The main argument for this view, aside from the moral one that it is wrong for us to extinguish any species, is that species diversity keeps ecosystems functioning. Functioning ecosystems in turn provide economically valuable services; for instance, healthy forests around cities keep local water supplies clean. Hard scientific data back up both those claims—but only at the level of individual ecosystems, not the whole planet. “There is not a single scientific paper that shows a loss of ecosystem services when you change the total global number of species,” Kareiva says.
The hotspot concept, he goes on, “doesn’t have a scientific basis at all. When we say we care about biodiversity, we mean wherever you live, Montana or Tanzania, you don’t want to lose so many species that your ecosystem just won’t function. The goal might be, nowhere in the world do we lose half our species. If we lose that much, that place is gone.” Boitani’s long-term priority is similar. It is “to find a stable relationship between humans and other species,” he says. “Stop the negative trend. Find a relation of coexistence and tolerance, even if it means we have to lose 50 percent of the species. I’m ready to sign off on that if it means what is left will last.”
That view is anathema to hotspot proponents. “The notion that biodiversity loss of any kind is acceptable is just not acceptable,” Hoffmann says. “We don’t believe that extinction is inevitable—human-mediated, fast-tracked extinction should not be inevitable.” From that standpoint, accepting the reality that we are causing extinctions every day and, as global warming accelerates, are soon going to be causing many more is unforgivably unambitious. The counterargument is that trying to preserve the whole planet in some kind of ecologically intact form is in fact far more ambitious than just focusing on the 2 percent of land surface that happens to be in hotspots.
Biodiversity hotspots were a useful conceptual shortcut—a quick way of figuring out where to begin with the daunting task of saving the world. By focusing efforts on the total number of species, they allow conservationists to avoid the hard science required to decide which species matter most to ecosystems and the hard choices required to decide which species matter most to us. But we’ll come closer to making real conservation progress, say Kareiva and other scientists, when we face up to those choices. “We’re the stewards of the planet,” Kareiva declares. “We get to choose its future. Let’s admit that.”
Note: This article was originally printed with the title, "Are Hot Spots Key to Conservation?"