WASHINGTON — In the past few years, the term “atmospheric rivers” has become increasingly common in everyday conversations, especially in areas impacted by severe weather events. This shift aligns with an observed rise in these meteorological phenomena.
Recent research published in the Journal of Climate highlights a significant growth in the frequency, intensity, and reach of atmospheric rivers. Known for their role in delivering heavy rainfall and strong winds, particularly to regions like California, these weather systems have expanded their coverage area by 6 to 9% since 1980. They have become 2 to 6% more frequent and carry a higher moisture content than in the past, suggesting a link to global warming trends.
Atmospheric rivers are expansive, narrow corridors of water vapor traveling from the ocean, resulting in intense precipitation when they hit land. As global temperatures continue to rise due to the combustion of fossil fuels, the atmosphere holds more moisture, leading to these more substantial atmospheric rivers. The study presents this increase in atmospheric moisture as evidence that a wetter future, previously predicted, is already unfolding.
Lead author Lexi Henny, formerly of NASA and now an atmospheric scientist at the University of North Carolina, points out that while their study did not specifically investigate the causes, the findings are consistent with predicted changes due to climate warming. However, she cautions that the current transformations may only be a fraction of what can be anticipated in the future.
Although beneficial in bringing rainfall to arid areas, atmospheric rivers pose a serious risk when they are particularly potent and prolonged. For instance, a series of atmospheric rivers over a year ago led to numerous mudslides and fatalities in California. Historical records from the 1860s document that Sacramento had to temporarily relocate its capital due to severe flooding caused by these systems.
Atmospheric rivers are not just a West Coast phenomenon; they occur throughout the United States and globally, though they may not always be identified as such. For example, New England experienced an atmospheric river in 2023 that resulted in substantial rainfall and strong winds, while a 2020 event in Alaska deposited an astonishing 99 inches of snow.
Experts like Christine Shields from the National Center for Atmospheric Research, who was not involved in the study, commend the paper for its valuable insights and data. These findings are crucial to improving our understanding and forecasting of intense precipitation and snowfall linked to atmospheric rivers in times to come.
This coverage is supported by various private foundations, with all content being independently managed. More information on standards and funding for climate and environmental reporting is available through AP.
