Melting Greenland Ice Sheets May Threaten Northeast United States, Canada
Melting of the Greenland ice sheet this century may drive more water than previously thought toward the already threatened coastlines of New York, Boston, Halifax, and other cities in the northeastern United States and Canada, according to new research led by the National Center for Atmospheric Research (NCAR).
The study, which is being published Friday in Geophysical Research Letters, finds that if Greenland’s ice melts at moderate to high rates, ocean circulation by 2100 may shift and cause sea levels off the northeast coast of North America to rise by about 12 to 20 inches (about 30 to 50 centimeters) more than in other coastal areas. The research builds on recent reports that have found that sea level rise associated with global warming could adversely affect North America, and its findings suggest that the situation is more threatening than previously believed. …
NASA Earth Observatory: Melting on the Greenland Ice Cap, 2008
The northern fringes of Greenland’s ice sheet experienced extreme melting in 2008, according to NASA scientist Marco Tedesco and his colleagues. This image shows the number of days when melting occurred on the ice sheet compared to the average number of melt days between 1979 and 2007. Red outlines the northern rim and parts of the west coast of Greenland, indicating that the summer melting period in 2008 was longer than average in many places. Many locations in northern Greenland experienced a record number of melt days. Temperatures at nearby ground-based weather stations were correspondingly high. The average temperature between June and August 2008 was as much as 3 degrees Celsius above average, with new record temperatures at many ground-based weather stations.
University of Alaska Fairbanks (UAF): Study: Greenland ice sheet larger contributor to sea-level rise
The Greenland ice sheet is melting faster than expected according to a new study led by a University of Alaska Fairbanks researcher and published in the journal Hydrological Processes.
Study results indicate that the ice sheet may be responsible for nearly 25 percent of global sea rise in the past 13 years. The study also shows that seas now are rising by more than 3 millimeters a year–more than 50 percent faster than the average for the 20th century.
UAF researcher Sebastian H. Mernild and colleagues from the United States, United Kingdom and Denmark discovered that from 1995 to 2007, overall precipitation on the ice sheet decreased while surface ablation–the combination of evaporation, melting and calving of the ice sheet–increased. According to Mernild’s new data, since 1995 the ice sheet lost an average of 265 cubic kilometers per year, which has contributed to about 0.7 millimeters per year in global sea level rise. These figures do not include thermal expansion–the expansion of the ice volume in response to heat–so the contribution could be up to twice that. …
The research article is published in the Wiley Interscience journal “Hydrological Processes”: Greenland Ice Sheet surface mass-balance modelling and freshwater flux for 2007, and in a 1995-2007 perspective
Global Glacier Changes: facts and figures
There is mounting evidence that climate change is triggering a shrinking and thinning of many glaciers world-wide which may eventually put at risk water supplies for hundreds of millions — if not billions — of people. Data gaps exist in some vulnerable parts of the globe undermining the ability to provide precise early warning for countries and populations at risk. If the trend continues and governments fail to agree on deep and decisive emission reductions at the crucial UN climate convention meeting in Copenhagen in 2009, it is possible that glaciers may completely disappear from many mountain ranges in the 21st century.
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ScienceDaily: Ice Sheets Can Retreat ‘In A Geologic Instant,’ Study Of Prehistoric Glacier Shows
Modern glaciers, such as those making up the Greenland and Antarctic ice sheets, are capable of undergoing periods of rapid shrinkage or retreat, according to new findings by paleoclimatologists at the University at Buffalo.
The paper, published on June 21 in Nature Geoscience, describes fieldwork demonstrating that a prehistoric glacier in the Canadian Arctic rapidly retreated in just a few hundred years.
The proof of such rapid retreat of ice sheets provides one of the few explicit confirmations that this phenomenon occurs.
Should the same conditions recur today, which the UB scientists say is very possible, they would result in sharply rising global sea levels, which would threaten coastal populations. …
Nature GeoScience: Rapid early Holocene retreat of a Laurentide outlet glacier through an Arctic fjord doi:10.1038/ngeo556
Marine-terminating outlet glaciers control the stability of ice sheets. Exposure ages and radiocarbon dates show that an Arctic outlet glacier of the Laurentide ice sheet rapidly retreated about 9,500 years ago, and imply strong feedbacks between bathymetry and ice movement. …