New realities of our warming world

LONDON (AFP) - A huge expanse of western Siberia is going through an unprecedented thaw that could speed the rate of global warming dramatically, a British weekly said.

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Scientists recently back from the Russian region say the world's largest frozen peat bog is melting into shallow lakes. It is thawing for the first time since it formed 11,000 years ago.

The area, a million square kilometres, is equivalent to the size of France and Germany and could release billions of tonnes of methane, a greenhouse gas, into the atmosphere, the New Scientist said on its website.

The discovery was made by Judith Marquand from Britain's University of Oxford and botanist Sergei Kirpotin from Russia's Tomsk State University.

Kirpotin described the situation as an "ecological landslide that is probably irreversible and is undoubtedly connected to climatic warming".

The whole western Siberian sub-Arctic region has started to thaw, he added, and this "has all happened in the last three or four years".

Climate scientists were worried by the discovery and warned future global temperature predictions may have to be revised.

"When you start messing around with these natural systems, you can end up in situations where it's unstoppable. There are no brakes you can apply," David Viner, a senior scientist at the Climatic Research Unit at Britain's University of East Anglia, told The Guardian newspaper.

"This is a big deal because you can't put the permafrost back once it's gone. The causal effect is human activity and it will ramp up temperatures even more than our emissions are doing," he told the British daily's Thursday edition.

The intergovernmental panel on climate change thought in its last major report in 2001 that global temperatures would rise between 1.4 degrees Celsius and 5.8 degrees Celsius between 1990 and 2100.

However, that only considered global warming sparked by known greenhouse gas emissions.

"These positive feedbacks with landmasses weren't known about then. They had no idea how much they would add to global warming," Viner said.