Glaciers, including the Greenland ice sheet, hold about three-quarters of the world's fresh water, according to the U.S. Geological Survey. They are a vital part of the water supply for many communities, and if they melt, the sea level will rise catastrophically.
But that may be what we're facing, especially if a worrying trend continues: It's raining more often on Greenland's ice cap, Grist reported.
What happened?
The effects of rain in the Arctic have been poorly understood, as this is a relatively rare phenomenon that has only begun to be studied recently.
However, in August 2021, rain fell on the summit of the ice cap in Greenland, allowing University of Montana glaciologist Joel Harper to collect data. A huge amount of snow melted and the snow line retreated 2,000 feet, Grist reported.
By comparing the event to previously unexplained data from 2008, Harper was able to determine that the same thing had happened that year, but much later in the autumn. That time, it had rained for four days, while the temperature rose by over 50 degrees.
Why does it matter if it rains in the Arctic?
In the past, the Arctic got very little precipitation, and most of that was snow, Grist reported. However, as the world is getting warmer, rain is becoming more common.
Rain on permafrost behaves differently from snow. Instead of settling on top, it can penetrate into the existing layers of snow and ice — by as much as 20 feet, during the fall 2008 rains — and change the underlying structure of the ice, Grist said. That changes the flow of future meltwater.
Not only that but, as Harper explained to Grist, each rain event changes the structure in ways that make it more vulnerable to future changes. "It suggests that only a minor increase in frequency and intensity of similar rain-on-snow events in the future will have an outsized impact," he said.
This is just one more threat to ice caps and glaciers that are already in danger of melting, threatening both the communities that rely on meltwater and the coast.
Mark Serreze, director of the National Snow and Ice Data Center at the University of Colorado, predicted that as more of the Arctic melts, it will accelerate changes in the weather and speed the process. "We are trying to keep up with what is going on," he told Grist, "but we keep getting surprised."
What can be done about melting glaciers?
In the long term, the only solution is to reduce air pollution so that we can lower the Earth's overall temperature. Individuals can help by switching from gas to electric cars and appliances, supporting businesses with eco-friendly practices, and voting for greener policies.
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