Climate change has already led to local extinctions in half of species surveyed in a new study — and global temperatures are only set to rise.
By Kate Wheeling
A sculpture of a polar bear and cub, afloat on a small iceberg, passes in front of the Houses of Parliament in London, England, in 2009. (Photo: Oli Scarff/Getty Images)
Climate change is quickly altering the face of the planet, increasing temperatures, changing precipitation patterns, and swallowing coastlines. But how species respond to those changes is hard to predict: some adapt, some move, but some will inevitably go extinct. Unfortunately, the latter of those three options is not uncommon: A new study finds that climate change has already caused localized extinctions in hundreds of species, which doesn’t bode well for their overall survival.
Most species are evolved to live in specific environmental niches, and researchers have long been studying how quickly species’ geographic ranges are changing in response to climate change. John Wiens, a professor of ecology and evolutionary biology at the University of Arizona, tapped into that bank of data in the new study, published today in PLoS Biology.
Wiens looked back at 27 studies covering hundreds of species for warm edge contractions — cases in which species’ ranges receded from regions where temperatures rose. The disappearance of a species from a portion of its former range amounted to a local extinction, according to Wiens.
The study found that local extinctions occurred in 47 percent of the 976 species evaluated. That number only reflects theclimate change that’s occurred so far — less than one degree Celsius increase in global temperatures between the late 19th century and 2012. But climate models project that the globe could warm by another one to four degrees by the end of the century.
“We’ve had this little bit of change so far, and, for a lot of populations, for about half these species, it was too much,” Wiens says. “It basically suggests that things don’t seem to be adapting quickly enough to survive.”
In other words, it’s not necessarily that species can’t change to live in a changing climate, but that climate change is outpacing their ability to adapt. And while many species may be leaving some environments and expanding into others, there are limits to how much a species’ range can shift; man-made structures may already occupy potential habitats, and many species, like those that live on islands, for example, have territories that are already bounded by natural barriers.
Wiens found that local extinctions were more common in animals than plants, and in tropical species than those living in temperate regions — evidence that climate change may be hitting the more biodiverse regions of the world hardest.
“These are sort of preliminary results that would suggest that there’s going to be a big loss of biodiversity from climate change,” Wiens says. “It’s a really terrible experiment that’s being played out.”