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Scientists Divided Over UK Flooding

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Oliver Moody, Paul Simons and David Brown, The Times

Scientists are divided over whether the profusion of extreme weather that has hit Britain over the past few years is a product of climate change or natural variation.

This is the decade of records. The 15.9in of rain dumped on Thirlmere in Cumbria over the past two days — the heaviest 48-hour fall noted in this country — is only the latest in a carnival of meteorological freaks. In a striking visual symbol of these extraordinary times, torrents have cascaded over Melham Cove in the Yorkshire Dales for the first time in living memory as the landmark became the largest unbroken waterfall in England.

Scientists are divided over whether the profusion of extreme weather that has hit Britain over the past few years is a product of climate change or natural variation. The question is not just academic: for the civil servants tasked with marshalling the country’s flood defences, it is a matter of life and death.

Dame Julia Slingo, chief scientist at the Met Office, skirted controversy yesterday by claiming that “all the evidence” pointed to climate change as a factor behind Storm Desmond.

“As with the stormy winter of two years ago, the evidence from fundamental physics and our understanding of our weather systems suggests there may be a link between climate change and record-breaking winter rainfall,” she said.

The storm that has visited so much violence on northern Britain since Friday is certainly an artefact of global unrest. Storm Desmond arose out of an atmospheric river of subtropical moisture travelling some 4,300 miles across the Atlantic from Florida.

On the other side of the world, the stirrings of the most powerful El Niño on record may be driving more storms in the our direction. “El Niño doesn’t explain why Cumbria was deluged, but it does raise the chances of more storminess,” said Jeff Knight, a forecaster at the Met Office’s Hadley Centre. […]

Some scientists are worried that the agency may be stuck in its ways. Patrick McSharry, head of forecasting and risk analysis at the University of Oxford’s Smith School of Enterprise and the Environment, said the government had not adapted well to the increasing number of sudden surges of rain.

“My guess is the EA has not taken account of the tendency of extreme weather events to cluster and that the estimation of return periods is based on traditional extreme weather statistics, using as long a historical record as can be accessed,” he said.

Dr McSharry and his colleagues warned in 2010 of a significant rise in the number of intense bursts of rainfall hitting northwest Britain. […]

Thorsten Wagener, professor of water and environmental engineering at the University of Bristol, said that it was simply too hard to know how much to factor in climate change and other shifts when calculating flood risk.

“While there are indications that we see increasing extreme rainfall events in the UK, it is difficult to know how much of this change results from climate change,” he said.

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