Water Vapor & Climate Change: New Study Confirms Global Warming Predictions

October 07, 2005 — By University of Miami Rosenstiel School of Marine & Atmospheric Science

Virginia Key, FL — A new study published in this week’s issue of Science confirms evidence of global warming using satellite measurements of water vapor — a well-known greenhouse gas — in the troposphere.

Using satellite measurements of water vapor from 1982 to 2004, Dr. Brian Soden from the University of Miami Rosenstiel School of Marine & Atmospheric Science and colleagues were able to confirm the climate model simulations that have long indicated that moisture is increasing in the upper troposphere and this water vapor build up is exacerbating global warming. Their findings are published in the paper, “The Radiative Signature of Upper Tropospheric Moistening.”

“The importance of water vapor in regulating climate is undisputed. It is the dominant greenhouse gas, trapping more of the Earth’s heat than any other gaseous constituent,” wrote Soden and his co-authors Darren L. Jackson from the University of Colorado Cooperative Institute for Research in Environmental Sciences, V. Ramaswamy and M.D. Schwarzrzkopf from NOAA’s Geophysical Fluid Dynamics Laboratory, and Xianglei Huang at the Princeton University Atmospheric and Oceanic Sciences Program.

Water vapor is not only the dominant greenhouse gas, but its concentration also depends strongly upon temperature. As the climate warms from the burning of fossil fuels, the concentrations of water vapor are expected to increase. This moistening of the atmosphere, in turn, absorbs more heat and further raises the temperature. In this way, water vapor greatly amplifies the global warming projected to occur over the next century.

In this study, the researchers took satellite observations from the High-Resolution Infrared Radiometer Sounder (HIRS) to document an increase in atmospheric water vapor in the upper troposphere – a region of the atmosphere, which extends from roughly 5-12 km above the surface where the greenhouse effect from water vapor is particularly potent. The HIRS has been providing global measurements at consistent time intervals and in the same vapor absorption band within the troposphere from 1979 to present. The scientists determined that the concentration of water vapor there has increased over the past 20 years in a manner consistent with climate model simulations and could double by the end of the century due to projected increases in other greenhouse gases.

“Up until now, our ability to detect such changes had been limited by inadequate observational data,” Soden said. “What’s most significant about our research is that we have identified a distinct characteristic of moistening in the satellite record. We can now see how the climate’s behavior is consistent with current models, validating their accuracy and their projections of future global warming.”

About the Rosenstiel School
Rosenstiel School is part of the University of Miami and, since its founding in the 1940s, has grown into one of the world’s premier marine and atmospheric research institutions.

Media Contacts
Ivy Kupec
(305) 421-4704

Annie Reisewitz
305) 284-1601
www.rsmas.miami.edu