The Heat Is Online

Climate Change Will Outpace Animals' Ability to Find New Habitats

Most mammals won't flee climate change fast enough, May 15, 2012

As the climate changes over the next century, the ranges of nearly 90 percent of mammal species will shrink — in many cases because animals won't be able to get to areas where the climate is going to become suitable for them, says new research.

Across the Western Hemisphere, the study also found, nearly 10 percent of mammals will be unable to move fast enough to keep up with changes in climate. In some areas, such as the Amazon, that number will be as high as 40 percent.

And while some animals will do just fine or even better than before, certain animals in certain places face catastrophic losses of survivable habitat. Most at risk are primates, which will likely lose 75 percent of their range because of both inhospitable climate and the inability to get to livable places.

"We could be underestimating the vulnerability of some species to climate change," said Carrie Schloss, an ecologist at the University of Washington.

"There have been a lot of projections done on species' ranges and where they are projected to be in the future based on where the climate will be suitable," she added. "But most don't tell you whether species can get from where they are today to where the climate will be suitable." 

To make more accurate predictions of how mammals might be expected to fare in the coming decades, Schloss and colleagues collected information on 493 species of mammals whose future ranges had already been predicted through about the year 2100. Then, the researchers used known relationships between how big an animal is and what it eats to estimate how far a given species could be expected to move from generation to generation.

Previous studies have shown that climate change will expand the ranges where some species will be able to live. But when Schloss' team factored in whether animals could actually get to these newly suitable habitats, they found that true ranges will actually shrink in nearly 60 percent of those cases. Range size will shrink by an average of nearly 40 percent.

Animals in tropical regions face the biggest risks, the researchers report today in the Proceedings of the National Academy of Sciences, possibly because species there are extra-sensitive to even small changes in climate.

Across the moist subtropical regions of the western hemisphere, for example, nearly 15 percent of mammals will likely be left behind by climate change. That number jumps to nearly 40 percent in some areas of the Amazon. In those places, species that can only migrate about one kilometer (0.6 miles) each year would need to move eight times faster to keep up with climate-induced shifts in their ideal rangelands.

Other areas that are likely to experience climate changes that are more extreme than many species will be able to handle include the Yucatan Peninsula, the Appalachian Mountains and the southeastern United States. Primates are in particularly trouble, as are moles and shrews.

Animals expected to be able to keep up with climate change include carnivores, armadillos, sloths, coyotes, elk and moose. Many of these animals can move large enough distances to get them to where they'll need to go.

The new study should help researchers focus conservation efforts by, for example, figuring out where to create corridors for animals that will need to migrate in the face of climate change, said David Ackerly, an ecologist at the University of California, Berkeley.

"Unfortunately, there is not a lot of good news in analyses of climate impacts," he said. "Rapid change will be disruptive. The question is: Where will impacts be worse and what can we do?"