The Greenland Ice Sheet may be sliding faster into the ocean than previously thought as a result of massive releases of meltwater from surface lakes, similar to snow sliding off of a roof on a sunny day, according to a new study by the University of Colorado.
The draining of lakes may also lead directly to sea level rise. This is the first evidence that researchers have to suggest that surface lakes have been draining more often as a result of the increase in meltwater rather than increase in size. The meltwater pools on the surface of the ice sheet during the summer months, and when pressure gets too high, the ice cracks and the water drains to the space between the ice sheet and the ground.
The research was done by using satellite images and feature recognition software, monitoring around 1000 lakes over a ten year period. As the climate has warmed, the massive glacial lakes have been draining more frequently, with drainages 3.5 times more likely to occur during the warmest years compared to the coldest years.
Around 1 million cubic meters of melt waterdrains to the ground in a day or two during a typical drainage.
Once there, it lubricates the surface of the ice sheet and the ground, and accelerates the slip into the ocean.
However the meltwater can also form drainage channels that flow directly into the ocean and stop the meltwater from building up enough to accelerate the slippage of the ice sheet.
Research associate William Colgan is quoted as saying, “Lake drainages are a wild card in terms of whether they enhance or decrease the ice sheet’s slide.”
Source: University of Colorado Boulder
Image Credits: Konrad Steffens/University of Colorado, Ted Pheffer/University of Colorado
