for National Geographic News
By 2050, rising temperatures exacerbated by human-induced belches of carbon dioxide and other greenhouse gases could send more than a million of Earth's land-dwelling plants and animals down the road to extinction, according to a recent study.
"Climate change now represents at least as great a threat to the number of species surviving on Earth as habitat-destruction and modification," said Chris Thomas, a conservation biologist at the University of Leeds in the United Kingdom.
Thomas is the lead author of the study published earlier this year in the science journal Nature. His co-authors included 18 scientists from around the world, making this the largest collaboration of its type.
Townsend Peterson, an evolutionary biologist at the University of Kansas in Lawrence and one of the study's co-authors, said the paper allows scientists for the first time to "get a grip" on the impact of climate change as far as natural systems are concerned.
"A lot of us are in this to start to get a handle on what we are talking about," he said. "When we talk about the difference between half a percent and one percent of carbon dioxide emissions what does that mean?"
The researchers worked independently in six biodiversity-rich regions around the world, from Australia to South Africa, plugging field data on species distribution and regional climate into computer models that simulated the ways species' ranges are expected to move in response to temperature and climate changes.
"We later met and decided to pool results to produce a more globally relevant look at the issue," said Lee Hannah, a climate change biologist with Conservation International's Center for Applied Biodiversity Science in Washington, D.C.
According to the researchers' collective results, the predicted range of climate change by 2050 will place 15 to 35 percent of the 1,103 species studied at risk of extinction. The numbers are expected to hold up when extrapolated globally, potentially dooming more than a million species.
"These are first-pass estimates, but they put the problem in the right ballpark I expect more detailed studies to refine these numbers and to add data for additional regions, but not to change the general import of these findings," said Hannah.
Writing in an accompanying commentary to the study in Nature, J. Alan Pounds of the Monteverde Cloud Forest Reserve in Costa Rica, and Robert Puschendorf, a biologist at the University of Costa Rica, say these estimates "might be optimistic."
As global warming interacts with other factors such as habitat-destruction, invasive species, and the build up of carbon dioxide in the landscape, the risk of extinction increases even further, they say.
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