Writing in the journal Nature, analysts at the Potsdam Institute for Climate Impacts Research in Germany say a rise of at least 3C by 2100 is likely.

The team also says many countries, including EU members and China, have pledged slower carbon curbs than they have been achieving anyway.

They say a new global deal is needed if deeper cuts are to materialise.

"There's a big mismatch between the ambitious goal, which is 2C... and the emissions reductions," said Potsdam's Malte Meinshausen. "The pledged emissions reductions are in most cases very unambitious," he told BBC News.

In their Nature article, the team uses stronger language, describing the pledges as "paltry".

"The prospects for limiting global warming to 2C - or even to 1.5C, as more than 100 nations demand - are in dire peril," they conclude.

Between now and 2020, global emissions are likely to rise by 10-20%, they calculate, and the chances of passing 3C by 2100 are greater than 50%.

According to the Intergovernmental Panel on Climate Change (IPCC), this implies a range of serious impacts for the world, including

• significant falls in crop yields across most of the world
• damage to most coral reefs
• likely disruption to water supplies for hundreds of millions of people.

(BBC News)

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