Senior climate scientists are linking global warming to the UK Met Office's announcement yesterday (3 January) that 2012 was England’s rainiest year since records began.
The weather service's numbers showed that due to slightly more seasonal figures in Wales and Scotland, the UK as a whole experienced its second wettest summer recorded.
But four of the UK’s Top Five wettest years have now occurred since 2000, a statistic in line with the expectations of climatologists who model the effects of a warming world.
“It is not just Britain but many other parts of northern Europe and north America that are getting wetter and there is a climate change component to it,” Kevin Trenberth told EurActiv over a phone line from the US National Center for Atmospheric Research in Boulder, Colorado.
Trenberth has won several awards for his scientific research, including the Nobel Peace Prize which he was co-awarded in 2007 for his work as lead author on the UN Intergovernmental Panel on Climate Change (IPCC)’s fourth risk assessment report.
“The overall pattern has been that middle to high latitudes [have] an increase in precipitation that goes with a warming climate, and the fact that the air can hold more moisture so the hydrological cycle speeds up,” he said.
Increased moisture in the air can also fuel super storms like Hurricane Sandy, in the view of Trenberth and many other scientists, even if such effects can be difficult to predict.
“A global intensification of intense rainfall events is a very robust expectation with climate change,” said Gabriele Hegerl, an expert in the influence of climate change on precipitation at Edinburgh University.
Hegerl, who is also an IPCC author, told EurActiv that the phenomenon had already been observed on a global basis.
Although there was some uncertainty about the increased variability in downpours and floods, recorded increases in heavy precipitation “can be attributed to greenhouse gases and anthropomorphic climate change,” she said.
8,000 homes and businesses flooded
According to the Met Office’s figures, at least 8,000 British homes and businesses were flooded in 2012, a year which saw 1337.3 mm of rain overall, just 6.6 mm shy of the record set in 2000.
The Met Office said that its preliminary research suggested that the character of this rainfall was changing too, with severe downpours becoming more frequent over time.
“The trend towards more extreme rainfall events is one we are seeing around the world, in countries such as India and China, and now potentially here in the UK,” said Professor Julia Slingo, the chief scientist at the Met Office.
“Much more research is needed to understand more about the causes and potential implications,” she added. In the 30-year periods between 1961-1990 and 1981-2010, annual UK rainfall increased by around 5%.
Climate modeling suggests that this trend will increase across the planet, although rainfall levels will vary widely.
Sudden and severe downpours
Greenhouse gases can stabilise the atmosphere as well as warming and moistening it, leading to more sudden and severe downpours from clouds heavy with water.
“If you draw a line around the globe starting with the UK, this whole region is expected to become wetter,” Hegerl said, “the wet regions become wetter and the dry regions drier.”
“We’re foreseeing a range of changes that will make the Mediterranean particularly vulnerable to becoming more dry,” she added.
As well as Europe’s dry region moving north, when the North Atlantic Oscillation – which brings rain to Scandinavia and northern Europe – is high, winter storm systems tend to move into northern Europe and not the Mediterranean.
Yet despite the increasing evidence of changing and often extreme weather patterns, scientists say they are increasingly concerned at a lack of urgency among policy makers in tackling the problem.
“It seems like the policy has been to grin and bear it and suffer the consequences,” Trenberth said. “Certainly there is no planning to mitigate these events and reduce the odds of their happening again in the future.”
“It is very disappointing and extremely short-sighted,” he said.
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