‘Sky rivers’ will pose increasing threat to East Asia as climate crisis worsens

Atmospheric rivers – narrow bands transporting large volumes of moisture in the air – are becoming more common in mountainous regions such as the Japanese Alps, causing record-breaking precipitation events.

The warning comes following a study conducted at the University of Tsukuba, Japan. Using historical trends and a future scenario in which global-mean surface air temperature increases by four degrees, the research team modelled how current patterns will develop in coming years. 

Focusing on what some have termed ‘sky rivers’, which have caused a number of extreme weather events in East Asia over the last decade, results showed that as global temperatures climb so too will the prevalence of these bands of water. In turn, the cost of their impact on economies and societies will also increase. 

This is due to how atmospheric rivers behave. Carrying vast amounts of water in the air, problems arise when these channels meet an obstacle, for example a mountain range. At this point, the phenomenon turns into rainfall, with the potential to drop huge levels of precipitation over a relatively small area, raising the risk of flash flooding, landslides, and other disasters. 

‘To investigate the behaviour of atmospheric rivers and extreme precipitation over East Asia under projected climate warming, we used high-resolution global atmospheric circulation model simulations as well as regional climate model downscaling simulations,’ said Professor Yoichi Kamae, first author of the study.

‘We compared simulations based on historical meteorological data from 1951 to 2010 with future simulations based on the year 2090 under a climate scenario with four degrees Celsius of warming of the global-mean surface air temperature,’ he explained. 

Currently, atmospheric rivers have been most commonplace in Japan, where the greatest extreme rainfall events have taken place on the slopes of the Alps; the Korean Peninsula, Taiwan, and the north-east of China have also been notable impacted. Future simulations predict higher levels of water vapour being transported, more super-precipitation, and record breaking downpours. 

In related news, last week Germany’s Potsdam Institute for Climate Impact Research and Mercator Research Institute on Global Commons and Climate Change released a joint study that shows a direct link between the number of localised rainy days and regional economic performance. 

Photo credit: Leo Mendes