for National Geographic News
A new study suggests that global warming could threaten one-fourth of the world's plant and vertebrate animal species with extinction by 2050.
The report's authors reached their conclusion after estimating potential changes to habitatsand the resulting loss of speciesin 25 biodiversity "hot spots" around the world.
The ecologically rich hot spots include South Africa's Cape Floristic Region, the Caribbean Basin, and the tropical regions of the Andes Mountains. These territories compose only a small fraction of the planet's land area but contain large numbers of Earth's flora and fauna.
"These [hot spots] are the crown jewels of the planet's biodiversity," lead author Jay Malcolm of the University of Toronto told the Canadian Press.
"Unless we get our act together soon, we're looking at committing ourselves to this kind of thing."
The report appears in the current issue of the journal Conservation Biology.
Many Threats Seen
Global warming projections are by nature uncertain, and the report includes many variables that significantly affect species' survival rates both for good and for ill.
Changes to the rate and degree of warming, as well as the ability of species to migrate or adapt, altered the estimates of species' extinction risk.
Climate change is also only one threat to species diversity. Many plants and animals are already feeling the effects of habitat destruction and invasions by non-native species. It is difficult for scientists to take all such factors into account.
Still, the study's worst-case scenarios are sobering.
They include a doubling of present carbon dioxide levels (as predicted by many climatologists) and rising temperatures that could potentially eliminate 56,000 plant and 3,700 animal species in the 25 hot spot regions.
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