UK ‘will be wetter than climate predictions, increasing flooding in coming decades’

Hilly regions of the UK could in future receive at least half a metre more rainfall than climate experts are predicting by the middle of the century, increasing flood risks to towns and cities, researchers say.

But the extra water could have surprising benefits – boosting capture of damaging carbon from the atmosphere and providing more food for wading birds, according to the scientists.

The academics found that national climate models underestimate the downpours the UK is likely to get in spring, summer and autumn in the coming decades, with upland areas in particular due to receive more than forecast.

They looked at rainfall records from the 1870s to the present day and compared them with climate change predictions the Met Office produced last year.

The Met Office’s Climate Projections 2018 (UKCP18) report was billed as the “most comprehensive picture yet of how the climate could change” in the UK.

But the new findings suggest there could be “a large divergence by the mid-to-late 21st century” in rainfall, with the “observed mismatch” greatest in upland areas.

The research, at Plymouth University and published in Climate Research, focused on Dartmoor and Plymouth but the scientists believe it applies nationwide.

Paul Lunt, associate professor in environmental science and one of the study’s authors, told The Independent that on present trends, rainfall each year at uplands sites with the longest records would rise by nearly a quarter - 24 per cent - by 2070-2099.

"This would be an increase in annual rainfall from a present day annual average at our Dartmoor sites of 2,250mm rainfall to 2,790mm - an increase in annual rainfall of 540mm or over half a metre."​

The extra rainfall would be likely to cause more flooding in lowlands, particularly in towns and cities, where rivers tend to meet, he said.

“There’s likely to be more flooding, when farmers can’t get into their fields to harvest their crops, which rot,” he said.

“But for wading birds such as plover and snipe that require uplands to breed there potentially will be more food such as invertebrates in aquatic pools in the wet peat.

“So for biodiversity and CO2 it’s good news: carbon dioxide accumulates in peatlands, and wetlands systems need water."

“Upland areas are among the most important UK regions in terms of biodiversity and carbon sequestration, but they are also the most vulnerable to increased precipitation,” Dr Lunt added.

Upland areas, those more than 300m above sea level, cover around a third of the UK’s land area, are considered of national and international importance because of their biodiversity and cultural heritage, he said.

They also supply more than two-thirds of the UK’s fresh water and have a significant role in flood risk mitigation.

Levels of rainfall in the uplands are typically twice the average of those for UK lowland sites. The results show that over the past 130 years rainfall in upland areas has increased in all seasons, with spring, autumn and winter increasing by more than 12 per cent.

The researchers also found that summer rainfall on Dartmoor is not falling, contrary to Met Office predictions that by 2050 it will decrease by up to 20 per cent.