Half a decade before he took this trip to the farthest reaches of the north, Andreas Muenchow had his doubts about whether warming temperatures were causing one of the world’s great platforms of ice to melt and fall apart.
He even stood before Congress in 2010 and balked on whether climate change might have caused a mammoth chunk of ice, four times the size of Manhattan, to break off from this floating, 300-square-mile shelf. The University of Delaware oceanographer said he wasn’t sure. He needed more evidence.
But then the Petermann Ice Shelf lost another two Manhattans of ice in 2012, and Muenchow decided to see for himself, launching a project to study the ice shelf intensively.
He was back again in late August, no longer a skeptic. It was hard not to be a believer here at 81 degrees north latitude, where Greenland and Canada very nearly touch. The surface of the bumpy and misshapen ice was covered with pools and puddles, in some cases frozen over but with piercing blue water beneath. Streams carved through the vast shelf, swelling into larger ponds or even small lakes.
NASA has been using satellites to measure changing sea levels around the globe. SPOILER ALERT: Sea levels are rising. They’ve gone up more than two inches in the last two decades.
A lot of the uncertainty involved in predicting future sea level rise comes from the status of the Greenland Ice Sheet. NASA’s Oceans Melting Greenland program (or OMG - that’s really what they’re calling it) is using a host of monitoring techniques to try and predict just how fast all that ice will melt.
Seasonal melt is normal in Greenland: Parts of the ice sheet melt each spring and then freeze again when the weather gets cold. But this year, when climate scientists at the Danish Meteorological Institute began to measure the seasonal melt, the data was unlike anything they had ever seen before. Here’s how much higher the temperature is compared to last year.
Scientists say [that the Greenland ice sheet] has already lost more than 9 trillions tons of ice in the past century — and the melting rate only continues to increase as temperatures keep warming. NASA estimates that the Greenland ice sheet is losing about 287 billion tons of ice every year, partly due to surface melting and partly due to the calving of large chunks of ice.
The new study, published Monday in the journal Nature Climate Change, focuses on a part of the ice sheet known as “firn” — a porous layer of built-up snow that slowly freezes into ice over time. It’s considered an important part of the ice sheet because of its ability to trap and store excess water before it’s able to run off the surface of the glacier, an essential service that helps mitigate the sea-level rise that would otherwise be caused by the runoff water.
“As this layer is porous and the pores are connected, theoretically all the pore space in this firn layer can be used to store meltwater percolating into the firn whenever melt occurs at the surface,” said the new paper’s lead author, Horst Machguth of the Geological Survey of Denmark and Greenland, in an email to The Washington Post. Over time, the percolating meltwater trickles down through the firn and refreezes.
Until recently, many scientists have assumed that most of Greenland’s firn space is still available for trapping meltwater. But the new research shows that this is likely no longer the case. Through on-the-ground observations, the scientists have shown that the recent formation of dense ice layers near the ice sheet’s surface are making it more difficult for liquid water to percolate into the firn — meaning it’s forced to run off instead.
These two videos, one from UCLA and one from NASA, might help explain this:
Droplets of water fall from a melting ice block, which was harvested in Greenland and installed in Place du Pantheon in Paris, France, December 3rd 2015. Twelve ice blocks have been arranged in a clock formation for an artwork called ‘Ice Watch Paris’. They will gradually melt away throughout the World Climate Change Conference 2015 (COP21), which continues at Le Bourget near the French capital. Credit: Reuters/Benoit Tessier