Global Warming
Will Kill Off
One Million Species
By Steve Connor
Independent
08 January 2004
A quarter of known land animals and plants,
more than a million species, will eventually die out because of the
global warming that will take place over the next 50 years, the most
important study of its kind has concluded.
International scientists
from eight countries have warned that, based even on the most conservative
estimates, rising temperatures will trigger a global mass extinction
of unprecedented proportions.
They said global
warming will set in train a far bigger threat to terrestrial species
than previously realised, at least on a par with the already well-documented
destruction of natural habitats around the world.
It is the first
time such a powerful assessment has been made and its conclusions will
shock even those environmentalists accustomed to "worst-case"
scenarios.
Professor Chris
Thomas, a conservation biologist from Leeds University who led the research
team, said only the "immediate" switch to green technologies
and the active removal of carbon dioxide from the atmosphere could avert
ecological disaster. "It will be a surprise to a lot of people,"
he said. "For some years scientists have said climate change may
lead to some extinctions but until now there's been no numerical analysis
of how big this is likely to be. We had no idea of whether it would
lead to the extinction of a few species or a really substantial number.
This study suggests the latter and it's extremely worrying.
"If the projections
can be extrapolated globally, and to other groups of land animals and
plants, our analyses suggest that much more than a million species could
be threatened with extinction as a result of climate change."
The study, in the
journal Nature, investigated 1,103 species of plants, mammals, birds,
reptiles, frogs, butterflies and other insects living in six areas -
Europe, South Africa, Australia, Brazil, Mexico and Costa Rica.
The scientists calculated
the effect of rising temperatures on each species using the three future
scenarios proposed by the UN's intergovernmental panel on climate change
(IPCC) which has predicted minimum, mid-range and maximum global average
temperature increases of between 0.5C to 3C by 2050.
Based on the knowledge
of the relatively gradual onset and aftermath of an ice age - and of
the past 30 years of dramatically rising temperatures - the scientists
were able to assess whether the expected climate change would result
in a species shifting to a cooler region, or not.
A warmer world would
push most species towards the poles or higher up mountains but for many
this would be impossible. The home territories of those that could move
might be so reduced as to make a breeding population unviable.
The study found:
* Of Australia's
more than 400 butterfly species, of which nearly 200 are unique to the
continent, all but three might not survive in the present home ranges.
More than half could be wiped out.
* Brazil's unique
savannah grassland the Cerrado faces disaster with some 45 per cent
of the endemic plants - some 2,000 species - facing extinction.
* In Europe, the
study predicts a 25 per cent extinction rate for birds under the maximum
temperature scenario of the IPCC.
* In Mexico's Chihuahuan
desert, extinction would be particularly high because threatened species
would have to travel long distances to reach cooler climates.
* In South Africa's
Cape Floristic region, the scientists believe between 30 and 40 per
cent of the Proteaceae, a family of flowering plants that includes South
Africa's national flower, the king protea, will die.
* In Costa Rica's
Monteverde cloud forests, warmer temperatures would increase the altitude
at which clouds form and even prevent their formation.
Lee Hannah, a senior
fellow at the Centre for Applied Biodiversity Science at Conservation
International in Washington DC, said the combination of habitat loss
and global warming would mean that there would be no safe havens even
for some of the most-protected species.
"This study
makes it clear that climate change is the most significant new threat
for extinctions this century," Dr Hannah said. "The combination
of increasing habitat loss, already recognised as the largest single
threat to species, and climate change, is likely to devastate the ability
of species to move and survive."