Environment Writer
A GLACIER in Greenland that holds enough water to raise sea levels by 45cm has come “unmoored” and is crumbling into the Atlantic Ocean, according to research published in Science.
Scientists from the University of California said the glacier was losing mass at a rate of five billion tons a year, having entered an accelerated retreat in 2012.
Lead author Jeremie Mouginot, who with colleagues had studied changes to the major Zachariæ Isstrøm glacier, said glaciers in the north of Greenland were changing rapidly. “The shape and dynamics of Zachariæ Isstrøm has 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.”
The research team used data from aerial surveys and satellites from international space agencies. This data recorded changes in the shape, size and position of glacial ice over long periods.
What they established was that the Zachariæ Isstrøm glacier was being “hit from above and below” because of global climate change.
Senior author Eric Rignot said: “The top of the glacier is melting away as a result of decades of steadily increasing air temperatures, while its underside is compromised by currents carrying warmer ocean water. The glacier is now breaking away into bits and pieces and retreating into deeper ground.”
Asked to estimate the time it would take for the glacier to melt entirely, Mouginot said this had not formed part of the study.
“It would be a completely different study to do that. Here we show that a new sector of Greenland – the north-east – is now losing mass from enhanced ice discharge. Our study also shows that the retreat was triggered by warmer air and ocean temperatures.
“Although rather speculative, we think that the glacier will retreat another 20 to 30km inland in the coming decades, but for the entire glacier basin, it will take centuries or more.”