Climate: UK study eyes links between global warming, extreme flooding

An extratropical cyclone
An extratropical cyclone spread heavy rain across the UK in February 2014. Visit this NASA website for more.

More coastal damage likely as rising seas fuel storm surges

Staff Report

FRISCO —British scientists aren’t quite ready to say that last winter’s record flooding is linked with human-caused global warming, but in a recent study published in the journal Nature Climate Change, they warned that more coastal flooding is likely as sea level rises.

“We saw a number of examples last winter that demonstrated the vulnerability of coastal regions to flooding from surge events,” said Dr. Jason Lowe, of the UK Met Office. “At present our best evidence points towards future increases in coastal flooding being driven by global sea-level rise. We still need to better understand if changes in atmospheric storminess can also play a part.”

The review was led by scientists at the Centre for Ecology & Hydrology, in collaboration with the Met Office and the Universities of Oxford, Exeter and Reading.

“The challenge is to understand in full the subtle balances between the competing influences on UK winter weather, whether they are from the oceans, the amount of polar sea ice, or the atmospheric state itself,” said lead author, Dr Chris Huntingford, with the Centre for Ecology & Hydrology.

“Highly refined modelling techniques are now emerging that can tease apart often large natural fluctuations in these drivers from any effects of increasing atmospheric carbon dioxide concentrations,” Huntingford said.

This study did not find a link between dwindling Arctic sea ice and UK weather patterns, but other research has suggested that the loss of ice in high latitudes is changing the path of the jet stream in ways that can result in more extreme weather.

“The continual advance in scientific understanding of how the climate system operates implies that we will soon be able to assess better if there is any likelihood of the rainfall patterns of last winter occurring with altered frequency,” he said.

“The winter flooding was exceptional for its geographical extent and, particularly, its longevity … the duration of the floodplain inundations created rarely experienced disruption for the affected communities, transport and agriculture,” said co-author Terry Marsh, with the Centre for Ecology & Hydrology.

“Last winter was the wettest winter in England and Wales since such measurements began in 1766,” said co-author Dr Peter Stott, of the Met Office. “Detailed climate monitoring carried out at the National Climate Information Centre at the Met Office shows that large parts of southern England and central Scotland had more than 170 percent of the average winter rainfall for 1981-2010,” Stott said.

“This new review shows how a complex chain of events involving the Pacific Ocean and an unusual jet stream led up to this unprecedented winter. More work is needed to robustly detect any changes in storminess in the UK and quantify how the risk of such extreme winters varies with climate variability and change, Stott said. “However climate models of sufficient resolution to capture storms and their associated rainfall are now becoming available and need to be deployed as soon as possible to provide a solid evidence base for future investments in flood and coastal defenses.”



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