Tue, Sep 29, 2009 - Page 6 News List

Warming a threat in our lifetimes: report

THE GUARDIAN , LONDON

Unchecked global warming could bring a severe temperature rise of 4ºC within many people’s lifetimes, a new report for the British government said.

The study, prepared for the Department of Energy and Climate Change by scientists at the Met Office (the UK’s national weather service), challenges the assumption that severe warming will be a threat only for future generations, and warns that a catastrophic 4ºC rise in temperature could happen by 2060 without strong action on emissions.

Officials from some 190 countries were to gather in Bangkok yesterday to continue negotiations on a new global deal to tackle global warming, which they aim to secure at UN talks in December in Copenhagen.

“We’ve always talked about these very severe impacts only affecting future generations, but people alive today could live to see a 4ºC rise,” said Richard Betts, the head of climate impacts at the Met Office Hadley Center, who will announce the findings today at a conference at Oxford University. “People will say it’s an extreme scenario, and it is an extreme scenario, but it’s also a plausible scenario.”

Scientists said a 4ºC rise over pre-industrial levels could threaten the water supply of half the world’s population, wipe out up to half of animal and plant species, and swamp low-lying coastlines.

A 4ºC average would mask more severe local impacts: the Arctic and parts of Africa could see warming up to 10ºC, the report said.

The study updates the findings of the 2007 report of the Intergovernmental Panel on Climate Change (IPCC), which said the world would probably warm by 4ºC by 2100 if greenhouse gas emissions continue to rise. The IPCC also listed a more severe scenario, with emissions and temperatures rising further because of more intensive fossil fuel burning, but this was not considered realistic.

“That scenario was downplayed at the time because we were more conservative a few years ago,” Betts said.

A report from the UN Environment Program last week said emissions since 2000 have risen faster than even this IPCC worst-case scenario.

“Created in the 1990s, these scenarios all assumed political will or other phenomena would have brought about the reduction in greenhouse gas emissions by this point,” Betts said. “In fact, CO² emissions from fossil-fuel burning and industrial processes have been accelerating on a global scale.”

The Met Office scientists used new versions of the computer models used to set the IPCC predictions, updated to include carbon feedbacks. Often called tipping-points, these feedbacks occur when warmer temperatures release more carbon, such as from soils.

When they ran the models for the most extreme IPCC emissions scenario, they found a 4ºC rise could come by 2060 or 2070, depending on the strength of the feedbacks.

“It’s important to stress it’s not a doomsday scenario, we do have time to stop it happening if we cut greenhouse gas emissions soon,” Betts said.

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