(This story has been up to date with new knowledge from August 1.)
When one thinks of Greenland, photos of an icebound, harsh and forbidding panorama in all probability come to thoughts, not a panorama of ice pocked with soften ponds and streams remodeled into raging rivers. And nearly actually not one which options wildfires.
But the latter description is precisely what Greenland seemed like this week, in response to imagery shared on social media, scientists on the bottom and knowledge from satellites.
A unprecedented soften occasion that started earlier this week continued by August 1 on the Greenland ice sheet, and there are indicators that about 60 p.c of the expansive ice cowl noticed detectable floor melting, together with at increased elevations that solely not often see temperatures climb above freezing.
On Thursday, the ice sheet noticed its largest single-day quantity loss on document, with 12.5 billion tons of ice misplaced to the ocean from floor soften, in response to laptop mannequin estimates primarily based on satellite tv for pc and different knowledge. Information of each day mass loss date again to 1950.
“This mannequin, which makes use of climate knowledge and observations to construct a document of ice and snowfall, and web change in mass of the ice sheet, is remarkably correct,” says Ted Scambos, a senior researcher on the Nationwide Snow and Ice Knowledge Middle (NSIDC) in Colorado. “I might settle for the outcome as truth. 12.5 billion tons [lost] in at some point, and the very best single-day complete since 1950,” Scambos stated.
July 31 was the largest floor soften day since a minimum of 2012, with about 60 p.c of the ice sheet seeing a minimum of 1 millimeter of soften on the floor, and greater than 10 billion tons of ice misplaced to the ocean from floor soften, in response to knowledge from the Polar Portal, an internet site run by Danish polar analysis establishments, and the NSIDC.
In line with Ruth Mottram, a local weather researcher with the Danish Meteorological Institute, the ice sheet despatched 197 billion tons of water pouring into the Atlantic Ocean throughout July.
This is sufficient to increase sea ranges by 0.5 millimeter, or 0.02 inches, in a one-month time-frame, stated Martin Stendel, a researcher with the institute.
This might sound inconsequential, however each increment of sea-level rise offers a better launchpad for storms to extra simply flood coastal infrastructure, akin to New York’s subway system, components of which flooded throughout Hurricane Sandy in 2012. Consider a basketball recreation being performed on a courtroom whose flooring is steadily rising, making it simpler for even shorter gamers to dunk the ball.
Because of each floor melting and a scarcity of snow on the ice sheet this summer season, “that is the 12 months Greenland is contributing most to sea-level rise,” stated Marco Tedesco, a local weather scientist at Columbia College.
Due to an expansive space of excessive strain enveloping all of Greenland — the identical climate system that introduced excessive warmth to Europe final week — temperatures in Greenland have been working as much as 15 to 30 levels above common this week.
At Summit Station, which at 10,551 ft is situated on the highest level in Greenland and barely sees temperatures above freezing, the thermometer exceeded this mark for about 11 hours Tuesday, in response to Christopher Shuman, a glaciologist on the College of Maryland-Baltimore County and NASA Goddard Area Flight Middle.
The 2019 excessive soften occasion is being in comparison with a document excessive warmth and soften episode that occurred in Greenland in 2012. Whereas the extent of floor soften throughout that occasion might have exceeded this one to this point, Shuman discovered that Summit Station skilled heat that was better “in each magnitude and period” through the present occasion. The temperature solely remained above freezing about half as lengthy in 2012, and the height temperature reached 34.02 levels this 12 months, whereas it solely hit 33.73 in 2012. Through the 2012 excessive occasion, nonetheless, 97 p.c of the ice floor skilled melting.
“Like 2012, this soften occasion reached the very best elevations of the ice sheet, which is extremely uncommon,” says Thomas Mote, a professor of geography on the College of Georgia. “Each our satellite tv for pc observations and the ground-based observations from Summit indicated soften on Tuesday.”
“The occasion itself was uncommon that the nice and cozy air mass got here from the east, and seems to be part of the air mass that precipitated the record-breaking warmth wave in Europe. Most of our excessive soften days on the Greenland ice sheet are related to heat air lots transferring from the west and south. I can not recall an occasion the place we noticed such in depth soften related to an air mass coming from Northern Europe,” Mote stated.
The warmth, together with below-average precipitation in components of Greenland, has even sparked wildfires alongside the Greenland’s non-ice-covered western fringes. Satellite tv for pc photos and images taken from the bottom present fires burning in treeless areas, consuming mossy wetlands referred to as fen that may grow to be susceptible to fires after they dry out. These fires can burn into peatlands, releasing greenhouse gases buried way back by decomposition of natural matter.
Research have proven that ice soften durations just like the one seen in 2012 usually happen about each 250 years, so the truth that one other one is happening only some years later may very well be an indication of how local weather change is upping the chances of such occasions.
In line with DMI’s Mottram, the short-term, excessive soften occasion is an indication of local weather change’s rising affect on the Arctic.
“So sure it’s climate but it surely exhibits that despite inside variability the background sign of a warming local weather continues to be “profitable,” she stated through a Twitter message. She stated state-of-the-art local weather laptop fashions have been unable to simulate occasions like this, which hampers scientists’ skill to precisely predict Greenland ice soften and, subsequently, future sea-level rise.