World's wildlife and environment already hit by climate change, major study shows
Pastor Dale Morgan
World's wildlife and environment already hit by climate change, major
study shows*
· 90% of damage caused by rising temperatures
· Conclusions based on reports going back to 1970
* Ian Sample, science correspondent
* The Guardian,
* 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 reports 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,
shifts 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
reports highlighting changes in populations or behaviour of 28,800
animal and plant species. They examined a further 829 reports that
focused on different environmental effects, including surging rivers,
retreating glaciers and shifting 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 shifts 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 reports examined by the team were published between 1970 and
2004, during which time global average temperatures rose by around 0.6C.
The latest report 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 shifts in water availability will have a big impact on
water management and be critical to securing supplies, the scientists say.
By collecting disparate reports 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 reports 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 shift, 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.