Global Warming Articles:
Reading the Tree-Rings
Massive Pinyon Pine Die-off
Polar Melting
Hard Numbers on Global Warming
African Lake Demonstrates Effects of Global Warming
Global Climate Change Lecture Series
Fall 2006 Alumnus Global Warming update:
Forest Fires
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The University of Arizona Alumnus — Summer 2006 / Global Warming Polar Melting May Raise Sea Level Sooner Than Expected
The Earth’s warming temperatures are on track to melt the Greenland and Antarctic ice sheets sooner than previously thought and will ultimately lead to a global sea level rise of at least 20 feet, according to new research. If the current warming trends continue, by 2100 the Earth will likely be at least 4 degrees Fahrenheit warmer than at present, with the Arctic at least as warm as it was nearly 130,000 years ago. That’s when significant portions of the Greenland and Antarctic Ice Sheets melted, resulting in a sea level about 20 feet higher than today. These studies are the first to link Arctic and Antarctic melting during the Last Interglaciation, 129,000 to 116,000 years ago. “This is a real eye-opener set of results,” says study co-author Jonathan T. Overpeck of the UA. “The last time the Arctic was significantly warmer than present day, the Greenland Ice Sheet melted back the equivalent of 2 to 3 meters (about 6 to 10 feet) of sea level.” Contrary to what was previously believed, the research suggests the Antarctic ice sheet also melted substantially, contributing another 6 to 10 feet of sea level rise. The new findings were published in the March 24 issue of Science. Co-author Bette Otto-Bliesner of the National Center for Atmospheric Research in Boulder, Colo., notes, “Although the focus of our work is polar, the implications are global. These ice sheets melted before and sea levels rose. The warmth needed isn’t that much above present conditions.” The ice sheets are melting already. The new research suggests the melting could accelerate, thereby raising the sea level as fast, or faster, than 3 feet (about 1 meter) of sea level rise per century. Although ice sheet disintegration and the subsequent sea level rise lags behind rising temperatures, the process will become irreversible sometime in the second half of the 21st century, Overpeck says, “unless something is done to dramatically reduce human emissions of greenhouse gas pollution. “We need to start serious measures to reduce greenhouse gases within the next decade. If we don’t do something soon, we’re committed to 4-to-6 meters (13 to 20 feet) of sea level rise in the future.” As sea levels rise, coastal regions are more susceptible to the impacts of storm surge. The predicted rise would eventually inundate heavily populated coastal areas worldwide.  1. The pink and red areas in this image of areas along the Gulf of Mexico and Florida indicate places that would be submerged if the sea level rose about 20 feet (6 meters).  2. An image of the area around New Orleans, La., with the water shown in blue. The portions of the image colored pink and red represent areas that would be submerged if sea level rose about 3 feet (1 meter).  3. The red and pink areas in this image of the coasts of the states of Massachusetts and Rhode Island indicate the areas that would be submerged if the sea level rose about 20 feet (6 meters). Aerial images-charts (Courtesy of Jeremy Weiss and Jonathan Overpeck, The University of Arizona)
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