December 2019
Vol 5, Issue 12

About The Cover

Cover image expansion

ONLINE COVER Satellite and aircraft observations have previously confirmed that atmospheric rivers (ARs)—extratropical storms that produce extreme precipitation—cause significant floods in the U.S., especially the western region due to the air mass lifting over mountainous regions. Like "rivers in the sky," ARs transport on average more than double the flow of the Amazon River in water vapor outside of the tropics. Despite its catastrophic impact, the cost of damages by ARs has not yet been quantified. Using 40 years of data from the National Flood Insurance Program (NFIP), Corringham et al. have found that ARs are the primary drivers of flood damages in the western U.S. In a warmer climate, the researchers warn, ARs will become wetter, longer and wider (with some indication this is already happening in relation to Pacific Ocean warming)—which is expected to exacerbate AR-driven financial cost. They suggest the hefty economic impact of ARs, and the possibility of it worsening, signals an urgent need to improve tracking and prediction of AR frequency and intensity, as well as a need to bolster flood control strategies, including alternative approaches like green infrastructure. [CREDIT: IRFAN KHAN /LOS ANGELES TIMES VIA GETTY IMAGES]