More on GIS melt:
https://www.wired.com/story/icy-waterfa ... greenland/
June and July are shaping up to be the most intense Arctic wildfire periods on record with blazes raging everywhere from Siberia and Alaska to even Greenland.
Although fires are a natural part of the boreal forest life cycle, the magnitude and number of the fires this season are unheard of with The World Meteorological Organization (WMO), a specialized agency of the United Nations, calling the wildfire spasm “unprecedented” in a news release this month.
So far, fires have been most severe in Alaska and Siberia, with some fires covering up to 100,000 football fields, says the WMO.
In all, the Copernicus Atmosphere Monitoring Service (CAMS), implemented by the European Centre for Medium-Range Weather Forecasts on behalf of the European Comission, has tracked more than 100 wildfires within the Arctic Circle this season, with numerous others raging across the North.
The area of the Greenland ice sheet that is showing indications of melt has been growing daily, and hit a record 56.5% for this year on Wednesday, said Ruth Mottram, a climate scientist with the Danish Meteorological Institute. She says that’s expected to expand and peak on Thursday before cooler temperatures slow the pace of the melt.
More than 10 billion tons (11 billion U.S. tons) of ice was lost to the oceans by surface melt on Wednesday alone, creating a net mass ice loss of some 197 billion tons (217 billion U.S. tons) from Greenland in July, she said.
Mottram said since June 1 — roughly the start of the ice-loss season — the Greenland ice sheet has lost 240 gigatons (240 billion metric tons) this year. That compares with 290 gigatons lost overall in the 2012 melt season, which usually goes through the end of August.
A lot of what melts can later refreeze onto the ice sheet, but because of the conditions ahead of this summer’s heat wave, the amount of ice lost for good this year might be the same as in 2012 or more, according to scientists. They noted a long build up to this summer’s ice melt — including higher overall temperatures for months — and a very dry winter with little snow in many places, which would normally offer some protection to glacier ice.
Greenland is losing ice seven times faster than it was in the 1990s. The assessment comes from an international team of polar scientists who've reviewed all the satellite observations over a 26-year period.
They say Greenland's contribution to sea-level rise is currently tracking what had been regarded as a pessimistic projection of the future.
It means [at least] an additional 7cm of ocean rise could now be expected by the end of the century from Greenland alone.
"Storms, if they happen against a baseline of higher seas - they will break flood defences," said Prof Andy Shepherd, of Leeds University. "The simple formula is that around the planet, six million people are brought into a flooding situation for every centimetre of sea-level rise. So, when you hear about a centimetre rise, it does have impacts," he told BBC News.
Greenland is reacting to the Arctic's rapid warming. This is a part of the globe that has seen a 0.75C temperature rise in just the past decade.
In recent decades, the Greenland Ice Sheet has been a major contributor to global sea-level rise1,2, and it is expected to be so in the future3. Although increases in glacier flow4–6 and surface melting7–9 have been driven by oceanic10–12 and atmospheric13,14 warming, the degree and trajectory of today’s imbalance remain uncertain. Here we compare and combine 26 individual satellite measurements of changes in the ice sheet’s volume, flow and gravitational potential to produce a reconciled estimate of its mass balance. Although the ice sheet was close to a state of balance in the 1990s, annual losses have risen since then, peaking at 335 ± 62 billion tonnes per year in 2011. In all, Greenland lost 3,800 ± 339 billion tonnes of ice between 1992 and 2018, causing the mean sea level to rise by 10.6 ± 0.9 millimetres. Using three regional climate models, we show that reduced surface mass balance has driven 1,971 ± 555 billion tonnes (52%) of the ice loss owing to increased meltwater runoff. The remaining 1,827 ± 538 billion tonnes (48%) of ice loss was due to increased glacier discharge, which rose from 41 ± 37 billion tonnes per year in the 1990s to 87 ± 25 billion tonnes per year since then. Between 2013 and 2017, the total rate of ice loss slowed to 217 ± 32 billion tonnes per year, on average, as atmospheric circulation favoured cooler conditions15 and as ocean temperatures fell at the terminus of Jakobshavn Isbræ16. Cumulative ice losses from Greenland as a whole have been close to the IPCC’s predicted rates for their high-end climate warming scenario17, which forecast an additional 50 to 120 millimetres of global sea-level rise by 2100 when compared to their central estimate.
The current depends on the saltiness of the North Atlantic to create the sinking motion of water, that is, it’s the “pump” driving the current. Saltier water is heavier than fresh water.
As the Greenland ice sheet melts, large volumes of fresh water enter the North Atlantic and freshen the very salty sea water, slowing the “pump,” Jorgen Peder Steffensen of the University of Copenhagen explains in the video, produced for Yale Climate Connections by independent videographer Peter Sinclair of Midland, Michigan.
“That would make it terribly cold in Denmark, where I come from,” Steffensen says. “In principle, there’s no reason why Earth could not get warmer but still northern Europe and North America could get cold. Still, that area is not large compared to the global area.”
Melting ice from Greenland largely explains the freshening North Atlantic, Box agrees.
“We are 50 to a hundred years ahead of schedule with the slowdown of this ocean circulation pattern, relative to the models,” according to Mann.
“The more observations we get, the more sophisticated our models become, the more we’re learning that things can happen faster, and with a greater magnitude, than we predicted just years ago.”
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