Extreme precipitation over land has increased over both the wettest and driest regions of the world, and is likely to keep intensifying through the twenty-first century, reports a paper published online this week in Nature Climate Change. The study has key implications for dry regions, which may be unprepared for the potential related flooding.

Global warming is expected to intensify the hydrological cycle, following a ‘wet get wetter, dry get drier’ trend. However, it has not been clear whether this pattern will apply over land areas or how different aspects of rainfall - total precipitation or extreme precipitation - will vary regionally.

Markus Donat and colleagues examine global changes in total and extreme precipitation over different climatological areas, focusing on wet and dry regions. Using observations and models, they found that daily precipitation extremes have increased by about 1-2% per decade across both kinds of regions since 1950, with climate projections showing this trend is expected to continue until at least the end of the twenty-first century. They suggest that this is directly related to the increased atmospheric moisture content associated with warmer temperatures. The authors conclude that adaptation measures for more extreme rainfall are needed on a global scale and that this is particularly urgent in dry regions, which are not prepared for such events.

In an accompanying News & Views article, William Ingram writes: “Given the intrinsic rarity of extreme events, these results do not tell us what will actually happen in any particular location, but rather how risks will change - which is precisely the information needed by emergency planners.”