How may extreme weather change in the future?

Aim: To show how we can assess whether the severity and frequency of extreme weather may change in the future. This work would incorporate a range of UKCP09 future climate projections and a statistical method known as extreme value analysis (EVA).

What are extreme events?

These are high impact events which happen infrequently. They are regularly described in terms of how often they are likely to happen, for example a 'one in 30 year flooding event' means it will happen on average once every 30 years. There are many industries (insurance, transport, local authorities) which must take these events into consideration, due to the damage and disruption they can cause. 

What information will UKCP09 provide?

UKCP09 provides estimates of how the following elements will change in the future:

  • Temperature of the coolest day/night
  • Temperature of the warmest day/night
  • Rainfall on the wettest day

How can Extreme Value Analysis (EVA) help?

We can use EVA, together with regional climate computer models, to assess how the frequency and severity of extreme events may change in the future. This information can be used when planning future infrastructure - for example ensuring adequate drainage on roads or future proofing public buildings to withstand increased hot spells.

In the examples below, we have calculated the amount of rain (mm) that falls for a 1 in 30 year event for 1960-1991 left-hand plot), 2070-2090 (right-hand plot) and the difference (bottom plot).  For the UK, the simulations project the amount of rainfall for a 1 in 30 year event will increase by between 1 and 15 mm (on average), but for parts of western Scotland, England and Wales, this increase could be as much as 30 to 40 mm.

The amount of precipitation (mm) that falls for a 1 in 30 event (low emissions) The amount of precipitation (mm) that falls for a 1 in 30 event (low emissions) The amount of precipitation (mm) that falls for a 1 in 30 event (medium emissions) The amount of precipitation (mm) that falls for a 1 in 30 event (medium emissions)

The amount of precipitation (mm) that falls for a 1 in 30 event The amount of precipitation (mm) that falls for a 1 in 30 event (high emissions)

Last updated: 11 May 2011