Climate change almost certainly lies behind the storms that have been lashing Britain this winter, according to the Met Office’s chief scientist.
Dame Julia Slingo said while there was not yet "definitive proof", "all the evidence" pointed to a role for the phenomenon.
She also delivered a grim warning that the country should prepare itself for more similar events in future.
The comments came at a briefing for journalists as the latest wave of storms crashed into southern England. It is the strongest link yet made by the Met Office between the intense weather and climate change, and backs David Cameron’s remark last month that he “very much suspects” a connection.
Persistent rain
New analysis published by the Met Office blames persistent rainfall over Indonesia and the tropical West Pacific for triggering the weather system.
“The severe weather in the UK coincided with exceptionally cold weather in Canada and the USA,” the document said. “These extreme weather events on both sides of the Atlantic were linked to a persistent pattern of perturbations to the jet stream over the Pacific Ocean and North America.
“There is a strong association with the stormy weather experienced in the UK during December and January and the up-stream perturbations to the jet stream over North America and the North Pacific.
“The North Atlantic jet stream has also been unusually strong; this can be linked to an unusually strong westerly phase of the stratospheric Quasi-biennial oscillation deep polar vortex and strong polar night jet.”
Dame Julia said none of the individual storms had been exceptional but the “clustering and persistence” were extremely unusual.
“We have seen exceptional weather. We cannot say it’s unprecedented, but it is certainly exceptional,” she said.
“Is it consistent with what we might expect from climate change? Of course, as yet there can be no definitive answer on the particular events that we have seen this winter, but if we look at the broader base of evidence then we see things that support the premise that climate change has been making a contribution.”
Recent studies have suggested storms are developing a more southerly track, and that has been “typical” of the weather patterns here over the winter.
“One of the most unusual aspects of the winter’s weather has been the southerly track of the storms. We expect them to go well north of Scotland,” Dame Julia said.
"They have been slamming into the southern part of Britain. We also know that the subtropical, tropical Atlantic is now quite a lot warmer than it was 50 years ago.
'Basic physics'
"The air that enters this storm system comes from that part of the Atlantic where it is obviously going to be warmer and carrying more moisture.
“This is just basic physics.
“We also now have strong evidence that extreme daily rainfall rates are becoming more intense. That is emerging in the UK records, and it is seen very definitely around the world in other countries like India and China.
“There is indeed as far as I can see no evidence to counter the premise that a warmer world will lead to more intense daily and hourly heavy rain events.”
Dame Julia said sea levels were expected to rise by a foot over time, causing more problems for those trying to deal with flooding. “That might not sound a lot, but when you are looking at storm surges, when you are looking at moving water from the Somerset Levels out to sea, it does matter,” she added.