Understanding the Rapid Acceleration of Greenland’s Glaciers
16.09.2009 - Water & Oceans, Ice & Snow, Other, Arctic
Glaciers across Greenland have been flowing to the ocean at an increasing rate over the last decade. This has meant more icebergs calving off the end of the glaciers, contributing to global sea level rise. With snowfall on top of the ice sheet not enough to replenish it, the Greenland Ice Sheet is estimated to be losing 200 million cubic metres of ice a year - enough to fill 80,000 Olympic-sized swimming pools.
The true contribution of the melting ice sheets covering Greenland and Antarctica to global sea level rise were overlooked in the IPCC's Fourth Assessment Report, which predicted global sea level to rise by 20 to 60 cm this century. Now scientists have revised their projections for future sea-level rise, believing that it could be double.
For some time scientists have hypothesized that meltwater underneath the glaciers was acting as a lubricant, increasing flow rate towards the ocean. However now many scientists believe that pulses of warmer water from southern latitudes entering Greenland's fjords and coming up to the glacier seems to be the cause.
Both David Holland, director of the Center for Atmosphere Ocean Science (CAOS) at New York University and a separate team of researchers from the Woods Hole Oceanographic Institution in Massachusetts led by Fiamma Stranneo found that this water was reaching the edge of Greenland's largest glacier, the Jakobshavn Glacier (aka Sermeq Kujalleq or Jakobshavn Isbrae). In July, the world's oceans were the warmest in the 130 years of record keeping.
One bright patch is that researchers have noticed that some but not all glaciers across Greenland have seen similar slowdowns in the past few years. However the current flow rate of Greenland's glaciers still means a net loss of ice form the ice sheet, and as the planet warms, sudden spurts of speed may become more common, draining inland ice and causing the ice to collapse.
