fisheries, compared with 48.1 million tons produced by fish farms. It's true that that number is off the peak of 96 million tons set in 2000, but "almost disappeared" is typical of the airy disregard with which Ellis treats actual data. (He cites three papers in a footnote after his sentence about fisheries, but none contain numbers supporting his claim that they've disappeared; in fact, the latest FAO data indicates 260 million human beings employed in this phantom pursuit). If this seems picayune fact-checking, it in fact reflects a problem for his more fundamental argument, since it indicates that we're still mostly living off the fat of the incredibly fecund land we were born onto, even as we trash it.
Nevertheless, I'll proceed to his claims, however unsubstantiated. His first argument, I think, is that throughout the Holocene we've gotten better at agriculture, producing more food. This is generally true, and it's also irrelevant to the second, more important, argument, which is that this will continue into the post-Holocene even as, he says, we "change the climate system at rates likely unprecedented in Earth's history." To make that second claim, you'd have to look at the likely results of those unprecedented increases in temperature. Which, not surprisingly, scientists have done. To give just one example of literally thousands, all unmentioned by Ellis: a team at Stanford and the University of Washington reported in Science in 2009 that the climate models Ellis apparently regards as correct show "there is a greater than 90 percent probability that, by 2100, the lowest growing-season temperatures in the tropics and subtropics will be higher than any temperatures recorded there to date."Battisti, David. S. and Rosamond L. Naylor. 2009. "Historical Warnings of Future Food Insecurity with Unprecedented Seasonal Heat." Science. 323 (5911): 240-4.The higher temperatures "can be expected to cut yields of the primary food crops, maize and rice, by 20 to 40 percent," they said. (Try imagining a world with 20 percent fewer calories). Moreover, they write, "rising temperatures also are likely to play havoc with soil moisture, cutting yields even further."
In other words, since temperatures are going well beyond anything observed in the Holocene, Holocene-era experience is probably not a very good guide. And indeed we won't have to wait till 2100 to see this happening. Since Fall 2010 a series of extreme weather events tied by climate scientists to global warming (record drought and flooding being the most common, and precisely what you'd expect in a world where warmer temperatures have increased atmospheric moisture by nearly 5 percent above Holocene norms) have led to dramatically higher food prices and a sharp spike in the number of malnourished people on the planet. Poor people, according to December 2011 estimates by hunger researchers at Oxfam, are spending an additional $50 billion annually on food because of these price rises, meaning that many of them are eating far less than they want or need. This is not just a momentary phenomenon. Per capita global grain production peaked in the 1990s and has fallen; total increases in yield have slowed precipitously, just as we leave the Holocene and enter this next world about which Ellis is so glib. By talking broadly about past centuries or millennia, Ellis avoids the questions about our particular, and pivotal, time.
If you ignore both scientific prediction and real-time data, cheerfulness about a globally warmed world comes easy. Comes cheap, actually.