The three-day conference starting on Tuesday takes place in the run-up to the implementation on 16 February of the UN's Kyoto Protocol, the greenhouse-gas pact that has triggered fierce tensions between Europe and the US.

 

The forum Avoiding Dangerous Climate Change, has been called by British Prime Minister Tony Blair, who as current president of the Group of Eight (G8) nations, is lobbying the US to do more to tackle climate change.

 

It is the biggest scientific convention on greenhouse gases since the publication in 2001 of a report by the UN's top expert group, the Intergovernmental Panel on Climate Change (IPCC).

 

That landmark document blew away any last doubts among mainstream scientists that carbon pollution, spewed out by burning oil, gas and coal, could alter the world's delicate climate system.

 

The report was, however, hedged with uncertainties. The panel admitted that it lacked a clear picture as to how quickly and how badly the climate system would be affected.

 

Giant strides

 

Since then, however, climate science and computer power have made giant strides. The point behind the Exeter meeting is to share the latest discoveries as well as the latest data on questions that were poorly understood four years ago.

 

A study suggests some of Europe
may return to the Ice Age

But there are also likely to be admissions that, in some key areas, knowledge remains frustratingly scant.

 

More than three dozen papers are to be presented in Exeter, and they will be synthesised in a set of conclusions that will be submitted to the G8.

 

"However, it will not have any recommendations for policymakers," conference chairman Dennis Tirpak said last week.

 

The studies range from highly technical reports on improving computer models to predictions about the impact of climate change on crops, biodiversity and disease.

 

Ice Age again?

 

At the apocalyptic extreme is a risk assessment of a shutdown of the Gulf Stream, a current which originates in the tropical western Atlantic and bathes the coastline of Western Europe.

 

If the stream were stopped, or even significantly slowed, by a rush of melting freshwater from the Greenland ice-sheet, Western Europe would plunge back into the Ice Age. 

 

The 2001 IPCC Third Assessment report - next to be updated in 2007 - calculated that, by 2100, temperatures would rise by between 1.4C and 5.8C compared to 1990 levels.

 

The range depends on atmospheric concentrations of carbon dioxide, a gas which traps the sun's heat like a greenhouse, and causes the Earth's surface to warm.

 

The Kyoto Protocol requires industrialised signatories - excluding the US, which says the deal is too costly for its oil-dependent economy - to trim output of six greenhouse gases by a deadline of 2008-2012.

 

But scientists say this effort is puny compared to what is needed if we want to avert climate change that could be potentially catastrophic and long-lasting.