According to a University of Washington study published in Nature Climate Change , there is a 90% likelihood that temperatures will rise between 2C and 4.9C by 2100. This would put the world in the mid-range warming scenario mapped out by the UN’s Intergovernmental Panel on Climate Change (IPCC) according to The Guardian. They report that it negates the most optimistic outcome as well as the worst case, which would see temperatures climb nearly 6C beyond the pre-industrial era. This suggests that we should be very concerned about our future and it reveals that not only do we need to go to zero emissions immediately, but that we must also figure out how to suck CO2 out of the atmosphere. In a nutshell we have only a 5% chance of keeping the upper limit of temperature rise below the 2C limit by 2100 set by the Paris Climate Agreement.
The Arctic is warming twice as fast as the rest of the world and in Greenland, which is the largest chunk of ice on the planet, warming alone can’t explain the severe erosion of it’s ice cap. There is now a undeniable trend of unseasonably warm summers and winters. Microbes and algae, which grow on the wet surface from early snow melting, 24 hour sun and lot’s of liquid water on the ice sheet, produce colors that boost absorption of solar energy. Soot and dust from our fossil fuel emissions and climate change enhanced grass and forest fires that blow from lower latitudes and darken the ice play a role, as do changes in weather patterns that increasingly steer warm, moist air over the vulnerable ice.
Andrea Thompson of Climate Central reports on 2017 summer snowfall.
While there were some bouts of melting earlier in the summer, the weather has since shifted. In recent weeks, summer snows have topped up that already unusually high snow load. Right now, the ice sheet’s surface has about 1.2 times the amount of mass than normal; at the same point in 2012, it had 1.2 times less than normal, Box said.
Also inhibiting summer melt this year is the unusually southerly position of the jet stream, caused by a climate pattern called the North Atlantic Oscillation. “That’s keeping Greenland relatively cold,” Box said.
While snowy weather may seem at odds with a warming world, Greenland could actually see more of it as temperatures rise. A warmer atmosphere can hold more moisture, which means that when storms pass through, they drop more precipitation. When temperatures are below freezing, as they are for much of Greenland through most of the year, that means more snowfall. (Rain has been falling at the expense of snow in the lower third of the island as temperatures rise above freezing, though.)
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For the first decade or so of this century, there were more clear skies over Greenland, and so increased melt. But atmospheric patterns seem to have flipped around in recent years, and Tedesco and others are still working on figuring out how changing atmospheric patterns might be influencing snowfall and melt on the ice sheet to better predict how it will progress with future warming.
This year’s excess snowfall doesn’t mean that melt isn’t still happening, though. Melt has already picked back up since the last summer snow earlier this month, Box said. In fact, he expects that that snow will now be a layer of slush he’ll have to trudge through when he arrives on the ice sheet this week to check on a network of weather stations.
The snow could, however, balance out the year’s melt, Box said, with the ice sheet ending up with no net loss of ice for the year — the first year that will have happened in two decades.
Thompson notes that “one year without a net loss also doesn’t buck the long-term trend of Greenland losing ice, both from surface melt and from ocean waters eating away at glaciers that flow out to sea”.
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Meltwater fills bus-sized fractures near the edge of the Greenland Ice Sheet, while dust and algae darken adjacent ice.Chris Mooney of the Washington Post writes that wildfires can cause Greenland to melt from thousands of miles away.
For the first time, scientists have tracked soot from Canadian wildfires all the way to the Greenland ice sheet where the dark, sunlight-absorbing particles landed on the ice and had the potential to significantly enhance its melting — pointing to a possible new driver of sea level rise.
It's the first end-to-end documentation of a process that, it's feared, could hasten Greenland's melting in the future — and since the ice sheet could contribute more than 20 feet of eventual sea level rise, any such process is one that scientists weigh carefully.
"That's the first time we've been able to connect that whole logic chain from, here's a fire and here's where it ended up on the ice sheet," said Chris Polashenski, one of the study's authors and a researcher with the U.S. Army Corps of Engineers' Cold Regions Research and Engineering Laboratory.
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Soot — which emerges from combustion and is largely composed of a substance called black carbon — influences a property of snow called albedo, or reflectivity. Whiter ice reflects more solar rays back to space. Pools of water and dark particles reduce the reflectivity of the ice sheet, allowing it to absorb more heat. Water is less reflective than pure snow – and in some cases the growth of biological life in ponds atop the ice sheets also causes darkening, which speeds the melting process.The study, which only examined a single event, was not able to document a trend toward an increased deposition of soot atop Greenland due to a larger number of wildfires. But it certainly hints at the possibility that such a trend could occur.
x xYouTube VideoResearchers have been fanning out over the Greenland ice sheet recently to study microorganisms and how they help to determine the pace of Arctic melting. Cryoconite holes are water-filled depressions on the surface of glaciers. These holes contain microbial communities and contribute to migration of microorganisms which contribute to glacial wasting and biological colonization of ice-free areas.
The journal Nature News reports that researchers are fanning out across Greenland’s ice sheet to study this worrying phenomenon.
For decades, most studies on Greenland microbiology focused on cryoconite holes, small pits on the surface of the ice sheet that are filled with dark organic matter and ice-adapted algae. But enormous blooms of photosynthetic algae also cover the snow-strewn ice sheet every summer1. Some, such as Chlamydomonas nivalis, spread first as greenish blooms as they begin to photosynthesize, and then turn a reddish colour as they produce carotenoid pigments to protect themselves from the sun’s ultraviolet rays.
“They’re extremely lazy algae — they sleep for nine months and then wake up and have a party,” says team member Liane Benning, a biogeochemist at the University of Leeds, UK, and the GeoForschungsZentrum research centre in Potsdam, Germany.
The algae creates vast, colourful fields of what is popularly known as 'watermelon snow'. Last month in Nature Communications, Benning and her team reported sampling watermelon snow at glaciers across the Arctic2. They found 6 types of algae living at 40 red-snow sites in Norway, Sweden, Greenland and Iceland. By comparing the optical properties of red snow to clean snow, they estimated that algal blooms could reduce reflectivity by 13% over the melting season. “Wherever we look, the impact is quite dramatic,” Benning says.
After the snow cover melts for the season, other species of alga take over. These ice-adapted algae are typically brownish-grey, less visibly dramatic than the red and green blooms but just as important for darkening the ice sheet. Only in the past few years have scientists begun to realize that some of the dark particles on the ice sheet are in fact these ice algae and not soot, Benning says.
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