July 4, 2011
Warmer Oceans Could Speed Melting Of Polar Ice
Sea levels could be rising faster than scientists originally believed, thanks to the warming subsurface waters that could cause more rapid melting of ice sheets in Greenland and Antarctica, researchers from the University of Arizona are claiming.
In a new study, University of Arizona Assistant Professor of Geosciences Jianjun Yin and colleagues analyzed 19 different climate models under which global warming would accelerate the melting of the world's largest ice sheets over the next two centuries.
They determined that the temperature of the subsurface ocean along the coast of Greenland could increase by more than three degrees Fahrenheit by the year 2100, compared to just 0.9 degrees Fahrenheit along the coast of Antarctica.
Those temperature differences could result in quicker melting of polar ice, the Associated Press (AP) reports, and "while melting floating ice won't raise sea level, ice flowing into the sea from glaciers often reaches the bottom, and grounded ice melted by warm water around it can produce added water to the sea."
The study--which was written by Yin and co-authors Jonathan T. Overpeck, co-director of UA's Institute of the Environment; assistant professor of geosciences Joellen L. Russell; Stephen M. Griffies and Ronald J. Stouffer of the National Oceanographic Atmospheric Administration's Geophysical Fluid Dynamics Laboratory in Princeton, N.J.; and Aixue Hu of the National Center for Atmospheric Research in Boulder, Colorado-- was scheduled to be published online in the journal Nature Geoscience on July 3.
"To my knowledge, this study is the first to quantify and compare future ocean warming around the Greenland and the Antarctic ice sheets using an ensemble of models," Yin said in a statement on Sunday. "Ocean warming is very important compared to atmospheric warming because water has a much larger heat capacity than air"¦ If you put an ice cube in a warm room, it will melt in several hours. But if you put an ice cube in a cup of warm water, it will disappear in just minutes."
"This mean that both Greenland and Antarctica are probably going to melt faster than the scientific community previously thought," added Overpeck. "This paper adds to the evidence that we could have sea level rise by the end of this century of around 1 meter and a good deal more in succeeding centuries."
According to a University of Arizona press release, the phenomenon could eventually result in the complete disintegration of Antarctic sheet ice, possibly as early as the 22nd century, and the next step for Yin and the research team will be to analyze climate models that can further elaborate on the regional impact of climate change on the ice sheets and subsurface ocean water.
Image 1: This view of the seaward edge of Antarctica's floating Ross Ice Shelf shows a region where the ice is cracking and may produce an iceberg. Credit: Michael Van Woert, NOAA NESDIS, ORA. National Oceanic and Atmospheric Administration/Department of Commerce
Image 2: This satellite image shows Greenland's Helheim glacier where it meets the sea. The glacier is on the left. Large and small icebergs pack the narrow fjord in the right part of the images. Bare ground appears brown or tan, while vegetation appears in shades of red. The Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) on NASA's Terra satellite took the image in June 2005. NASA images created by Jesse Allen, Earth Observatory, using data provided courtesy of NASA/GSFC/METI/ERSDAC/JAROS, and the U.S./Japan ASTER Science Team
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