March 18, 2013
Greenland’s Peripheral Glaciers Also Contribute Significantly To Sea-Level Rise
Alan McStravick for redOrbit.com - Your Universe Online
The oft-clichÃ© idea behind the naming of Iceland and Greenland claims their names were derived in an attempt to fool would be sailing marauders, attracting them to the desolate but more hospitably named Greenland, leaving the citizens of Iceland to live upon their slightly more lush island without threat of invasion.
In fact, Erik the Red, it is believed, gave the moniker to attract settlers to the ice covered island just to the northeast of North America.
Greenland is the world´s largest island. Nearly 80 percent is covered by an ice sheet that has existed for the last 400,000-800,000 years. Associated with, but independent from the mainland ice sheet, scientists are exploring how Greenland´s glaciers will play a role in the impending sea-level rise. Their study, entitled “Mass loss of Greenland´s glaciers and ice caps 2003 — 2008 revealed from ICESat laser altimetry data,” has been published in the journal Geophysical Research Letters.
Dr. Tobias Bolch of the University of Zurich and lead author of the study stated, “The melting of ice on Greenland is known to be one of the major sources for global sea-level rise. Beside the large ice sheet, there are thousands of peripheral glaciers which are not connected to the ice sheet or can be separated from it due to the existence of ice divides.” Bolch continues, saying, “The area of those glaciers is about 50 times higher than the ice cover of the European Alps. Consequently, it is important to investigate not only the ice sheet but also these local glaciers.”
The team employed the use of lasers to measure the height of the ice from space. They were able to complete an inventory of Greenland´s glaciers and ice caps which helped in determining changes in the mass of the glaciers, separate from the main ice sheet.
The most interesting find for the team had to do with the glacier's relationship to the contribution to sea-level rise. They found the glaciers made up some 10 percent of the entire world´s glaciers and ice caps. This finding, they state, was considerably higher than they had originally expected.
From their research, the team was able to ascertain that glaciers that presented no connection or, at best, a weak connection to the main ice sheet contributed to around 30 gigatons of water per year to sea level between the years of 2003 and 2008. A gigaton is equivalent to 1 cubic kilometer of water.
Furthermore, when the scientists included glaciers which had some link to the main ice sheet, though they still presented distinct flow movement, the contribution to increased sea level was measured at around 50 gigatons per year. To understand this amount, the team compared it to one of Europe´s largest lakes, Lake Geneva. 50 gigatons is equal to just more than half the volume of this lake.
Additionally, the researchers claim their study provides even more detail of the make-up and stability of Greenland´s glaciers. They claim their results show mass loss is markedly higher in the warmer south east and lowest in the colder north.
Their data also showed a loss of ice that is an estimated 2.5 times higher for the separate glaciers than for the ice sheet. It was this data that accounted for the 15-20 percent figure noted by the team.
According to Dr. Bolch, “The other 80-85 percent comes from the ice sheet. The new figure for the local glaciers is higher than expected. It matters because the ice loss with respect to the area is significantly higher than of the ice sheet. This means that the local glaciers react faster with respect to climate change. This information will help to improve the predictions of the future contribution of Greenland´s ice to sea-level rise.”
The program known as Ice2sea is a European scientific collaborative comprised of experts from 24 leading institutions across Europe and the globe. Data and study from the Ice2sea program will prove integral in the composition of the fifth Intergovernmental Panel on Climate Change (IPCC) report, due this year. The fourth report to the IPCC, in 2007, had highlighted ice-sheets as the most significant remaining uncertainty in projections of sea-level rise, stating the crucial ice-sheet effects was “too limited to assess their likelihood or provide a best estimate of an upper bound for sea-level rise.”
The results of this study and their contribution to the upcoming report will, no doubt, present important ramifications for a substantial percentage of the world´s population. It has been estimated that a full 23 percent of the world´s population resides in what are known as “coastal zones.” The effects of sea-level rise will, at best, be disruptive to these communities. At its worst, sea-level rise will present catastrophic consequences to the peoples and lands of these coastal zones.