Greenland Glaciers Melt Faster Underwater

According to a new scientific investigation, it would appear that the glaciers in Greenland are melting a lot faster underwater, thnn they are at the surface. Experts in charge of the study, based at a NASA lab, and a number of universities in the US and Canada say that this difference could be attributed to the fact that the ocean is getting warmer. This produces a melting effect at the basis of the glaciers, which in turn destabilizes entire ice shelfs. If the Greenland cap were to melt, then sea levels could increase globally by a significant amount, the researchers add.

The work was conducted by scientists Eric Rignot and Isabella Velicogna, who both hold joint appointments at the NASA Jet Propulsion Laboratory (JPL), in Pasadena, California, and the University of California in Irvine (UCI). They collaborated closely with Canadian colleague Michele Koppes, who is based at the University of British Columbia (UBC), in Vancouver. During the summer of 2008, the investigators measured the warming rates recorded at the bottom end of four glaciers in Greenland. They used various types of oceanographic equipment for the job, and sampled water from various depths, from water inlets known as fjords.

They did that in order to assess the oceanic currents that are at work in the region, and also to measure the temperature, salinity and depth of the fjords. The group was able to determine that the melt rates of all four glaciers involved in the study were 100 times faster under the oceans than observed on the surface of the ice. This approach to studying the island, which has been largely overlooked by other researchers, has the ability to provide future computer model with a wealth of new data, that could more accurately simulate what the future global warming has in store for Greenland.

“Our study fills [existing gaps] by actually looking at these submarine melt rates, something that had never been done before in Greenland. The results indicate rather large values that have vast implications for the evolution of the glaciers if ocean waters within these fjords continue to warm,” Rignot says. Scientists know that if the ocean temperature increased to 3 degrees Celsius, or about 37 degrees Fahrenheit, then glacier melt rates can be boosted to as much as several meters per day. This amounts to several hundred meters over the course of a single summer.

“All major Greenland glaciers end up in the ocean, and tidewater glaciers control 90 percent of the ice discharged by Greenland into the sea. Submarine melting may therefore have a large indirect impact on the ice mass budget of the entire Greenland Ice Sheet. If we are to determine the future of the Greenland Ice Sheet more reliably in a changing climate, more complete and detailed studies of the interactions between ice and ocean at the ice sheet's margins are essential,” Rignot concludes.