Global warming study warns of vanishing climates
Pastor Dale Morgan
Global warming study warns of vanishing climates*
· Scientists warn of disaster in biodiversity hotspots
· Species 'must evolve or migrate' to survive
James Randerson, science correspondent
Tuesday March 27, 2007
The Guardian
By the end of the century up to two fifths of the land surface of the
Earth will have a hotter climate unlike anything that currently exists,
according to a study that predicts the effects of global warming on
local and regional climates. And in the worst case scenario, the
climatic conditions on another 48% of the land surface will no longer
exist on the planet at all.
The changes - which will have a devastating affect on biodiversity
hotspots such as the Amazonian and Indonesian rainforests - will wipe
out numerous species that are unable to move to stay within their
preferred climate range. These species will either have to evolve
rapidly or die out.
"There is a real problem for conservation biologists," said the lead
author, John Williams, at the University of Wisconsin in Madison. "How
do you conserve the biological diversity of these entire systems if the
physical environment is changing and potentially disappearing?"
Studies already suggest that the ranges of species are shifting towards
the poles at around six kilometres a decade, but what will happen when
the rate of change intensifies?
His team used emissions scenarios set out by the Intergovernmental Panel
on Climate Change (IPCC) - the international scientific group that
advises policymakers - to predict where changes in temperature and
precipitation will occur.
As is already happening, the analysis predicts that as the planet warms
climate zones will move north and south towards the poles. To work out
the significance of these changes, the team compared them with the
climate variation that occurs naturally. They attach greater weight to
changes in regions that are relatively stable. This suggests that some
of the worst impacts will happen in tropical and subtropical regions as
they shift to new climatic conditions not currently seen.
"That's one of the things that really surprised us," said Professor
Williams. "The tropics have very little variability from year to year in
temperature, they are a very stable climatic zone. So species that live
in those climates expect a limited degree of variability." Other studies
have suggested that the Amazon basin, an extremely biologically rich
region, will be at increased risk of forest fires because of its hotter
and dryer climate.
"One of the things that comes from our paper is that because the species
that live in the tropics are adapted or have evolved for a reduced range
of variability, it may be that a two to three degree temperature change
in the tropics may be more significant than say a five to eight degree
change in high latitudes," he added.
Up to now, much of the focus of the impact of global warming has been on
polar regions because this is where the climate is changing fastest." At
the other end of the scale are climatic regions that will be lost from
the planet altogether.
The climate model predicts that these disappearing climates will be lost
mainly from tropical mountains and the edges of continents nearest the
poles.
As the Earth warms, these climate regions simply have nowhere to shift
to. Some of the losers are the tropical Andes, the African Rift
mountains, the Zambian and Angolan highlands, the South African Cape
region, south-east Australia, parts of the Himalayas and the Arctic.
The team reports in Proceedings of the National Academy of Sciences that
by 2100, between 12% and 39% of the land surface of the Earth will have
a new climate, while the combination of climatic conditions on 10%-48%
of the planet will have disappeared altogether. This is using one of the
IPCC's business-as-usual global development scenarios. Using a different
scenario that assumes more environmentally friendly development, the
corresponding predictions are 4% to 20%.
The true effect on species may be more than these numbers suggest,
though, because even if a climate still exists somewhere, it is no use
unless a species can migrate fast enough to follow it as it shifts. One
study published in 2004 predicted that 15% to 37% of species could be
driven extinct between now and 2050 assuming moderate climate warming.
Globally, this would mean the loss of more than 1 million species.