Unchecked global warming could bring a severe temperature rise of 4C within many people's lifetimes, according to a new report for the British government that significantly raises the stakes over climate change.
The study, prepared for the Department of Energy and Climate Change by scientists at the Met Office, challenges the assumption that severe warming will be a threat only for future generations, and warns that a catastrophic 4C rise in temperature could happen by 2060 without strong action on emissions.
Officials from 190 countries gather today in Bangkok to continue negotiations on a new deal to tackle global warming, which they aim to secure at United Nations 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 4C rise," said Richard Betts, the head of climate impacts at the Met Office Hadley Centre, 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."
According to scientists, a 4C 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 coasts.
A 4C average would mask more severe local impacts: the Arctic and western and southern Africa could experience warming up to 10C, the Met Office report warns.
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 4C 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 because we were more conservative a few years ago. But the way we are going, the most severe scenario is looking more plausible," Betts said.
A report last week from the UN Environment Programme said emissions since 2000 have risen faster than even this IPCC worst-case scenario. "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. In fact, CO2 emissions from fossil-fuel burning and industrial processes have been accelerating."
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