XPost: talk.environment, sci.environment, soc.culture.nordic

https://www.accuweather.com/en/weather-news/massive-melting-event-sinks-billions-of-tons-of-ice-amid-heat-wave/993907

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."

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.

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."

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.

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.

“The alarming thing to me is the political response, or lack of it,"
said Lipovsky, a glaciologist at the University of Washington.
"Sea-level rise is like a slow-moving train, but once it gets rolling
you can’t stop it. It’s not great news.”

Such extreme melting could trigger future melting concerns, glacier
expert Marco Tedesco told the Guardian, creating a feedback loop of
sorts. As the white snow melts, the ice sheet loses its protective
layer against the sun, thus exposing darker ground underneath which
absorbs more heat and triggers further melting.

It may be many decades or even centuries before the entire Greenland
ice sheet could entirely melt, but its impact on the rising sea level
has already had a startling effect, scientists say.

“It’s a very high level of melting and it will probably change the
face of Greenland, because it will be a very strong driver for an acceleration of future melting, and therefore sea level rise,”
Tedesco told the Guardian, before adding that these extreme melting
events have happened in the past but not at this frequency. “It’s
amazing to see how vulnerable these huge, giant areas of ice are. I’m astonished at how powerful the forces acting on them are.”

--
Job Bautista

An XUL fanatic, and an add-ons developer. I also do some simple
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I like Cyndaquil. He's obviously the best Pokemon starter. Every Johto
Pokemon is cool too.

http://rw.rs/~job/

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