Analyzing the Effect of Climate Change on Atmospheric Rivers in North America

Atmospheric rivers (ARs) are enormous streams of water vapor typically found in the midlatitude regions of both hemispheres of Earth; extending for several thousand kilometers in length and several hundred kilometers in width, and transporting up to 15 times more water than the Mississippi River, ARs are extremely potent sources of precipitation, hence they are responsible for severe flooding along the west coasts of the United States, UK, and elsewhere. To understand how climate change might affect the frequency of ARs in the future, we analyzed the results of both historical and projected climate simulations, identified atmospheric river events within them along the northwest coast of the United States, and compared the distributions of AR events by month from the two simulations. Ultimately, we found that under the RCP8.5 scenario—the “worst case scenario” for climate change—ARs along the northwest coast of the United States are projected to occur almost three times as frequently by the end of the 21st century as they do currently, suggesting that humans should continue to mitigate climate change lest the world’s coastlines become dangerously exposed to these severe, hurricane-like precipitation events.Ope