A recent study finds that atmospheric moisture in arid and semi-arid regions is not rising as predicted with global warming, posing new challenges for climate science and raising concerns about heightened risks of wildfires and extreme weather.
The laws of thermodynamics dictate that a warmer atmosphere can hold more water vapor, but new research has found that atmospheric moisture has not increased as expected over arid and semi-arid regions of the world as the climate has warmed.
The findings are particularly puzzling because climate models have been predicting that the atmosphere will become more moist, even over dry regions. If the atmosphere is drier than anticipated, arid and semi-arid regions may be even more vulnerable to future wildfires and extreme heat than projected.
The authors of the new study, led by the U.S. National Science Foundation National Center for Atmospheric Research (NSF NCAR), are uncertain what’s causing the discrepancy.
“The impacts could be potentially severe,” said NSF NCAR scientist Isla Simpson, lead author of the study. “This is a global problem, and it’s something that is completely unexpected given our climate model results.”
Simpson and her co-authors say follow-up research is needed to determine why water vapor is not increasing. The reasons could have to do with moisture not moving from Earth’s surface into the atmosphere as projected or circulating around the atmosphere in unanticipated ways. It’s also possible that an entirely different mechanism could be responsible.
Adding to the mystery, the new study showed that while water vapor is increasing over humid regions of the world, it is not rising as much as expected during the most arid months of the year.
The study appears this week in the Proceedings of the National Academy of Sciences. The research was funded by the National Science Foundation, DOI: 10.1073/pnas.2302480120
This material is based upon work supported by the National Center for Atmospheric Research, a major facility sponsored by the National Science Foundation and managed by the University Corporation for Atmospheric Research. Any opinions, findings and conclusions or recommendations expressed in this material do not necessarily reflect the views of the National Science Foundation.