Manmade global warming evident on every continent, polar report finds

Data compiled by the University of East Anglia finds evidence of warming in Antarctica that can for the first time be directly attributed to human emissions
David Adam, environment correspondent
guardian.co.uk,
Thursday October 30 2008 18.01 GMT

Melting ice in the polar regions will have a major impact on future sea levels. Photograph: John McConnico/AP
No corner of the Earth is immune from the effects of global warming, according to a new study that confirms manmade temperature rises in both the Arctic and Antarctic regions. Temperature records over the last century show that warming in the planet's coldest and most remote wildernesses is caused by human emissions of greenhouse gases.
The study, published today in Nature Geoscience, is the first to find the fingerprints of manmade global warming on the Antarctic, where a shortage of data makes it hard to be sure. Last year's report, from the Intergovernmental Panel on Climate Change (IPCC), said human influence could be detected on every continent, except Antarctica. Climate sceptics have exploited this omission to question the science of global warming.
In the new study, Nathan Gillett, then working at the Climatic Research Unit at the University of East Anglia, though now at Environment Canada, compiled, with colleagues, climate data across the Arctic and Antarctic regions since 1900, and compared the patterns with those produced by computer simulations with and without human activity.
They say only the models that included human influences – such as emissions of carbon dioxide and chlorofluorocarbons (CFCs) – were able to reproduce the observed temperature trends.
Gillett said: "The main message is that for the first time we are able to directly attribute warming in both the Arctic and Antarctica to human influence. Melting of ice shelves has implications for sea-level rises."
Peter Stott, head of climate monitoring and attribution at the Met Office, who worked on the study, said: "In both polar regions, the observed warming can only be reproduced in our models by including human influences, natural forces alone are not enough.
For a long time climate scientists have known that Arctic areas would be expected to warm most strongly because of feedback mechanisms. But the results from this work demonstrate the part man has already played in the significant warming that we've observed in both polar regions."
The polar regions have seen some of the most dramatic impacts of climate change on the planet in recent years. The Arctic is warming twice as fast as the global average, which has contributed to record melting of sea ice in the Arctic summer and thinning in the winter.
The picture in Antarctica is more complex, but the rocky Antarctic peninsula has experienced temperature rises of 3C over the past 50 years – among the largest recorded. Other parts, including the vast east-Antarctic ice sheet, have seen less change.