"We don't want to over-extrapolate in our findings, but if they hold, it's quite a scary thing to contemplate," said Timothy Benton, a co-author and professor of population ecology at the University of Leeds.
Beyond the Paper?
The study resists speculation about the present phase of global warming or humankind's possible role in it. It also notes that periods when species died out were often followed by a stabilization—a time when new species would appear.
"You might make a case for the possibility that climate warming could lead to a smaller increase in diversity than you otherwise might have expected," Foote said. "But there was no clear evidence that it would lead to a decrease in diversity."
In interviews, both Mayhew and Benton went beyond the more cautious terms of their paper, saying man-made global warming was accelerating the process.
"The issue here is that we are creating the climate change, and we are creating the climate change at an unprecedented rate," said Benton. "So clearly we are creating the events for a climate-related mass extinction that wouldn't otherwise be happening."
Those statements echo other controversial ideas. The International Panel on Climate Change, which recently shared the (Nobel Peace Prize with former U.S. Vice President Al Gore, has warned of a possible drop in biodiversity if temperatures rise by three or four degrees.
And last year, experts from 13 countries wrote an article in the journal Nature saying that climate change could push 37 percent of all species to extinction within the next 50 years.
"We are on the verge of a major biodiversity crisis," that letter said. "Virtually all aspects of diversity are in steep decline and a large number of populations and species are likely to become extinct this century.
Other scientists contend that these ideas are flawed or exaggerated.
Richard A. Muller, a physics professor at the University of California, Berkeley, published a controversial piece in Nature in 2005 suggesting a link between changes in climate and changes in biodiversity.
He believes that global warming will devastate the environment, but stopped well short of linking human-made global warming to biodiversity loss. He also said Mayhew and Benton had gone beyond the science of their paper.
"You can't make wild predictions if you can't justify them," Muller said. "If global warming continues at the current pace, I think we will have a tragic future. I think there will be great disruption, but whether humans affect biodiversity in a negative way, I don't think anyone ever really knows."
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