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Climate Change: When It Rains It (Really) Pours

Study in ‘Science’ says warmer climates lead to more extreme rainstorms

Virginia Key, Fla. (August 8, 2008) — Climate models have long predicted that global warming will increase the intensity of extreme precipitation events. A new study conducted at the University of Miami and the University of Reading (U.K.) provides the first observational evidence to confirm the link between a warmer climate and more powerful rainstorms.

One of the most serious challenges humanity will face in response to global warming is adapting to changes in extreme weather events. Of utmost concern is that heavy rainstorms will become more common and more intense in a warmer climate due to the increased moisture available for condensation. More intense rain events increase the risk of flooding and can have substantial societal and economic impacts.

To understand how precipitation responds 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 Thursday, August 7, and published in an upcoming issue of Science, 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”

About the Rosenstiel School
Founded in the 1940's, the University of Miami's Rosenstiel School of Marine & Atmospheric Science has grown into one of the world's premier marine and atmospheric research institutions. Offering dynamic interdisciplinary academics, the Rosenstiel School is dedicated to helping communities to better understand the planet, participating in the establishment of environmental policies, and aiding in the improvement of society and quality of life.  For more information, please visit www.rsmas.miami.edu

About the Environmental Systems Science Centre (ESSC)
ESSC was established at the University of Reading in 1985 by the UK's Natural Environment Research Council (NERC) and undertakes interdisciplinary research into how life, land, oceans, atmosphere and ice sheets interact with each other. It forms an integral component of NERC's National Centre for Earth Observation and is linked with Reading's Meteorology department and Walker Institute for Climate System Research.  For more information, see www.nerc-essc.ac.uk

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