A giant ice sheet in Greenland has began melting at an alarming speed, a destabilisation that will cause global sea levels to rise for “decades to come”.
Called the Zachariæ Isstrøm glacier, it holds enough water to produce a half-metre rise in ocean levels globally.
Scientists looked at 40 years worth of satellite imagery of the glacier, establishing that “calving” off the front of the glacier is the main cause of concern.
“Ice floating out into the ocean and melting is greater than the ice lost from surface melting,” said John Paden, associate scientist for CReSIS who led the study.
“Ice loss is happening fast in glaciological terms, but slow in human terms – not all in one day or one year,” he said.
Not long to go
The rate at which the glacier is melting has tripled in recent years, with Paden noting that “within a few generations” the results could make a substantial, tangible difference.
“When you add up all the glaciers that are retreating, it will make a difference to a large number of people. Sea level has increased some over the last century, but only a small number of people have been affected compared to what is likely to come.”
This is radar depth-sounder data from before and after the breakup of the Zachariæ Isstrøm ice shelf. The green line reveals the ice bottom, and loss of ice between 1999-2014. The white line represents hydrostatic equilibrium estimates of the ice bottom – via University of Kansas
A huge concern is the ground on which Zachariæ Isstrøm rests, with the glacier essentially on a downslope, sending added water into the ocean.
A neighboring glacier with an equal amount of ice, named Nioghalvfjersfjorden, is also melting fast but receding gradually along an uphill bed, according to the researchers.
So until the ice recedes enough so that the land beneath it is more predominantly pointing upwards, we may be in trouble.
Ice in Greenland image, via Shutterstock