Atmospheric rivers could increase flood risk by 80 per cent

The global effect and impact of atmospheric rivers on rainfall, flooding and droughts has been estimated for the first time - revealing that in some regions the risks can be enhanced by up to 80 percent. The work, of which Oxford University is a key partner, also considers the number of people affected by these atmospheric phenomena across the globe. Atmospheric rivers get their name because they look like rivers of vapour in the sky. NASA, a collaborator in the research, defines them as relatively long, narrow, jets of air that can carry vapour as water, far and wide across some of the planet's oceans, on to the continents and as far as the polar regions. They are a form of extreme weather that can affect vast regions of the world, much like a tropical cyclone. The research estimates that, an average of almost 300 million people are exposed annually by flooding and droughts induced by atmospheric rivers. Although the percentage of the population affected by atmospheric river storms is comparatively small, they can still have significant impact. Atmospheric rivers were initially thought to have a significant effect on precipitation, rainfall and flooding in specific global regions.