Andrew Dessler, a Texas A&M atmospheric sciences professor, and colleagues from the University of Colorado, the National Oceanic and Atmospheric Administration and the Science and Technology Corp. found increased surface temperatures, such as from adding carbon dioxide to the atmosphere, increases humidity in the stratosphere, the College Station, Texas, university said Monday in a release.
Stratospheric water vapor is a greenhouse gas and leads to additional warming called a climate feedback, the researchers said.
"We find that this stratospheric water vapor feedback is probably responsible for 5-10 percent of the total warming you get from adding carbon dioxide to the climate," Dessler said. "While it's not really surprising that this process is going on, we were surprised at how important the process is for our climate system."
Climate models already include this process, but unevenly, researchers said.
"It's clear to us that, if models want to make accurate predictions of climate change, they should get stratospheric water vapor right," said Sean Davis, of the University of Colorado-Boulder and study co-author. "A better understanding of the stratospheric water vapor feedback could help explain some of the spread among predictions of future climate change from different models" in the Intergovernmental Panel on Climate Change report last week.