Rain increases the melt rate because of its temperature, its darker color than the original paler ice, its falling on places that ordinarily don’t melt at all, and its weight (water being denser than snow or ice). Rain in Greenland is bad news.If Greenland loses its ice, ocean levels will go up quite a bit. Read “New York 2140” by Kim Stanley Robinson for a portrait of the future.
It Rained at the Summit of Greenland’s Ice Sheet for the First Time Ever Recorded
The rain triggered widespread ice melt—a warning sign for what the climate crisis may have in store.
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 Center.
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 Modeling 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.
Before and after satellite images showing the impact of rain on the Greenland ice sheet. The cloud-free image was acquired on Aug. 12, 2021 while the rainy one was acquired on Aug. 15, 2021.Gif: Gizmodo (NASA Earth Observatory)
On Saturday, the extent of ice affected by melting peaked at 337,000 square miles (872,000 square kilometers), 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 309,000 square miles (800,000 square kilometers). 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.
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 a foot (.3 meters) 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 23 feet (7 meters). 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.