ANDREA SEABROOK, host:
A snail from the far side of the world - one you've probably never heard of - was declared extinct this week. Okay, normally, that wouldn't be worth mentioning. But this was not your typical extinction.
As NPR's John Nielsen reports, it may be the first one tied directly to global warming.
JOHN NIELSEN: It's called the Aldabra banded snail. It lived on the Seychelles Islands in the Indian Ocean. Biologist Justin Gerlach of Oxford University says it had a very pretty shell.
Mr. JUSTIN GERLACH (Biologist, Oxford University): A dark, purplish blue with an orange band running around it. So it's quite a conspicuous species.
NIELSEN: Or at least it used to be 30 years ago, when scientists were able to pluck them off of fresh leaves all over the islands.
Mr. GERLACH: And then, since then, it's been impossible to find. So the last one that was found was in 1997. And that was collected simply because it was strange and different and the person who saw it didn't know what it was.
NIELSEN: It's hard to prove conclusively that a species is extinct, but Gerlach says he's all but certain that in the late 1990s, the last Aldabra banded snail curled up inside its purplish shell and died.
In the paper in the journal Biology Letters, Gerlach placed the blame on an unusual series of summers that were so hot and so long that they killed off all of the younger snails.
Mr. GERLACH: And so the juveniles just weren't surviving and the adults gradually died off. Until now, we don't have juveniles or adults anymore.
NIELSEN: Gerlach says he found a proof of this in the shells that have been gathered up by collectors. Smaller shells - once numerous - disappeared, when the long, hot summers became common. He suspects - but cannot prove - that these hot summers are a side effect of global warming. If he's right, then this snail has earned itself a grim distinction - it would be the first species in the modern era to become extinct as a direct result of climate change.
It probably won't be the last, says biologist Diane Debinsky of Iowa State.
Dr. DIANE DEBINSKY (Biologist, Iowa State University): I think what we're seeing is the beginning, the tip of the iceberg of extinction events. I expect that we're going to be seeing more stories like this.
NIELSEN: Debinsky studies the links between extinctions and climate changes. She says this paper doesn't prove that this particular snail was done in by global warming, but she wouldn't be surprised if that turned out to be true. That's partly because ecologists have been saying for years that the species most vulnerable to climate change are the ones trapped in isolated habitats, like small islands, or mountaintops, or wildlands surrounded by people. In those kinds of situations…
Dr. DEBINSKY: Organisms can't move as easily, and so if the world changes, they are pretty much stranded in these patches of habitat that they're in. Maybe they can't go across an interstate highway, maybe they can't go through an urban area, and so the climate that they like to move into is not accessible.
NIELSEN: In other words, if the globe continues to get warmer, what happened to the snail you probably never heard of could soon be happening all over the world.
John Nielsen, NPR News, Washington.
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