Greenland’s long, intense melt season is a worrying sign for sea levels
Greenland’s ice has been melting for a long time this summer, and the iconic intense melting event caused by heat waves. In mid-July, warm air intrusion from the Canadian Arctic caused a dramatic increase in the rate and extent of melt in northern Greenland, causing 18 billion tons of melt in just three days, enough to flood the entire state of West Virginia. a foot of water. Then, in early September, when the melt season was supposed to be drawing to a close, a late summer heatwave caused the first large melt surge on record. As the Arctic warms, extreme events become more common, with worrying knock-on effects on sea level rise.
The Arctic is warming faster than the rest of the planet, so melting in Greenland is increasing and happening at a faster rate due to more extreme heat events. The island currently has enough ice locked up that if it melted, sea levels would rise by 7.42 meters, and the ice is rapidly being lost due to the collapse of glaciers that terminate the ocean and faster ice flow into the sea. Seasonal melt also plays a role in Greenland’s contribution to sea level – every 360 billion tonnes of melt contributes 1mm to global sea level rise.
Between July 15 and 18, mild air from northern Canada met a high-pressure air system in Greenland, causing “heat ripples” in the north. The satellite captured a moderately broad melt surge, clearly showing a melt pool on the ice. The three-day heatwave melt was 35% higher than the average for that time of year, which is in line with the averages observed in 2012 and 2019 — the worst ice-melt years on record. In the days following the incident, widespread flooding occurred along the coast.
William Colganclimatologist Geological Survey of Denmark and Greenland, chat with GlacierHub. “The rate of melting in Greenland in July was unusual in the context of North Greenland,” he said. “The melt reached so much higher than usual that it hindered the operation of ski-equipped aircraft at the drilling site at an altitude of nearly 3,000 meters.” Colgan attributed the melt to “flow from lower latitudes into northern Greenland. an unusually large amount of warm, moist air.”
Map of Greenland’s melt level, showing peak melt levels in July and early September. Credit to the National Snow and Ice Data Center.
Despite the days-long extreme events, the number of melt days recorded this summer is close to average and similar to similar trends observed throughout the year.This National Snow and Ice Data CenterThe 2018 year that released Greenland melt data ranks 20th out of the 44-year record for total melt day area. But that doesn’t mean we shouldn’t worry about extreme events.
“These events really highlight that Greenland’s melting is moving into a warmer climate as extreme events become more frequent. If we maintain the same high carbon emissions climate trajectory, today’s extremes will become tomorrow’s averages,” Colgan said. Tell GlacierHub.
In the first few days of September, 35 percent of the ice cap is melting, compared with just 10 percent historically average for this time of year. This record-breaking melt event was caused by warm air moving north, on a day when the melt season was supposed to be nearing its end and temperatures were cooling. During the four-day event, the weather station recorded the highest temperature for the year, while at the Greenland summit, the temperature exceeded the melting point for the first time in recorded history. The warm weather was accompanied by heavy rainfall, which also contributed to the melting. The melt extended to Greenland’s northern and eastern coasts on September 4-5 as warm, moist air moved east.
A map showing the cumulative melt days in Greenland this year. Credit to the National Snow and Ice Data Center.
Meltwater runoff, the amount of surface water entering the ocean, peaked at just under 12 billion tons per day on September 3. This figure is more typical in July than in September, and is the highest daily value recorded for this melt season and the 10-day highest in runoff since 1950. “During the time of the year when melting is normally done, the ice sheet melt has soared to nearly 40 percent,” Colgan explained.
This is the second year in a row that end-of-season melt events have been observed. In mid-August last year, It’s raining on the mountain For the first time in Greenland, draw attention worldwide. At the time, the researchers said the rain-related melt event was the latest of the seasons they had seen.
Photo taken on September 2 by a team of researchers in southern Greenland, where they experienced rain and warm winds. Image credit: Mette Hansgaard/National Snow and Ice Data Center.
This unprecedented melting is happening as Greenland’s glaciers also face other new threats. Sarfartoq, a rare earth mine in southwest Greenland bought Canadian company Neo. Rare earth minerals are vital for many uses, including magnets for electric vehicles and wind turbines, two devices that can help reduce carbon emissions. The EU wants to reduce its reliance on China’s rare earth minerals through a Greenland mining project. The Sarfartoq site is close to glaciers and may therefore be affected by dust, other pollutants or runoff. Southwest Greenland has also experienced continued surface melt this season, which could complicate activities near the mines.
Regardless of the future of this mine, the climate impact continues. The intensity of Arctic warming is increasing and the summer melt season is getting longer, so events like those observed in July and September are expected to recur in the coming summer.
“There has been a general increase in ice loss from Greenland in recent decades, but there are differences between years. But, when you look at the 1990s and 2010s, for example, it’s clear that there has been an increase in ice loss,” Colgan said. Concluded in correspondence with GlacierHub.
Glacier disintegration, faster ice flow and increased meltwater runoff mean Greenland is losing ice at a worrying rate. If entire ice sheets melted into the ocean, coastal cities and communities around the world would disappear underwater. Although Greenland’s glaciers are located in remote locations, their increasing vulnerability affects people and ecosystems on every continent.
