Science

Climate change causing Greenland ice sheets to melt faster

Climate change causing Greenland ice sheets to melt faster

For the study published Monday in the Proceedings of the National Academy of Sciences, the team found the rate of ice loss had accelerated to almost four times what it was in 2003 by 2012, much of that coming not from glaciers calving into the sea but from large rivers of meltwater from the ice sheet itself.

Greenland, the world's biggest island, appears to have hit a tipping point around 2002-2003 when the ice loss rapidly accelerated, said lead author Michael Bevis, a geoscientist at Ohio State University.

The melting, which Professor Bevis and his colleagues believe is caused largely by global warming, is causing growing rivers of water to stream into the ocean from Greenland during the milder summer months.

Mount Rainier's glaciers have been melting surprisingly slowly, even adding ice in certain places, while Greenland's massive ice sheets melt at four times the rate of just 15 years ago.

Bevis: A lot of recent focus has been on increasing rates of glacial discharge, often driven by ocean warming.

And there is no turning back, Bevis said.

The total amount of ice in the Antarctic, if it all melted, would be enough to raise sea levels 57 metres.

Researchers say the ice rate loss across Greenland has increased four-fold since 2003, which they say will lead to a greater sea level rise.

Gravity Recovery and Climate Experiment (Grace) involves twin satellites that measure ice loss across Greenland. Southwest Greenland is losing ice most of all.




The warming of Greenland, the accelerating loss of sea ice near Greenland, and the accelerating loss of ice mass in Greenland will certainly prove very damaging to its existing ecosystems.

Bevis' team used data from GRACE and from Global Positioning System stations scattered around Greenland's coast to identify changes in ice mass. "But if you take ice mass off of Greenland and put it directly into the sea at a faster rate than anyone is modeling, that would imply that sea-level projections are maybe a little conservative", said Kaitlin Keegan, a Dartmouth research associate.

Global atmospheric warming enhances summertime melting, especially in the south west. "This is horrifying really", said Michael Bevis. And furthermore, this effect could not be made, at least partially, even in the case of a stop of global warming will be reversed.

He said: "These oscillations have been happening forever".

The culprit appears to be climate change, which combines with a natural air-current phenomenon - the North Atlantic Oscillation - to pummel Greenland with warm air. When these enormous storm systems find warm pockets of ocean water, they intensify rapidly, making them hard to be predicted with accuracy. Because of climate change, the base temperature is already close to the critical temperature at which coral bleaches, so an El Niño pushes the temperature over the critical threshold value.

They say this suggests that the surface ice is simply melting as global temperatures rise.

Data from these satellites showed that between 2002 and 2016, Greenland lost about 280 gigatonnes of ice per year, equivalent to 0.03 inches of sea level rise each year.

But Prof Bevis said the new findings show that scientists need to be watching the island's snowpack and ice fields more closely.