Climate change could cause larger and more frequent extreme weather events, a new study by University of Otago has found.
The Waiho Bridge on State Highway 6 washed away in April 2019 after torrential rain battered the West Coast for two days.
Photo: Wayne Costello / DOC
The research aimed to find the causes and impact of atmospheric rivers - thin concentrated corridors of airborne moisture which could produce severe rainfall.
Lead author of the study Hamish Prince said as the climate warmed these may become more common and intense. In very basic terms, one of the results of a warmer climate is a wetter atmosphere. With more moisture in the atmosphere the frequency and magnitude of atmospheric rivers making landfall in New Zealand are expected to increase.
“Interestingly, atmospheric river storms are found to produce more than two times more daily rainfall than non-AR storms at most [rainfall weather] stations, and significantly more than three times for the west side of mountainous areas and northern New Zealand,” researchers Assad Shamseldin, Evan Weller and Jingxiang Shu, of the University of Auckland, found.
Nasa/Supplied
This Nasa image shows an atmospheric river hitting California in 2014. They play an essential role in regional water resources and are responsible for many extreme rainfall events on the western side of mountainous areas and northern New Zealand. “Depending on the season in these areas, 40 per cent to 86 per cent of the rainfall totals and 50 per cent to 98 per cent of extreme rainfall events are shown to be associated with atmospheric rivers,” the researchers found.