How Much Nature is Enough? That's the question the NYT asks today, and it's worth an answer. But first, a little background.
We are living, biologists like to remind us, in the Sixth Extinction: a loss of species as great as, and far, far more rapid than, the meteoric disaster that wiped out the dinosaurs.
It is an unfortunate truth that we have already doomed hundreds of thousands, and probably millions, of species of our fellow living beings to extinction. Many are disappearing unknown to us, never even described by science. With business as usual, we may wipe out half of life's variety this century.
No one knows the true implications of this. It is true that sometimes ecosystems can survive, heal, even thrive with fewer or different species than they had we went to work on them. It is also true that sometimes killing off just one or two key species can cause a spiral of collapse, leaving a wasteland behind. As has been said, species are the rivets holding our ecosystems together and we're knocking them out one by one, not knowing when the structure will collapse. "The first rule of intelligent tinkering is to save all the parts."
There are three responses. The first is the one everyone sane believes we ought to pursue: try to save all the parts. There's no doubt that the preferred option is the preservation of what some US enviros term "The Big Wild" - huge tracts of protected nature. But the engines driving habitat destruction and species extinction are incredibly powerful. It seems probable that in even in the best case scenarios, we're going to lose a lot. Which brings us to the second and third responses: pick and choose which parts we save, and save the plans for the parts. These are the subject of the Times piece.
The pick-and-choose approach is known as the "hotspots" strategy. The gist: identify threatened habitats with the greatest biological diversity and use your scarse conservation funding to protect them. It's not stupid, but the problem is that science is increasingly discovering that ecosystems are more interconnected and complex than previously understood, and that unless hotspot reserves are really big, species there continue going extinct.
The last approach has to do with documenting and preserving the DNA of species we know will soon be extinct. Rather than saving the parts, these frozen genetic zoos, (or "zooz" as they're increasingly called) save the genetic instructions for the manufacture of those parts. While saving the DNA of an extinct species is certainly better than letting it slip into oblivion undocumented, huge problems remain.
The first is that we're not certain we can ever bring these creatures back. As efforts to clone the extinct Thylacine (or "Tasmanian Tiger") have shown, it's really hard to bring back even a single individual, much less a viable population.
But even if you could revive a species, what you have may not be the same as what you lost. Ecosystems are by definition the interaction of species. We have no idea how to even begin reconstructing those interactions. And the critters themselves may not be the same when cloned. As the Times notes,
"[B]anking nature in a deep freeze or database of gene sequences cannot capture context. For instance, even if a vanished bird was someday reconstituted from its genes, would it warble with the same fluency as its ancestors?"
So which path do we choose? Saying we need all three approaches is, of course, not really an answer at all. The fact is, we need something altogether new. A strategy which cannot produce success is not a good strategy, however better than the known alternatives it appears.
Where might success come from? I don't know, but I think there are hints here: in the vision of a Buffalo Commons (wherein the Great Plains are rescued from economically-marginal farming and turned into a giant bison sanctuary and tourism destination); the idea of cataloging, and quickly, the composition of the Earth's biosphere (the All Species Foundation wants to document every species on Earth, while others are sequencing all the genes found in the Sargosso Sea); and efforts to leapfrog the world's poorest peoples over the stage of industrialization which demands massive resource exploitation.