Global warming will become a top cause of extinction from the
tropical Andes to South Africa with thousands of species of plants and
animals likely to be wiped out in coming decades, a study said on
Tuesday.

"Global warming ranks among the most serious threats to
the planet’s biodiversity and, under some scenarios, may rival or
exceed that due to deforestation," according to the study in the
journal Conservation Biology.

"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 UN study said humans were responsible for the worst spate of
extinctions since the dinosaurs and urged unprecedented extra efforts
to reach a UN 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 habitats.

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 1-43 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.

NO ESCAPE

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 Antarctica.

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 5-100 million.

By Alister Doyle
Reuters.com