'Massive melting event' sinks billions of tons of Greenland ice amid heat wave
Image from one of the Copernicus Sentinel-2 satellites captures the severe water discharge from melting glaciers into the Arctic Ocean as a result of unusually high temperatures in Greenland.
Scientists are raising alarms that ice has vanished from the Greenland ice sheet in a dramatic melting event in recent weeks. So much so that the liquid released could cover the entire state of Florida with 2 inches of water.
Home to the world's second-largest ice sheet, only behind Antarctica, Greenland's 656,000 square-miles of ice play a crucial role in containing the majority of the world's freshwater supply. Over 99% of the world's freshwater ice supply is stored in the ice sheets between Greenland and the Antarctic.
But in the final few days of July, an extreme heat wave sent temperatures skyrocketing in the northern portion of Greenland, hitting a high of 74 degrees Fahrenheit on July 29 at the Nerleit Inaat Airport. According to the Polar Portal, a site run by Danish research institutions that monitor the Greenland ice sheet, that heat wave triggered what was dubbed a "massive melting event."
Mark Puleo
Fri, August 6, 2021, 6:06 PM·5 min read
Image from one of the Copernicus Sentinel-2 satellites captures the severe water discharge from melting glaciers into the Arctic Ocean as a result of unusually high temperatures in Greenland.
Scientists are raising alarms that ice has vanished from the Greenland ice sheet in a dramatic melting event in recent weeks. So much so that the liquid released could cover the entire state of Florida with 2 inches of water.
Home to the world's second-largest ice sheet, only behind Antarctica, Greenland's 656,000 square-miles of ice play a crucial role in containing the majority of the world's freshwater supply. Over 99% of the world's freshwater ice supply is stored in the ice sheets between Greenland and the Antarctic.
But in the final few days of July, an extreme heat wave sent temperatures skyrocketing in the northern portion of Greenland, hitting a high of 74 degrees Fahrenheit on July 29 at the Nerleit Inaat Airport. According to the Polar Portal, a site run by Danish research institutions that monitor the Greenland ice sheet, that heat wave triggered what was dubbed a "massive melting event."
As the heat wave pushed temperatures nearly 70 degrees Fahrenheit above seasonal norms, over 8 billion tons of ice sank into the ocean on four consecutive days of last week. From July 28 to Aug. 4, nearly 60 billion tons of ice have been lost, according to data from Polar Portal.
"It's quite an interesting melt event though," Dr. Ruth Mottram told AccuWeather in an email. "I think it is worth pointing out that prior to this recent heat wave, the mass budget of the ice sheet had been above average due to the large amount of snow that fell in early summer."
FILE - In this Aug. 16, 2019 file photo, icebergs float away as the sun rises near Kulusuk, Greenland. According to a study released on Thursday, Aug. 20, 2020, Greenland lost a record amount of ice during an extra warm 2019, with the melt massive enough to cover California in more than four feet (1.25 meters) of water. (AP Photo/Felipe Dana, File)
Mottram, a climate scientist at Danish Meteorological Institute, added that a particularly rainy summer has also shifted the melting dynamics even before the record-breaking heat arrived. In some areas, that rain has proven helpful when it freezes and adds to the ice layer.
In warmer locations, however, the opposite can occur.
"The rain that falls on the ice sheet can refreeze if there is a deep surface snow pack so it actually helps the ice sheet gain ice," she said. "But in other regions, where the snow is thin, rain can accelerate melt and can have an effect on ice sheet dynamics."
Once that ice melts, some of it flows directly into the ocean and adds to the ongoing problem of sea-level rise, and ice that refreezes sets the stage for more melting in the future.
This is the second summer of severe melting in recent years, as 2019 also brought unfathomable losses to the ice sheet. In a single day that summer, 11 billion tons of ice were lost.
Areas of Greenland are seen from the air as U.S. Secretary of State Antony Blinken takes an aerial tour of ice caps and fjords near Kangerlussuaq, Greenland, Thursday, May 20, 2021. Blinken traveled to Greenland for a brief visit to reinforce U.S. commitment to the island. (Saul Loeb/Pool Photo via AP)
According to Mottram, the quantity of this year's ice loss may be eye-popping, but the real unique twist with this year's melting is the vast area in which the melting is occurring.
"The melt event was unusual not just in total amounts but because it was very widespread with large amounts of surface melt at quite high altitudes over the ice sheet," she said. "Ice cores show that these widespread melt events were really rare prior to the 21st century, but since then, we have had several melt seasons."
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She pointed specifically to the years of 2002, 2010, 2012, 2019 and now 2021 for those notable seasons, before adding that "we are really seeing a new normal" in regards to the ice melt at higher elevations.
While Montross did add that this high-elevation melt is not contributing to sea-level rise in most cases, due to the fact that it refreezes in underlying snow, experts such as Brad Lipovsky told The Guardian that the sea-level rise is hard to stop once it gets started.
رد: مناقشة الأحوال الجوية السائدة والمتوقعة خلال أشهر 7+8+9 سنة 2021
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