April 29, 2007

Mass Extinction

A poll by the American Museum of Natural History finds that 7 in 10 biologists believe that mass extinction poses a colossal threat to human existence, a more serious environmental problem than even its contributor, global warming, and that the dangers of mass extinction are woefully underestimated by most everyone outside of science.
That's from Julia Whitty's new cover story in Mother Jones. E.O. Wilson has predicted that roughly half of all plant and animal species will be extinct by the year 2100. Normally about one species per million dies off each year. There have been five great extinction waves in the past 439 million years. We're on the verge of a sixth, as "habitat degradation, overexploitation, agricultural monocultures, human-borne invasive species, [and] human-induced climate change" raise the rate of extinction to something like 1,000 to 10,000 times the background rate. (Recently, Joseph Wright and Helene Muller-Laundau have argued that the crisis isn't as bad as thought, although their work is controversial.)

Whitty's piece is very much worth reading, although I tend to wish these articles would really hammer home why humans should care about the loss of biodiversity. It sounds strange to say, but I don't think it's obvious to most people why it's a problem if entire ecosystems up and vanish. Newspapers have been reporting the fact that bees are vanishing en masse, which could threaten $15 billion worth of U.S. agriculture. More concrete examples like this might, I think, get people to perk up. There's no equivalent to the IPCC for the extinction crisis—a body that could hammer out a consensus perspective and urge governments to take action. Why not?

Mind you, climate change is a solvable—though staggering—problem. I'm not so sure anything can be done to halt what Stephen Meyer calls the "The End of the Wild" (Meyer isn't sure, either). Whitty discusses the Wildlands Project, which would create massive linked "corridors" for wildlife, on a scale larger than anything yet contemplated. In the United States, ecologically significant areas such as Florida, the Arctic/Boreal regions, and the Rocky Mountains would be preserved and connected (see this map). But it's also an audacious project: Wildlands advocates estimate that the project could take 100 years or more--and by then, mass extinction will be well underway.

There's certainly something to the Wildlands idea. Right now, wildlife preserves are much too small, and usually cut off from each other, preventing the sort of migration that fosters biodiversity. These reserves are usually surrounded by human activity—farms, urban sprawl, clearcutting—that can affect them, even if they have well-enforced boundaries. The Monteverde Cloud Forest Preserve, an eco-tourist hotspot which covers 30,000 acres and hosts thousands of species, has been drying out because of farming in the surrounding lowlands. Plus, climate change could soon make the whole concept of a static, isolated preserve unworkable. Monarch butterflies, for instance, could soon find the biopreserves in Mexico where they winter uninhabitable in a few decades.

Any serious attempt to at least stem the extinction crisis—even if it can't be stopped—will, it seems, have to take a new approach to wildlife preserves. (As Whitty notes, even Yellowstone National Park has been losing biodiversity.) Meyer recommends setting up sites that protect "broad ecosystem functions... in a dynamic environment rather than species-specific habitat needs or singly-defining (highly peculiar) ecological characteristics." That seems right. Even if something like the Wildlands project is totally unfeasible, governments should be thinking bigger than a few butterfly preserves.

At the moment, governments focus mainly on saving individual species. This amounts to man-made evolution: We decide which species get to stay and which ones go. Pandas are cute and must be saved. Thousands of insects and deep-sea invertebrates that sustain whole ecosystems get little thought. Indeed, the original idea behind the U.S. Endangered Species Act was that the causes of extinction were finite and only a handful of species were genuinely threatened. That notion seems quaint in the face of an impending mass die-off of species we don't even know about. Obviously I don't want to see the ESA junked. Pandas really are adorable and need to be saved. But it's sort of like spitting in a hurricane at this point.

Update: Apologies, I had mischaracterized the Wildlands Project--it would not require large population resettlements, as I had thought.
-- Brad Plumer 8:41 AM || ||