A new study has examined how high-impact weather within the UK, like extremely hot days, heavy rainfall and really cold conditions, might be affected at different levels of worldwide warming.

The study, published within the journal Climatic Change, found that the upper the extent of worldwide warming, the projected increase in frequency or severity or both are going to be stronger for decent weather, droughts and flooding within the UK. These high-impact weather events can cause significant disruption across the united kingdom affecting sectors like health, transport, agriculture and energy.

Key findings from the paper include:
The number of extremely hot days within the UK could increase four-fold
Currently days exceeding 25.0°C could rise from around 10 days a year now (range 8-11 days) to 37 days (range 32-46 days with a 4.0°C rise in heating .
With a 2.0°C rise in average global temperature the amount of days exceeding 25.0°C is calculated to be 18 days per annum . Posing increasing risk to human health from extreme heat.

The number of days of high-impact heavy rainfall within the UK resulting in severe weather warnings could rise by three days per annum
Currently, there are around 7 days per annum (range 6-9 days) in England and Wales with intense and prolonged rainfall that would cause river flooding. With a 4.0°C rise in global temperature this might rise to 11 days per annum (range 10-13 days).
Under a 2.0°C rise in global temperature it’s expected England and Wales will receive 9 days (range 8-10 days) of intense and prolonged rainfall.

The number of days when temperatures fall below 0.0C are likely to subsided frequent
Currently there are around 50 days (range 45-56 days per year) where temperatures dip below 0.0°C annually within the UK.
In a world that has increased to 4.0°C, the united kingdom would expect to record 12 days (range 9-21 days) per annum .
With a 2.0°C rise we’d expect to ascertain around 34 days (range 27-44 days) per annum .

More frequency and severe long-term droughts, with droughts a minimum of as severe as seen in 2010 increasing by 146%, at a 4.0°C level of worldwide warming and 86% more frequent by 2.0°C.
Lead author Dr Helen Hanlon, said: “Our research clearly shows that the more we warm the earth through human-induced global climate change , the more severe weather we will expect within the UK. Severe weather can impact us during a number of the way , from our health, to flooding, food availability and transport issues.

“Importantly, the paper shows that the rise in high-impact weather is reduced if heating is kept as low as possible, showing that efforts to scale back human-induced global climate change will curb the foremost severe impacts of future weather within the UK.”

With changes evident at even 1.5°C of worldwide warming this is often a reminder that even with the foremost optimistic global emissions mitigation scenarios there’s still a requirement for adaptation, long-term planning and risk assessment activities across sectors within the UK.

The authors used simulations from the united kingdom CP18 12km high resolution ‘Regional Climate Model’ and located that the UK can expect a rise of hot days (where temperatures exceed 25°C), with a minimum of 5 additional hot days per annum at a 1.5°C level of worldwide warming and up to 39 additional hot days per annum at a 4.0°C level of worldwide warming. This increase in frequency, future summers are projected to become hotter, and adaptation are going to be more important to mitigate risk to human heat from extreme heat.

An increase of high-impact rainfall days is additionally projected, with a minimum of 1 additional day per annum at a 1.5°C level of warming and up to eight additional days per annum at a 4.0°C level of worldwide warming. Suggesting more frequent river flooding having widespread severe impacts across the united kingdom .

As well as severe rain, the united kingdom can expect a rise within the frequency and severity of long-term droughts, with droughts a minimum of as severe as seen in 2010 increasing by 146%, at a 4.0°C level of worldwide warming. 2010 is within the top 10% of driest years within the UK since 1862. Adaptation of water management practices can expect to be required to deal with increased severity of drought.

The likelihood of cold conditions is additionally impacted, with a minimum of 10 fewer days per annum where temperatures fall below 0.0°C at a 1.5°C level of warming, and up to 49 fewer days per annum at a 4.0°C level of warming. this is able to mean less cold-weather disruption thanks to less than normal chance of ice and snow.

The research has recently been comprehensively cited within the UK’s third global climate change Risk Assessment (CCRA3), compiled by the global climate change Committee. the danger Assessment technical report makes frequent use of the findings from this research.

As well as causing future impacts, human-induced global climate change has already influenced extreme weather within the UK. Research has shown global climate change made the 2018 record-breaking UK summer temperatures about 30 times more likely than it might be naturally. Additionally, a separate study found that extreme heavy rainfall just like the record rainfall observed on 3 October 2020 would during a natural environment, with no influence from human-induced global climate change , be a 1-in-300-year event, it’s now a 1-in-100-year event within the current climate.

Professor Jason Lowe OBE, said: “This study provides a part of the image for what our future weather and climate may appear as if . Crucially it sits alongside other studies, like those examining the risks from wildfire and floods, helping to make as full a vision of the longer term as possible. The more insight we’ve on our future world, the more opportunity there’s to plan for it.”

Funding for this work was supported by the Met Office Hadley Centre Climate Programme funded by BEIS and Defra, also because the UK Climate Resilience Programme led jointly by the Met Office and UK Research and Innovation (UKRI) under the Strategic Priorities Fund. The UKRI programme is co-delivered by Met Office and NERC on behalf of the UKRI partners AHRC, EPSRC and ESRC.