The National Center for Atmospheric Research in Boulder, Colo., in a study funded by NASA, analyzed how well 16 leading sophisticated climate models reproduce observed relative humidity in Earth's tropics and subtropics.
The models that most accurately captured these complex moisture processes and associated clouds, which have a major influence on global climate, were also the ones that showed the greatest amounts of warming as humanity puts more and more greenhouse gases into the atmosphere, NASA said.
"There is a striking relationship between how well climate models simulate relative humidity in key areas and how much warming they show in response to increasing carbon dioxide," NCAR scientist John Fasullo said. "Given how fundamental these processes are to clouds and the overall global climate, our findings indicate that warming is likely to be on the high side of current projections."
The findings, published in the journal Science, could improve the longstanding quest to narrow the range of global warming expected in coming decades and beyond, the researchers said.