Climate change is already causing extremes in rainfall around the world, even in arid regions. The findings could mean a lot more rain in certain areas of the world as our climate warms.
Warm air holds more moisture, and previous research has found that global warming is already increasing the odds of extreme precipitation levels. However, climate models usually differ as to how that might play out at regional scales. While some models suggest that dry areas could become drier, new findings instead show that the rule does not hold over land.
In this latest study, the researchers defined extreme precipitation as the maximum rainfall or snowfall seen in a single day. They collected data on extreme precipitation from 11,000 weather stations using data recorded from 1951 to 2010. Then, the researchers found out which areas were wetter and drier than the global average and tracked changes in daily precipitation events.
So what did they find? Their results suggested that both annual precipitation and extreme precipitation increased by 1 to 2 percent per decade in dry regions, including western North America, Australia and parts of Asia. Wetter areas also showed similar increases in the size of extreme precipitation, though smaller increases in annual total.
"The paper is convincing and provides some useful insights," said Sonia Seneviratne, a climate scientist at the Swiss Federal Institute of Technology in Zurich. "What is particularly new in this article is the demonstration of such a signal for observed changes in dry regions."
The new results align with a 2015 study that found that global warming has boosted the number of record-breaking rainfall events. That approach provides more geographical detail about where major changes are happening.
The studies themselves bolster predictions from models that more extreme weather is on the way. They also confirm that even arid regions that may not usually receive heavy precipitation could be affected. While the study may not offer details about what kind of events to prepare for, it does put governments on alert.
"It is probably a good idea to invest infrastructure that helps in dealing with heavier precipitation, in particular if you are not yet used to those events," said Markus Donat, a climate scientist at the University of New South Wales in Sydney.