"This study provides even stronger scientific
evidence that global warming will result in catastrophic
species loss across the planet," said Jay Malcolm, an
assistant forestry professor at the University of Toronto
and a lead author of the study with scientists in the United
States and Australia.
Last month, a U.N. study said humans were responsible for
the worst spate of extinctions since the dinosaurs and urged
unprecedented extra efforts to reach a U.N. target of
slowing the rate of losses by 2010.
Scientists disagree about how far global warming is to blame
compared with other human threats such as deforestation,
pollution and the introduction of alien species to new
The new study looked at 25 "hotspots"--areas that contain a
big concentration of plants and animals--and projected that
11.6 percent of all species, with a range from 1 percent to
43 percent, could be driven to extinction if levels of heat
trapping-gases in the atmosphere were to keep rising in the
next 100 years.
The range would mean the loss of thousands, or tens of
thousands, of species. The report gave a wide range because
of uncertainties, for instance, about the ability of animals
or plants to move toward the poles if the climate warmed.
"Areas particularly vulnerable to climate change include the
tropical Andes, the Cape Floristic region (on the tip of
South Africa), southwest Australia, and the Atlantic forests
of Brazil, Paraguay and Argentina," it said.
Species in many of these regions have limited escape routes.
Rare plants, antelopes, tortoises or birds found only on the
southern tip of Africa, for instance, cannot move south
because the nearest land is thousands of miles away in
The scientists said their study broadly backed the findings
of a 2004 report in the journal Nature that suggested global
warming could commit a quarter of the world's species to
extinction by 2050. No one knows how many species are on
earth, with estimates ranging from 5 million to 100 million.
"It isn't just polar bears and penguins that we must worry
about any more," said Lee Hannah, co-author of the study and
senior fellow for climate change at Conservation
International in the United States.
"We used a completely different set of methods (from the
Nature study) and came up with similar results. All the
evidence shows that there is a very serious problem," he
Global warming is widely blamed on rising concentrations of
carbon dioxide in the atmosphere linked to emissions of
gases from burning fossil fuels in cars, factories and power
The U.N.'s Kyoto Protocol obliges about 40 nations to cut
emissions by at least 5.2 percent below 1990 levels by 2008
President Bush pulled the United States out in 2001, arguing
that Kyoto was too costly and wrongly excluded poor nations.
Bush instead favors big investments in new technology to
break what he has called a U.S. addiction to oil..