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Monday, May 26, 2008

Wildlife, environment hit by climate change

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 per cent 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.

Historical records

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 per cent of cases the shifts in wildlife behaviour and populations could only be explained by global warming, while 95 per cent 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 0.6 degrees C.

“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 0.6 degrees C rise, it just heightens our concerns for the future,” Rosenzweig said.

A large number of the studies 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 per cent 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 per cent during one warm winter.



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