A recent study has indicated that the Jakobshavn Glacier in Greenland is experiencing a rapid melt that threatens to raise sea levels by up to one centimeter.
The glacier, which is thought to have yielded the iceberg that ended the Titanic’s fated voyage, has begun to melt at an alarming rate, about four times faster than it was reducing in the 1990s. This puts it at the top of the glacier-melting charts, making it the fastest flowing river of ice in the world.
The recent research project, published in the Cryosphere journal, examined images from the German TerraSAR-X satellites to monitor the speed of the glacier.
"As the glacier moves we can track changes between images to produce maps of the ice flow velocity," said Dr. Ian Joughin, lead author of the study carried out at University of Washington’s Polar Science Center in Seattle.
The findings indicated that, during the warmer months of 2012, the glacier was moving at speeds of up 17km per year – more than 46m per day, though this rate was seen to decrease during the winter months.
"We are now seeing summer speeds more than four times what they were in the 1990s on a glacier which at that time was believed to be one of the fastest, if not the fastest, glacier in Greenland," explained Dr. Joughin.
The rapid melt is giving scientists cause for concern, because if it were to disappear completely, sea levels could rise by up to 6 meters. Jakobshavn, which is located in the south-west of Greenland, is believed to be unstable state and is likely to retreat further inland in the future.
"We know that from 2000 to 2010 this glacier alone increased sea level by about 1mm. With the additional speed it likely will contribute a bit more than this over the next decade," said Joughin.
Despite this worrying possibility, Prof Jonathan Bamber, a glaciologist from the University of Bristol, told BBC News that it can be normal for some surging glaciers to experience a fast rate of flow for short periods. During warmer periods, glaciers have been reducing and releasing icebergs, or "calving," and withdrawing further inland, so though they appear to be transporting their icy cargo seaward, they are actually drawing further and further back.
The study found that during the past two years the distance retreated was typically around a kilometer more than in previous years. If the trend continues, the calving front of the glacier could have retreated up to 50km upstream to the head of the fjord.
So, what is causing this rapid increase in the glacier’s thawing patterns? Rising sea temperatures have been suggested, but the findings of another recent study, published in the journal Science, indicated that the causes were broader and linked to global climate variability. The "La Nina" weather phenomenon, an irregular pattern of water cooling occurring near the equatorial Pacific, is thought to be a contributing factor. La Nina is linked to widespread changes in weather patterns, similar to that of El Niño, but the effects are less extensive and damaging.
“These new results show that how much melt the Antarctic ice sheet experiences can be highly dependent on climatic conditions occurring elsewhere on the planet,” explained study co-author Eric Steig, a University of Washington professor of earth and space sciences.
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