Some climate models have predicted that global warming will increase the intensity of extreme precipitation events but a new study conducted at the University of Miami and the University of Reading (U.K.) says their observational evidence confirms the link between a warmer climate and more powerful rainstorms.
It's no more scientifically accurate to imply this year's floods were caused by or made worse by global warming than it was for Al Gore to imply global warming caused Hurricane Katrina but there is no question more intense rain events increase the risk of flooding and can have substantial societal and economic impacts.
To predict how precipitation might respond to a warmer climate, researchers in this study used naturally-driven changes associated with El Niño as a laboratory for testing their hypotheses. Based on 20 years of satellite observations, they found a distinct link between tropical rainfall extremes and temperature, with heavy rain events increasing during warm periods and decreasing during cold periods.
"A warmer atmosphere contains larger amounts of moisture which boosts the intensity of heavy downpours," said Dr. Brian J. Soden, associate professor at the University of Miami Rosenstiel School of Marine & Atmospheric Science.
The report, “Atmospheric Warming and the Amplification of Precipitation Extremes,” previewed in Science Express this week, found that both observations and models indicated an increase in heavy rainstorms in response to a warmer climate. However, the observed amplification of rainfall extremes was found to be substantially larger in the observations than what is predicted by current models.
“Comparing observations with results from computer models improves understanding of how rainfall responds to a warming world” said Dr. Richard P. Allan, NERC advance fellow at the University of Reading’s Environmental Systems Science Centre. “Differences can relate to deficiencies in the measurements, or the models used to predict future climatic change”