How climate change will make atmospheric rivers even worse – The Washington Post

by | Jan 12, 2023 | Climate Change

Comment on this storyCommentGift ArticleIn recent weeks, a slew of storms has slammed California, bringing torrential rains and deadly flooding. Storms are typical in the winter, including those associated with atmospheric rivers, or long and wide plumes of water vapor flowing from the tropics. But as Earth warms, climate scientists warn these atmospheric river events may be amplified, bringing even more destruction.In other words, the recent events could be just a modest preview of what’s to come in warmer years ahead.The impact of these storms is a paradox. Atmospheric rivers generally provide precipitation critical to a region’s water cycle. These massive rivers, which sometimes carry 15 times the water volume of the Mississippi River, deliver half of the western United States’ total precipitation in less than 15 total days.But too much rain in a short amount of time can have devastating effects on communities. Atmospheric rivers account for nearly 90 percent of California’s flood damage. Infrastructure has been destroyed and more than a dozen people have been killed by the storms of the past two weeks.Calif. storm triggers more floods, tornado warnings as death toll climbsTo help water managers and local authorities better prepare for future events, researchers are studying how a warmer world will influence the precipitation, intensity, location and societal effects of atmospheric rivers. In some aspects, climate change is already having detrimental effects on the systems.AdvertisementHere are four ways increased temperatures affect atmospheric rivers in the western United States.A series of atmospheric rivers struck California during the week of Jan. 9, causing floods, landslides, power outages and more across the state. (Video: John Farrell/The Washington Post)Heavier rainfallPerhaps one of the most well-understood aspects of climate change is its effect on rain. In a warmer atmosphere, evaporation rates increase and transform more liquid water molecules to a vapor state in the air. In fact, the atmosphere can hold about 7 percent more water for every 1-degree Celsius (1.8-degree Fahrenheit) increase. This moisture-laden air can drop heavier amounts of rainfall at one time, increasing the intensity of rain events.Earth’s atmosphere has warmed about 1.3 degrees Celsius (2.3 degrees Fahrenheit) since pre-industrial times, and researchers have already observed heavier rain in storms, hurricanes, daily precipitation — and now in atmospheric rivers.In a recent study, researchers found climate change increased the amount of rainfall from two atmospheric rivers in February 2017, which notably damaged Oroville Dam, California’s second-largest dam, and prompted the evacuation of 188,000 people. The atmospheric rivers produced about 11 and 15 percent more rain because of warming brought on by fossil fuel burning. If the same events were to take place in an even warmer world — as projected by the end of the 21st century — the researchers found rainfall quantities would have been 20 and 60 percent higher.Scientists will need to conduct a similar in-depth analysis of the current atmospheric activity to determine how human-caused climate change has played a part, but researchers say they wouldn’t be surprised to see heightened rainfall because of climate change. Other studies modeling future atmospheric rivers show rainfall will undoubtedly increase — up to 40 percent more — in a warming world.“We’re more than likely going to see more rain associated with atmospheric rivers and more precipitation in general,” said Allison Michaelis, an atmospheric researcher at Northern Illinois University and lead author of the recent study.AdvertisementShe added that some atmospheric rivers may be “more susceptible to the environmental changes associated with climate change” and show larger changes than others.More intense, costlier destructionAtmospheric rivers can be a bane or boon to l …

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