BRITAIN:Greenhouse gas emissions from human activity are causing global shifts in rainfall patterns and contributing to wetter weather over Europe, climate scientists report.
Their study is the first to find a "human fingerprint" in the rainfall changes that have been detected in a belt of the northern hemisphere stretching from the Mediterranean to Norway.
The results, based on a global comparison of weather records going back to 1925, suggest that levels of rainfall across Britain have increased steadily by an average of 6.2mm every decade.
At least half of the extra rainfall and possibly up to 85 per cent is caused by the impact of greenhouse gas emissions, the scientists conclude.
The research, carried out by the Hadley Centre of the British Meteorological Office with several national climate research centres, does not prove that any single episode of extreme wet weather can be directly linked to climate change, but it supports the idea of a long-term rise in rainfall linked to emissions.
The study, published in the journal Nature, adds weight to the growing belief that Britain is experiencing a fundamental shift in weather pattern with bursts of extremely hot conditions and almost tropical downpours.
In central England as waters of the Severn, Avon and Thames continue to rise, the British Environment Agency described conditions in the region as the "worst floods in modern times".
Prime minister Gordon Brown, who flew over the flood region yesterday, used his first monthly press conference since taking office to make the clear link between global warming and the flood devastation.
The study compared records from weather stations with predictions from 10 computer models of global climate. Some models included the effects of human-induced climate change while others took into account only natural changes or more exotic factors such as volcanoes and the sun's activity.
Only models factoring in human-induced climate change could adequately explain the observed rainfall changes, the scientists found.
"The paper is saying there is a significant human influence on global rainfall patterns," said Dr Peter Stott at the Hadley Centre.
"The study looks at the trends in annual precipitation, but we don't address the trickier issue of what is happening with the extreme events.
"Especially regionally, that is harder to discern because there is much more variability and the events are rarer as well, so it is a more difficult problem."
Apart from the increase in rain in northern high latitudes - the belt between 40 and 70 degrees north that includes Ireland and Britain - the analysis found climate change brought wetter conditions in the southern tropics and subtropics. It also found a link between global warming and drier conditions in the northern tropics and subtropics.
"This is a very important paper," said Dr Myles Allen of Oxford University.
He said the paper identified for the first time "the fingerprint of human influence" and that the precipitation trends "may be harbingers of more to come".
In Britain and Ireland , the long-term forecast is for wetter winters and drier summers.
"The really difficult one to figure out is that even under drier summers you might get more extreme events," Dr Stott said.
Chris Huntingford of the Centre for Ecology and Hydrology said such studies could prepare governments for dangerous climate change.
"It has now been confirmed that the burning of fossil fuels has altered rainfall patterns at the global scale," he said. "Next we need to understand how these observed large-scale adjustments translate to local changes in extreme rainfall events.
"These highly regionalised estimates of rainfall will be essential in aiding governments to prepare for what might, in some circumstances, represent dangerous climate change."