World's wildlife and environment already hit by climate change, major study
shows
· 90% of damage caused by rising temperatures
· Conclusions based on re****ts going back to 1970
a.. Ian Sample, science correspondent
a.. The Guardian,
a.. Thursday May 15 2008
Global warming is disrupting wildlife and the environment on every
continent, according to an unprecedented study that reveals the extent to
which climate change is already affecting the world's ecosystems.
Scientists examined published re****ts dating back to 1970 and found that
at
least 90% of environmental damage and disruption around the world could be
explained by rising temperatures driven by human activity.
Big falls in Antarctic penguin populations, fewer fish in African lakes,
****fts in American river flows and earlier flowering and bird migrations
in
Europe are all likely to be driven by global warming, the study found.
The team of experts, including members of the UN's intergovernmental panel
on climate change (IPCC) from America, Europe, Australia and China, is the
first to formally link some of the most dramatic changes to the world's
wildlife and habitats with human-induced climate change.
In the study, which appears in the journal Nature, researchers analysed
re****ts highlighting changes in populations or behaviour of 28,800 animal
and plant species. They examined a further 829 re****ts that focused on
different environmental effects, including surging rivers, retreating
glaciers and ****fting forests, across the seven continents.
To work out how much - or if at all - global warming played a role, the
scientists next checked historical records to see what impact natural
variations in local climate, deforestation and changes in land use might
have on the ecosystems and species that live there.
In 90% of cases the ****fts in wildlife behaviour and populations could
only
be explained by global warming, while 95% of environmental changes, such
as
melting permafrost, retreating glaciers and changes in river flows were
consistent with rising temperatures.
"When we look at all these impacts together, it is clear they are across
continents and endemic. We're getting a sense that climate change is
already
changing the way the world works," said lead author Cynthia Rosenzweig,
head
of the climate impacts group at Nasa's Goddard Institute for Space Studies
in New York.
Most of the re****ts examined by the team were published between 1970 and
2004, during which time global average temperatures rose by around 0.6C.
The
latest re****t from the IPCC suggests the world is likely to warm between
2C
and 6C by the end of the century.
"When you look at a map of the world and see where these changes are
already
happening, and how many species and systems are already responding to
climate change after only a 0.6C rise, it just heightens our concerns for
the future," Rosenzweig said. "It's clear we have to adapt to climate
change
as well as try to mitigate it. It's real and it's happening now."
A large number of the studies included in the team's analysis reveal stark
changes in water availability as the world gets warmer. In many regions
snow
and ice melts earlier in the year, driving up spring water levels in
rivers
and lakes, with droughts following in the summer. Understanding ****fts in
water availability will have a big impact on water management and be
critical to securing supplies, the scientists say.
By collecting disparate re****ts on wildlife and ecosystems, it is possible
to see how disruption to one part of the environment has knock-on effects
elsewhere. In one study rising temperatures caused sea ice in Antarctica
to
vanish, prompting an 85% fall in the krill population. A separate study
found that the population of Emperor penguins, which feed on krill in the
same region, had also fallen by 50% during one warm winter.
A loss of krill, also a dietary staple for whales and seals, was cited as
a
factor in recent accounts of cannibalism among polar bears in the Arctic.
In
2006 Steven Amstrup, a world expert in polar bears at the US Geological
Society, investigated three cases of the animals preying on one another in
the southern Beaufort sea. A lack of their usual prey may have prompted
the
bears to turn on each other.
Other re****ts show how the early arrival of spring in Europe has
far-reaching effects down the food chain. The warmer weather causes trees
to
unfurl their leaves earlier, which causes a rise in leaf-eating grub
numbers
sooner in the year. Blue tits that feed on the grubs have largely adapted
to
the ****ft, by giving birth to their young two weeks earlier.
"It was a real challenge to separate the influence of human-caused
temperature increases from natural climate variations or other confounding
factors, such as land-use changes or pollution," said David Karoly, a
co-author based at Melbourne University in Australia.
http://www.guardian.co.uk/environment/2008/may/15/climatechange.scienceofclimatechange?gusrc=rss&feed=networkfront
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