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Global warming to bring heavier summer downpours

1 June 2014, by Alex Peel

Global warming could cause extreme summer downpours to become several times more frequent in the UK by 2100, a new study suggests.

Wind and rain

Its authors say this will likely lead to an increased risk of flash flooding, similar to the Boscastle floods of 2004 and the 'Toon Flood' in Newcastle in 2012.

While winter floods tend to be caused by prolonged and persistent spells of rainfall, summer floods tend to be 'flashier', caused by shorter, sharper downpours.

Scientists have already predicted wetter winters into the future, with UK summers expected to become drier overall. But as the atmosphere warms, it will be able to hold more moisture, potentially leading to more intense summer bursts of rainfall.

Until now, climate models have lacked the detail to reliably predict changes in intense rainfall. To overcome this hurdle, the scientists ran computer simulations at eight times the resolution of existing models - similar to those used to produce the 5-day weather forecast.

It required nine months of processing power on the Met Office supercomputer, one of the most powerful in the world, to run the simulations for just the southern half of the UK.

The experiment required nine months of processing power on the Met Office supercomputer – one of the most powerful computers in the world

'The very high resolution model used in this study allows us to examine these changes for the first time,' says Dr Lizzie Kendon from the UK Met Office, who led the study.

'It shows heavier summer downpours in the future, with almost five times more events exceeding 28 millimetres in one hour in the future than in the current climate - changes we might expect theoretically as the world warms.'

The simulations were run for two 13-year periods, one based on the current climate, and the other based on the expected climate around 2100.

Researchers say the results, published in the journal Nature Climate Change, are a first step towards building a more complete picture of how UK rainfall may change as the climate warms. They say the findings will need to be verified by other similarly detailed simulations elsewhere.

'The next steps are to see if these changes are consistent with observed trends in summer rainfall extremes and changes projected by climate models in other parts of the world,' says Prof Hayley Fowler, from Newcastle University, one of the study's co-authors.

'The first stage of this will be to run the same high-resolution simulation over the northern half of the UK.'

The study forms part of CONVEX, a three-and-a-half-year project funded by NERC and the Met Office to improve understanding of the causes and characteristics of extreme rainfall.

Kendon EJ, Roberts NM, Fowler HJ, Roberts MJ, Chan SC, Senior CA, 'Heavier Summer downpours with climate change revealed by weather forecast resolution model', Nature Climate Change, 2014.

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Your comments

Who's the fear mongering neocon again?
Prove the deniers wrong and find them one scientist that has ever "believed" beyond their laughable; "95%" certainty.
The planet is 100% not flat.

mememine69, Toronto
Sunday, 1 June 2014 - 21:21

Hang on, our local climate expert, Prof. Tim Flannery told us our dams would never be full again. This was just before we had so much rain that they all overflowed. We do we believe? Is this just more alarmist guessing?

R James, Australia
Monday, 2 June 2014 - 07:12

So far, the climate models have all been failures. None predicted the last 18 years of no warming. It looks to me like we have a long way to go before we can have any prediction of future climate. Even the most critical parameters, such as clouds, are poorly understood, as highlighted by the IPCC.

RJ, Australia
Monday, 2 June 2014 - 10:03

Just out of interest, what do neocons have to do with any of this? Have Richard Perle and Paul Wolfowitz gone into climate modelling or something?

Tom Marshall, Planet Earth Online
Monday, 2 June 2014 - 15:32

I think the more we screw with nature, the worse it will get, the more the human race tries to "undo" from our doing, we only make it worse. Now spraying these chemicals into our stratosphere is only going to poisen all life below, we are truly living in the tribulation times

Jeff, Detroit Michigan
Monday, 9 June 2014 - 02:08

Do people still fall for this hype. I thought everyone knew that its hyped up government bullshit to raise tax. We have had nothing to do with climate change and will have nothing to do with changing it. Get on with your life and pay your Green tax.

ed, london
Thursday, 28 August 2014 - 17:09

"We have had nothing to do with climate change and will have nothing to do with changing it."

People keep on saying that. Again and again and again. It'd be lovely if it was true; sadly the science overwhelmingly points the other way, and no amount of loud internet dogmatism is going to make much difference to that.

Tom Marshall, Planet Earth Online
Friday, 29 August 2014 - 16:53

"sadly the science overwhelmingly points the other way"
Hmm, is that the same science paid for by governments. Thought so.

ed, london
Friday, 29 August 2014 - 18:03

Governments would love for this problem to go away. Imposing unpopular short-term costs on people in exchange for benefits that won't be felt until years down the line, long after they've left office, doesn't generally fill politicians with joy. But despite that, they mostly accept climate change is happening. Because the science is all on one side, even if you'd prefer not to believe it. The same's even true of great swathes of the fossil fuel industry, which has an obvious incentive not to acknowledge there's a problem but nevertheless does so.

Tom Marshall, Planet Earth Online
Wednesday, 3 September 2014 - 17:41