"Certainly the message from the natural science side, the part of science that looks at how the climate system really works, isn't very good. There isn't any good news to be found there," Katherine Richardson, a scientist at the University of Copenhagen, which is hosting the talks, said.

'Catastrophe'

Climate scientists at the summit said that sea levels could rise by a metre - twice as much as previously projected 2100, if the melting of polar ice sheets continues.

"This means that if the emissions of greenhouse gases is not reduced quickly and substantially even the best-case scenario will hit low-lying coastal areas housing one-tenth of humans on the planet hard,'' organisers said in a statement.

John Church, of the Centre for Australian Weather and Climate Research ,said: "Unless we undertake urgent and significant mitigation actions, the climate could cross a threshold during the 21st century committing the world to a sea level rise of metres".

John Ashton, Britain's top climate negotiator, said nations needed to take such findings more seriously.

"We need a much stronger sense in our societies of urgency. We need to look at what is a 'reasonable worst case' in the lifetime of people alive today," he said.

"A sea level rise of one or two metres would not just be damaging for China, it would be an absolute catastrophe. And what is catastrophic for China is catastrophic for the world," he said.

Richardson said: "Most of us have been trained as scientists to not get our hands dirty by talking to politicians. But we now realise that what we are dealing with is so complicated and urgent that we have to help to make sure the results are understood."

She said the IPCC report was an invaluable document, but will be vastly out of date by the time policy makers convene in December to negotiate a global climate treaty.