A Warming World Means a World Without Animals

A new study finds that the rate of extinction will accelerate with every increase in temperature, potentially wiping out one in six species.

The American pika faces an 80 to 100 percent risk of extinction if temperatures continue to rise, according to a new study. (Photo: Donald M. Jones/Getty Images)

Apr 30, 2015· 2 MIN READ
John R. Platt covers the environment, wildlife, and technology and for TakePart, Scientific American, Audubon, and other publications.

Climate change is a speed demon. And speed kills.

Conservationists and scientists have long predicted that climate change would push species around the world into extinction. Now comes word that the problem may be even worse than was previously realized. According to a paper published Thursday in the journal Science, the rate of extinction will dramatically speed up for every degree temperatures rise.

“If we follow through the business as usual in terms of greenhouse gas emissions, then we get to the point where one in six species are threatened with extinction from climate change,” said the paper’s author, Mark Urban, an evolutionary biologist at the University of Connecticut.

Urban’s research analyzed more than 130 previously published papers covering how climate change and other factors, such as habitat loss, will affect species extinctions. The previous papers covered certain groups of species or specific geographic ranges but didn’t look at the planet as a whole. By conducting a meta-analysis of that earlier research, Urban said he was able to come up with an “an overall picture of extinction risk.”

Urban said he expected to find that climate change would be one of the major factors affecting species extinctions in the coming decades, but he was surprised to find out how quickly that risk would accelerate.

According to his calculations, 2.8 percent of the world’s species are currently predicted to go extinct under current conditions. If global temperatures rise 2 degrees Celsius, that risk will increase to 5.2 percent. If temperatures rise one more degree, the risk balloons to 8.5 percent.

And if we continue on our current trajectory, in which global temperatures are anticipated to rise 4.3 degrees Celsius, Urban calculated that the risk increases even more, to the point where 16 percent of the world’s species will go extinct.

Urban said his analysis illustrates that climate change will pose many dangers beyond the ones we talk about the most, such as sea-level rise and drought. “There’s another impact, and that’s on our biodiversity,” he said.

The risk that species face will vary around the world according to their habitats. Species in North America and Europe, Urban found, will face a 5 percent and 6 percent risk of extinction, respectively.

That risk leaps upward in areas with greater levels of native biodiversity. Australia and New Zealand will each lose 14 percent of their species, Urban calculated.

South America will be hit hardest—23 percent of the continent’s unique species will go extinct if the rate of climate change does not slow.

Outside of specific regions, species with limited ranges or a limited ability to move to new habitats will also face a higher extinction risk. These include amphibians and lizards, as well as many plants, insects, and mammals.

“One example is the American pika,” Urban said. The species lives on mountains in very specific temperature ranges. Moving upward as ground temperatures rise shrinks their available habitat and food. They can’t move down the mountain or cross the plains to another mountain because they die if they get too warm.

Urban found that for many species with limited ability to adapt to new habitats, the risk of extinction ranges from 80 to 100 percent.

Even with this meta-analysis, Urban found that more data will provide an even better picture of the future. Particularly needed is more information about species in Asia and how climate change will affect that region, he said.

More information is also required about species that have not been fully studied, as well as how climate change will affect specific regions. He said that will help us “to pinpoint those species like the American pika that are most at risk and then try to implement conservation strategies to protect the most at-risk species.”

Urban said this study should be a wake-up call for the international community to take climate change’s effect on wildlife seriously.

“Biodiversity is the foundation of our economy, our future, our health, and our food security,” he said.