Last week, the Greenland ice sheet underwent a major melting event — its second in two weeks. This time around, the melting was quickened by a wholly unexpected and unwelcome visitor: rain.
Seven billion tons of rain fell on the country last week, and for the first time in recorded history, it rained at the Greenland Summit Camp, a research station near the normally frigid top of the ice sheet. Saturday was also only the third time this decade that temperatures ever rose above freezing at Greenland’s summit, according to the National Snow and Ice Data Centre.
The big melting event took place across two days last weekend. These large-scale melts can do serious damage to the ice sheet even if they only last a few days. The darker water can absorb the sun’s energy and cause the surrounding ice to melt faster, destabilizing the snow and firn below the surface. The blitz of water can screw up ice sheet dynamics in the longer term as well.
“During melt events, these processes can occur over parts of the ice sheet that do not typically experience melt, making the impact more widespread,” Lauren Andrews, a glaciologist with NASA’s Global Modelling and Assimilation Office, said in a statement to NASA’s Earth Observatory. “Positive feedbacks like these are starting to take their toll.”
The weekend of rain adds yet another wrinkle to the mix. In addition to melting ice, it also creates issues for when it inevitably refreezes. Ice made by the compression of snow and firn is generally pretty white and reflective. Ice by way of rain is relatively smooth and dark, though, which means it will absorb more of the sun’s rays and be more prone to melting.
On Saturday, the extent of ice affected by melting peaked at 872,000 square kilometres, roughly half of the massive ice sheet. About two-thirds of the ice sheet melted in late July, and this marks only the second year on record the ice sheet has seen more than one melt event of more than 800,000 square kilometres. What’s more, no melt event of that extent has ever been seen as late in the year as the one that just hit the ice sheet.
This summer is a warning sign of the horrors the climate crisis has in store. The Arctic is warming faster than anywhere else on Earth. Studies show that rain is becoming far more common, and that trend will continue as the climate crisis becomes more severe. A 2020 report found that some Arctic regions will begin seeing rain instead of snow in any month of the year, even during the traditionally frigid winter.
The Greenland ice sheet meltdown is only one impact. These shifts have also taken a massive toll on the region’s Indigenous populations and ecosystems, and they’re dangerous for those of us living far from the Arctic, too. Last week’s major Intergovernmental Panel on Climate Change report showed that melt from Greenland and Antarctica’s ice sheets is causing seas to rise faster than at any point in the last 3,000 years.
A 2019 study found that if the world keeps emitting greenhouse gases at an increasing rate, ice melt from Greenland alone could cause sea levels to rise between up to 0.3 metres by the end of the century, overwhelming coastal communities around the world. It would also eventually lead all of the ice sheet to disappear, albeit by the year 3000. That would raise sea levels 7 metres. The only way to ward off that fate is to rapidly, urgently kick fossil fuels to the curb and draw down greenhouse gas emissions. If we don’t, rain at the Greenland Summit Camp could become common — and could be the least of our problems.