Melting Ice Sheet in Greenland Becomes the Largest Contributor to Global Sea Level Rise

Experts had observed extremely high melting rates at the bottom of Greenland ice sheets, making it the current "single largest contributor" to global sea level rise, according to a new study.

The vast body of ice covering nearly 80% of Greenland's surface is melting in a very alarming rate. New study warns that this "unprecedented rate" of melting "from the bottom up" is by far the largest heat source beneath the world's second largest ice sheet, next to Antarctic.

As huge quantities of meltwater fall from the surface to the base, energy is converted into heat in a way similar to how hydroelectric power is generated by large dams, contributing largely to sea level rise around the globe, Mail Online explained.

In addition, meltwater has 'lubricating effect' to the movement of glaciers and the amount of ice discharged into the ocean, which is still a major challenge for researchers to measure, especially in Greenland where glaciers move the fastest.

Understanding the dynamic behavior of the Greenland Ice Sheet

Measuring a depth of more than half a mile of ice poses a challenging condition for experts in understanding the dynamic behavior of the ice sheets and predicting future changes of the planet's most important and largest ice mass, as described in VOX.

A team of international researchers led by the University of Cambridge digs into the subglacial drainage systems regulating ice sheet flow and the quantity of ice discharged into the ocean. A new study published in Proceedings of the National Academy of Sciences (PNAS) shows how these systems are currently poorly characterized due to lack of direct observations.

To be able to predict sea level changes regardless of uncertainty, the team attributes both observations and conversion of potential energy of surface water to heat in meltwater lakes. With this they unravel how and why they drain so quickly and how this affected the overall behavior of the ice sheet in a world where temperatures continue to rise.

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Climate change and sea level rise

"When studying basal melting of ice sheets and glaciers, we look at sources of heat like friction, geothermal energy, latent heat released where water freezes and heat losses into the ice above," said Professor Poul Christoffersen from Cambridge's Scott Polar Research Institute.

They found a lot of gravitational energy stored in the draining meltwater at the surface and as it falls, and it "has to go somewhere."

Using a radio-echo sounding technique developed at the British Antarctic Survey and used previously on floating ice sheets in Antarctica, they found that the basal melt rates were as high as those measured on the surface, regardless of the fact that the surface receives heat from the sun while the base does not.

The team calculated an estimate of 82 million cubic meters of meltwater transferred to the bed of Store Glacier every day during the summer of 2014,and the power produced by the falling water during peak melt periods was comparable to the power produced by the Three Gorges Dam in China, the world's largest hydroelectric power station.

"Given what we are witnessing at the high latitudes in terms of climate change, this form of hydropower could easily double or triple, and we're still not even including these numbers when we estimate the ice sheet's contribution to sea level rise," said Christoffersen.

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