The Greenland ice sheet is melting unusually fast

GREENLAND’S misnomer is the result of a marketing campaign by Erik the Red who wished to attract Viking settlers to its icy landscape. Little did he know that the land had been covered in lush forests many millennia before he was born. Nor could he have fathomed that, a millennium after his death, the vast ice sheet would be in rapid retreat.

The ice atop Greenland holds enough water to raise global sea levels by more than seven metres, should it all melt and run off into the oceans. For this reason, climate scientists closely monitor its seasonal trends, and in particular how quickly it melts in the spring leading up to the late summer “ice minimum”, after which it starts to grow again.

The latest data show that the area of melting ice this year is unusually high. On June 12th 712,000 square kilometres of the ice-sheet (over 40% of the total) were melting. This is well outside the norm for the past 40 years (see chart).

Several factors are to blame. First, a natural cycle known as the North Atlantic Oscillation is encouraging ice-melt. Then there is long-term warming driven by rising greenhouse-gas emissions. Third, climate change has also weakened the jet stream, allowing a warm and humid weather system to settle over northeastern Greenland.

As a result, the seasonal ice melt began two weeks early. According to data published on the Polar Portal, a Danish climate-research website, Greenland is currently losing 3bn tonnes of ice every day, roughly three times the average for mid-June in 1981-2010.

The extent of the melting is not entirely unprecedented for this time of year. Researchers have seen similar events in 2002, 2007 and 2012. Each portended a record low at the end of the summer.

Although a switch in the weather could still turn things around, the early melt will result in darker snow and ice, which absorb more sunlight and hastens the melting process, says Thomas Mote of the US National Snow and Ice Data Centre.

“If this year is anything like 2012 [which set the current record for ice melt], then we will get in the region of 1mm of sea-level rise in one year just from Greenland,” says Jason Box, a professor at the Geological Survey of Denmark and Greenland. The oceans are rising by 3.3mm each year because of global warming.

Greenland may not be green, yet, but it is far less icy than in Erik’s time.

Editor's note (June 21st 2019): An updated version of this chart with more context can be found here