The Greenland Ice Sheet, along with the Antarctic Ice Sheet, is one of the largest ice masses on Earth. It is the largest in the Northern Hemisphere, covering nearly 80% of Greenland’s land area and spanning over 1.7 million square kilometers. However, this ice sheet is rapidly thinning, alarming scientists.
At the end of the 2024 melt season, researchers from NASA and the European Space Agency (ESA) reported continued shrinkage. Since the summer of 2023, the Greenland Ice Sheet has lost about 80 gigatonnes of ice. The primary cause of this loss is rising temperatures.
“We are warming the planet, this is melting ice, and that is raising sea level,” said Richard Alley, a geologist and glacier expert at Pennsylvania State University. Alley added that while there are uncertainties over future sea level rise “if the big ice sheets change more rapidly than expected, they could drive faster or much faster rise than expected.”
Melting occurs both on the surface and along the edges of the ice sheet. The most significant changes are happening in the southern and western parts of Greenland, where large meltwater lakes form on top of the ice. These lakes can drain into the ice, weakening it further and speeding the melting process. This issue isn’t just a concern for Greenland, but for the entire world, as it contributes to rising sea levels globally. Higher seas can flood coastal areas, endangering both people and wildlife.
Researchers wondered where the melted ice went. After investigating, they were surprised to discover that melt ponds on the surface of the ice can disappear in just an hour or two. The water drains down to the bottom of the ice sheet through holes in the ice called moulins. Researchers believe that this meltwater reduces friction, allowing the ice to slide faster over the rocky surface. Researchers have also noted that the number of moulins is increasing.
As the glacier moves faster, it pushes more ice into the ocean. The meltwater that drains to the bottom of the ice sheet causes it to slip more easily toward the sea. Outlet glaciers (the paths through which ice flows to the ocean) are moving faster than ever before. For example, the Jakobshavn Glacier on the west side of Greenland has nearly doubled its speed in the past decade. Other glaciers have also accelerated by up to 50% during the summer melt season.
“What we think is happening over the few weeks of year when the most water flows down through the ice sheet, is that the sheet actually gets lifted up by the water as it starts to push between the bedrock or the sediments and the ice, reducing friction, acting as a lubricant. This is when we start to see the increase in velocity. It’s cyclical, and it all takes place over a peak in melting that goes on for a very short period of a couple of weeks,” said Professor Kondrad Steffen, Director of the WSL Institute for Forest, Snow and Landscape Research.
Scientists have come up with new plans for protecting these massive glaciers — and preventing the potentially devastating rise in sea levels that would occur if they vanished. One involves protecting vulnerable glaciers with underwater walls built by robots; the other involves pumping cold water through tunnels under the ice to thicken it and keep it from sliding into the ocean. Scientists are testing both ideas, and they hope that we can look after the Greenland ice for the future.