Extreme rainfall events in Britain could become up to four times more frequent over 50 years due to climate change, a new study suggests.
Met Office researchers created a new climate model to project the increase based on global warming reaching 7.74°F (4.3°C) by 2100.
They also found that even with a smaller global temperature increase, it would still lead to nearly three times more heavy precipitation than today by the 2070s.
Experts say global warming is generally expected to intensify extreme rainfall globally, as warmer air can hold more moisture.
This heavy rainfall – defined by the study as 20 mm/h – is problematic because it can cause flash flooding, which causes water levels to rise rapidly and is particularly destructive.
Warning: Extreme rainfall in Britain could become up to four times more frequent in 50 years due to climate change, new Met Office study suggests (stock image)
Worrying trend: Researchers created a climate model to project the increase in extreme rainfall events in regions of Britain (pictured) based on global warming reaching 7.74°F in 2100. They compared the average number of such events in the 1980s to the 2070s
Recent examples of such events in the UK include flash floods in Birmingham in May 2018, which resulted in fatalities, and in London in July 2021.
The authors said an increase in extreme rainfall would pose a challenge to local communities trying to cope with future flooding.
EXTREME RAINFALL EVENTS: 1980 vs. 2070
|Northern Scotland||0.54||5:30 pm|
|North West England||0.78||3.95|
|Yorkshire and Humber||0.77||2.77|
|East of England||1.06||3.35|
|South West England||1.19||5.32|
|South East England||1.16||3.57|
In England alone, an estimated three million properties are at risk from surface water flooding.
For this reason, the team added, they hope their research will help inform policy decisions in infrastructure design, land management and investments in flood protection.
Professor Elizabeth Kendon, from the Met Office and the University of Bristol, teamed up with colleagues to create a model that would study local future hourly extreme rainfall events of more than 20mm/h in the UK, both in the 1980s as in projections for the 2070s.
They found that 40 years ago there were an average of 11.9 such events per year, while that is expected to rise to 49.2 in half a century.
In Wales alone, extreme rainfall exceeding 20mm/h is expected to increase from 1.54 in the 1980s to 5.80 in the 2070s.
The corresponding figures for the East of England are 1.06 to 3.35; Southwest 1.19 to 5.32; Southeast 1.16 to 3.57; Northeast 0.45 to 2.05; and Northwest 0.78 to 3.95.
Yorkshire and the Humber are predicted to have 2.77 such events per year through the 2070s, compared to 0.77 in the 1980s; West Midlands 2.27 and East Midlands 2.64.
Northern Ireland will not escape either, with projections rising to 3.21 from 0.53 40 years ago.
Northern Scotland goes from 0.54 to 5.30, the west from 0.67 to 4.42 and the east from 0.53 to 3.97.
Meanwhile, London is predicted to have 0.61 extreme rainfall per year through the 2070s, compared to 0.21 in the 1980s.
The authors wrote: ‘Regionally, future changes in the number of events will vary in excess of 20mm/hr, with the largest increases in the north of the UK.
“In Northern Scotland, for example, events are almost 10x more common in the 2070s than in the 1980s.”
These graphs show how the number of extreme rainfall events (the black line) is expected to increase with temperature rises across Britain
Flood risk: This graph shows the number of extreme rainfall events per year in the 1980s (left) versus the number predicted in the 2070s (right)
Their models show that ‘climate change leads to an average of 20 per cent more precipitation per hour in the UK and 40 per cent more regional registrations’.
In a high-emissions scenario, the researchers added, “the probability of extreme rainfall per hour will increase by about a factor of 4, which is significantly greater than suggested by previous generations of coarser-resolution climate models.”
“For every degree of regional warming, we see the intensity of extreme rainfall increasing by 5-15 per cent per hour and there are on average nearly nine more extreme events per year in the UK.
“Thus, changes in extreme rainfall events are expected to be pronounced even in medium to low emission scenarios.”
The new research is published in the journal Nature communication.
PAVING OVER FRONT GARDEN FOR CARS TO PARK ON COULD PUT RESIDENTIAL HOUSES INTO FLOOD RISK, EXPERTS WARN
Paving the front yard to make room for cars puts your home at high risk of flooding, experts warn.
A report from the National Infrastructure Commission (NIC) warns that 325,000 English homes are in high-risk flood zones, meaning they have at least a 60 percent chance of being flooded in the next 30 years.
It claims the proliferation of waterproof surfaces, such as paved gardens, could put an additional 65,000 properties in the high-risk category by 2055.
The NIC says around £12 billion in investment will be needed over the next 30 years to prevent 600,000 homes from flooding due to inadequate drainage.
The National Infrastructure Commission (NIC) has warned that 325,000 UK homes are in high-risk flood zones. Pictured: hull flooding in June 2007
The report calls for stricter planning regulations to ensure new construction homes can withstand heavy downpours by installing roof gardens, drainage ponds and rain gardens.
Computer projections suggest that 250,000 properties could be moved out of the high-risk category by better investment in drainage systems.
Professor Jim Hall, National Commissioner for Infrastructure, said: ‘It is clear that in the face of more intense rainfall and increasing urbanisation, we need to start taking this kind of flooding much more seriously.’
The report urges the government to tackle the unplanned spread of paved surfaces, force water companies to invest in drainage infrastructure and encourage the development of flood-resistant housing.
Experts believe that by 2072 gardens will have water sensors and flood barriers, while homes will be equipped with means of escape such as inflatable rafts.