Climate Change Killed This Critter, but Can Others Be Saved From Extinction?
Australian scientists were “devastated” in 2014 when they visited the tiny island home of the Bramble Cay melomys, the Great Barrier Reef’s only endemic mammal, and found no one home. They described it as probably “the first recorded mammalian extinction due to anthropogenic climate change."
What really hurt was that they were visiting the island on a rescue mission, to find enough individuals for a captive breeding project. The ambition was to rebuild the population and reestablish it in some more hospitable habitat. They were too late: Repeated storm surges had wiped out the plant that was the major food source for the melomys, and the last few members of the species, the product of a million years of evolution, were probably swept out to sea and drowned.
That painful example has many conservationists thinking hard about what they call “assisted colonization.” That is, they are wondering whether and how to move species to places they have never lived before—because that may be their only chance to survive the climate change regimen of warmer temperatures, rising seas, and extreme weather events like drought, flooding, and wildfire.
One of the first such assisted colonizations happened this past August, also in Australia, where a team of researchers loaded up their vehicles with captive-bred specimens of the critically endangered western swamp tortoise and drove them three hours south. Their old home near the city of Perth in Western Australia was rapidly drying out in the face of persistent drought. Researchers had to sort through 13,000 potential sites to find one that would still feel like a swamp in the drier climate 50 years from now—and where the newcomer wouldn’t displace existing species. It’s too soon to know whether that experiment will succeed—or even whether the remaining tortoises will go extinct in their old habitat.
Yet the pressure to think about such relocations before another melomys-style extinction is everywhere in conservation. A study this year predicted that about 30 percent of all terrestrial mammals will be unable to expand their range fast enough to keep pace with climate change. Even highly mobile species like birds and butterflies lag behind the pace of change. Housing, highways, and other human developments often aggravate this “migration lag” by breaking up potential migratory routes.
Assisted colonization is, however, a fiercely debated alternative, with critics describing such efforts as “planned invasions” and a game of “ecological roulette.” They fear that relocated species may cause extinctions or a host of other unintended consequences in their new habitat, as introduced species have often done.
Most conservationists share those concerns. They’ve spent much of their careers dealing with the consequences of species invasions. Their psychology has traditionally been geared to restoring habitats, not reinventing them. Imagining how habitats might look and where species can expect to survive in some unknown future is a terrifying endeavor.
Their answer so far has been to approach the idea cautiously, with guidelines and decision trees to help sort out the questions: What can I do to keep the species going for now, and what will it take in 30 years? At what point does it make sense to attempt a translocation? What do I need to know about the ecology of the species involved? What other species does it depend on, and are they also susceptible to movement? Since it will be impossible to save all the species threatened by climate change, how do we decide which species matter enough to us or to the environment for us to undertake the enormous effort translocation will entail?
“It’s really about value judgments, but value judgments are part of any decision,” said Tracy Rout, a research fellow at the University of Queensland and a creator of one recent algorithm for translocation decision making. “We need to say what’s important, what are the things we care about. You do that even if you’re just trying to decide whether to take an umbrella to work. You’re thinking about the weather, but also how big is my umbrella? How annoying is it to carry it around? Do I have an important meeting? Do I have to walk far? Am I going to be carrying my computer and not want it to get wet? Your values are there, and you need a framework to put them in perspective.”
Not so long ago, conservation biology was about trying to put together a jigsaw puzzle—a natural habitat with all its old diversity. That was hard enough, with some of the pieces not just missing but extinct. Now it’s as all of us have kicked the jigsaw puzzle into the sky, and the trick for biologists is to put it together again while it is not just airborne but caught in the shifting winds of climate change.
Also it’s starting to rain. So did you bring your umbrella? Or, wait, maybe it will never rain again. And here is a species you care about passionately. Maybe it's some lizardy thing, or an insect, or even a snake, but you care as if it were a big-eyed puppy at the pound with no time left and nobody else to take it home. So here are the five things you could do to make the difference between survival and oblivion. Only one of them will save the day. It’s not an emotional decision, but time is running out: Choose.