Fears have been raised that the UK could soon see a repeat of the sort of flooding that has hit in recent years after forecasters predicted a one-in-three chance there would be a new record set for monthly rainfall during coming winters.
The Met Office used a supercomputer to simulate possible extreme weather conditions to help build up a picture of what was likely to befall the UK. Forecasters found a 7% chance of a monthly rainfall record being set in the south-east. This rose to 34% once other regions of England and Wales were taken into account.
“Our analysis showed that these events could happen at any time and it’s likely we will see record monthly rainfall in one of our UK regions in the next few years,” said Dr Vikki Thompson, the lead author of a report published in the journal Nature Communications.
Since the sort of extreme conditions being studied are relatively rare, the team needed more than the data they could get from observed records.
Prof Adam Scaife, who leads this area of research at the Met Office, said a new supercomputer was used to simulate thousands of possible winters, “some of them much more extreme than we’ve yet witnessed. This gave many more extreme events than have happened in the real world, helping us work out how severe things could get.”
The results demonstrated the likelihood of “one or more monthly regional rainfall record events” in a given winter, the Met Office said. It added that its method could also be “applied to assess other risks such as heatwaves, droughts, and cold spells and could help policymakers, contingency planners and insurers plan for future events”.
Severe rainfall has caused widespread flooding in the UK in recent years; notably in the north-west of England in the winter of 2015-16 and in the south-east in 2013-14. Cleanup costs in the Thames Valley alone on that occasion were estimated to be more than £1bn.
Richard Allan, professor of climate science and joint head of the department of meteorology at the University of Reading, said exceptional seasonal rainfall in the UK was the result of a “perfect storm” of atmospheric influences.
“Using serious number crunching power, the new study plays back thousands of possible weather patterns that emerge from detailed computer simulations of recent decades, some of which produce more extreme rainfall events than have actually been experienced to date.
“The work complements evidence that warming of climate is already causing extreme rainfall events to intensify.
“As the planet continues to warm due to human-caused greenhouse gas emissions, extra moisture in the air will fuel increasingly intense rainfall causing a continued rise in the risk of damaging events into the future.”
His colleague, Prof Len Shaffrey, from the university’s National Centre for Atmospheric Science, added: “Using weather and climate models to better understand the probability of extreme weather is an important method that is becoming more widely used to help inform those dealing with weather impacts about the risks of extreme events.
“Future research needs to evaluate how well weather and climate models are able to accurately simulate other extreme weather events, for example droughts and heatwaves, if we want to use models to better understand extreme weather risks and how they might be changing.”
