A sweeping new analysis enlisting scientists from 14 laboratories around the globe found that more than one-third of 1,103 native species they studied could vanish or plunge to near extinction by 2050 as climate change turns plains into deserts or alters forests.
Among the already threatened species that could go extinct are Australia's Boyd's forest dragon, Europe's azure-winged magpie and Mexico's Jico deer mouse.
The researchers concede there are many uncertainties in both climate forecasts and the computer models they used to forecast future extinctions. But they said their dire conclusions may well come to pass if industrial nations do not curtail emissions of greenhouse gases that trap heat in the atmosphere.
"We're already seeing biological communities respond very rapidly to climate warming," said Chris Thomas, a conservation biologist at the University of Leeds in England, and the study's lead author.
The findings by Thomas and 18 other researchers appear in Thursday's issue of the journal Nature.
Other scientists said the conclusions should prompt conservationists to begin weighing the impact of rapid, wide-ranging climate change as they assess the future of species, particularly those already in trouble.
Alastair Fitter, a University of York ecologist who was not involved in the research, said today's chief extinction culprits are deforestation and the impact of invasive species. Climate change will only hasten the demise of some species, he said.
"I think this is going to be third horseman in that particular apocalypse," said Fitter, who has documented how global warming is forcing some spring flowers to bloom increasingly early in Britain.
In the Nature study, researchers assessed the current habitat and distribution of 1,103 plant and animal species spread across six regions that included Mexico, Australia, Brazil, South Africa and Europe.
They applied climate change models developed by a United Nations panel that predicts Earth's current warming trend will increase average global temperatures by 2.5 degrees to 10.4 degrees Fahrenheit by 2100.
Depending on the temperature increase, the researchers found that 15 to 37 percent of the studied species will either go extinct or be on the road to extinction by 2050.
A mid-range forecast of three possible global warming scenarios would claim about a quarter of the species, they found.
Earth is home to an estimated 14 million plant and animal species, a tiny fraction of which — about 12,000 — conservationists estimate are threatened with extinction, although thousands of others are likely on the brink as well.
Terry L. Root, a senior fellow at Stanford's Institute for International Studies, said the findings show the need to link wildlife preserves so that threatened plants and animals can move to more favorable areas as warming changes the climate. Preserves are often divided by cities, highways or deforested tracts.
Lee Hannah of Conservational International, a co-author of the paper, said it may be shortsighted to simply set aside a preserve to protect a particular species but allow the destruction of surrounding habitat. "We may find in the future that species will only find suitable climatic conditions somewhere else," he said.