Climate change: UK extreme rainfall events expected to be more frequent by the 2070s

Extreme local rainfall events in the UK may become up to four times more frequent by the 2070s under a high emission scenario, compared to current levels, according to new climate model simulations presented in Nature Communications. The findings could help support policy decisions in land management, infrastructure design, and investment in flood protection.

Recent floods across Europe have reinforced the need for a better understanding of how rainfall will change locally over the coming decades with global warming. Flooding in central Europe in July 2021 resulted in more than 200 fatalities and considerable damage to infrastructure, with estimated costs for Germany alone between €4.5–5.5 billion. Extreme precipitation is generally projected to intensify with global warming as warmer air has the capacity to hold more moisture. However, precipitation is a very localised event that is influenced by many factors, and is governed by climate variability. Therefore, how global warming will affect rainfall locally in the future remains unclear.

Elizabeth Kendon and colleagues used new climate model simulations to study local hourly rainfall extremes, exceeding 20 mm/h, in the UK. They found that extreme rainfall events are projected to become four times more frequent by the 2070s under a high emission scenario (in which warming is predicted to reach about 4.3 °C by 2100), while previous, lower resolution models projected a smaller increase of two–three times in this period. However, this increase is influenced by climate variability, which may result in the random occurrence of a cluster of record-breaking events, potentially followed by the absence of them even for multiple years. This tendency towards clustered extreme rainfall events poses challenges for local communities trying to adapt, and is therefore important to consider for planning and management, the authors suggest.