Number of days without rain to increase by end of 21st century

Researchers at Scripps Institution of Oceanography, UC San Diego suggest that by the end of the 21st century, some parts of the world can expect as many as 30 more days a year without precipitation.

Ongoing climate change caused by human influences will alter the nature of how rain and snow falls; areas that are prone to dry conditions will receive their precipitation in narrower windows of time.

Computer model projections of future conditions analyzed by the Scripps team indicate that regions such as the Amazon, Central America, Indonesia, and all Mediterranean climate regions around the world will likely see the greatest increase in the number of "dry days" per year, going without rain for as many as 30 days more every year.

California, with its Mediterranean climate, is likely to have five to ten more dry days per year.

This analysis advances a trend in climate science to understand climate change on the level of daily weather and on finer geographic scales.

Study lead author Suraj Polade, a postdoctoral researcher at Scripps, said that one of the implications of this finding is that annual rainfall could become less reliable in drying regions as annual averages will be calculated over a smaller number of days. The 28 models used by the team showed agreement in many parts of the world on the change in the number of dry days those regions will receive.

The study appears in Scientific Reports, the open-access journal from Nature Publishing Group.