SLASHING the level of atmospheric pollution may actually accelerate climate change far beyond the worst-case scenario predicted by experts, according to a new study.

Scientists have demonstrated that particles of chemicals and dust in the atmosphere are helping to keep the earth cool, and that reducing pollution could take away the artificial protection which has built up over many years, sending global temperatures soaring.

The study comes two days after a report by the Benfield Hazard Research Centre predicted that the oceans could rise by as much as 84 metres over the next 200 years if nothing is done about climate change, turning the British mainland into a string of fragmented islands.

The new British and German study predicts that, by 2100, the planet is likely to be more than 6C warmer than it was in 1840. This compares with the forecast from the Intergovernmental Panel on Climate Change of a warming of between 2.3C and 4.9C since pre-industrial times.

No-one can predict what the effects of such rapid climate change are likely to be, the scientists said.

The team, led by Dr Meinrat Andreae, from the Max Planck Institute for Chemistry in Mainz, Germany, wrote in the journal Nature: "Such a degree of climate change is so far outside the range covered by our experience and scientific understanding that we cannot with any confidence predict the consequences for the earth system."

Soaring temperatures would be expected to wipe out many species of plants and animals that were unable to adapt quickly enough to the changing conditions. Other possible effects could be severe droughts and crop failures, violent storms due to the disruption of weather systems, and a rapid rise in sea levels that could swamp low-lying coastal communities.

The scientists pointed out that aerosols influence climate in a number of ways. The tiny particles intercept sunlight and reduce the amount of energy reaching the ground.

Aerosols produce many small water droplets in clouds, making them more reflective and contributing further to cooling. Smaller droplets are also less likely to coalesce and become heavy enough to fall as rain. This extends the lifetime of clouds, and, thereby, earth's reflectivity.

The scientists said the 21st-century climate was likely to suffer a "treble hit". There would be greater warming from greenhouse gases, reduced cooling from aerosols and an increased release of carbon due to soil decomposition.