Collapse of a Greenland Glacier Would Raise Sea Levels by 18 Inches

The glacier has become unmoored, dropping 5 billion tons of ice into the ocean every year.

A research team, led by the Polar Space Task Group consisting of scientists from NASA and the University of Kansas, found that a glacier in northeast Greenland has unmoored from a stabilizing sill and is collapsing into the Atlantic Ocean.

The glacier, named Zachariae Isstrom, entered a phase of ‘accelerated retreat’ in 2012. This term is used to describe a substantially increase in the rate of glacial melting, but in the case of Zachariae Isstrom, the pace has actually tripled. The driving forces behind this rapid melt are both warmer atmospheric temperatures and ocean temperatures, and ice mass is being lost at a rate of five billion tonnes per year.

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The research group used a radar sounder, gravimeter and laser profilers, along with radar and images from space to monitor and record the changes of shape, size and position of the glacier.

Lead author Jeremie Mouginot, an associate project scientist in the Department of Earth Science at the University of California, Irvine stated, “The shape and dynamics of Zachariae Isstrom have changed dramatically over the last few years. The glacier is now breaking up and calving high volumes of icebergs into the ocean, which will result in rising sea levels for decades to come”.

The current rate of sea-level rise is between 0.8 and 3.3 millimeters per year, but the complete collapse of Zachariae Isstrom would result in a sea level rise of 18 inches. That is an alarming number. The U.S. National Assessment estimated the cumulative cost of an 18-inch sea level rise by 2100 to be between $20 and $200 billion. A three-foot rise in sea-level would double those figures.

Zachariae Isstrom is not the only glacier on Greenland in a state of retreat. Nioghalvfjerdsfjorden is also melting at a rapid rate, but it is slower than Zachariae because it is protected by an inland hill. These two glaciers make up 12 percent of Greenland’s ice sheet and the complete collapse of just these two glaciers would result in a rise of sea level by more than 39 inches.

“Not long ago, we wondered about the effect on sea levels if Earth’s major glaciers were to start retreating” said Eric Rignot, Chancellor’s Professor of Earth System Science at University of California, Irvine. “We no longer need to wonder.”

The effects of climate change are felt strongest in the Arctic regions, so it is unsurprising that more and more glaciers are entering a state of accelerated retreat. Research into the glaciers on Greenland and Antarctica is continued through funding from NASA’s Cryospheric Sciences Program.