Climate projections show extreme UK’s weather will become even more extreme

“The UK’s set of climate projections are the best window we have on how climate change is likely to affect us out to the end of the century,” said Professor Jason Lowe OBE*, the lead for UKCP – the UK’s climate projections.

The latest iteration of climate projections for the UK were released in 2018, updating the set from 2009. In the early days of climate projections, users were able to examine features such as the expected rise in average temperature for a given location at a particular time of year. “But users also need an understanding of what extremes of weather will be like: What will be the maximum temperature in summer? Or how much rain will fall in the heaviest rainfall events,” added Professor Lowe. Being able to interrogate the data in this way is exceedingly important for a whole range of user groups, from the rail industry to water companies and from town planners to the energy sector.

In 2019 there was a programme of additions , including a rollout of a new set of projections which examine climate extremes on a grid of 2.2km. This provides new capability to resolve the fine detail of weather extremes and predict events such as flash flooding, based on new capability to resolve the dynamics of thunderstorms.

In addition to more local detail, information is needed on uncertainties associated with future extremes, in order to support assessments of risks at the city-scale, for example. Later this week the Met Office will be releasing a further update which will add new probabilistic projections on the hottest and wettest weather extremes. Dr Simon Brown, who led this extension, explains: “This work provides a range of plausible outcomes for rare events expected on average once every 20, 50 and 100 years, for a range of emissions scenarios. This will allow planners to weigh the risk of different outcomes against the costs of adaptation.”

Exeter temperature extremes

One -in-twenty year temperature extremes for Exeter. Black line is the median value.

Ahead of the release of the data for the whole of the UK, the Met Office has released information for Exeter which shows the impact that climate change could be expected to have on the city.

Currently, in Exeter there is around a one-in-twenty chance of the city recording daily maximum temperatures exceeding 33.0 C, in a given summer. However the figures show that even with a mid-range scenario of greenhouse gas emissions (RCP4.5), this value would be more likely than not to exceed 35.0 C by 2090, while maximum temperatures of over 40.0 C cannot be completely ruled out.

The figures for rainfall extremes are also higher in the future than now. Currently, there is a likelihood that in one winter out of twenty the city will see a single day with over 45mm of rainfall, but by 2090 the same figure is nearly 50mm; around a 10 per cent increase of rainfall on the heaviest day for rain in winter. The projections show that values of around 60mm cannot be ruled out completely.

Professor Jason Lowe

Professor Jason Lowe OBE

More information about UKCP is available on the Met Office’s Weather Snap podcast.


This entry was posted in Met Office News and tagged , , , , , , . Bookmark the permalink.