Active NASA Photo of Arctic Sea Ice
Arctic Ocean Could Be Ice-Free Before Midcentury
From an Article by Tim Radford, Climate Network News, November 5, 2016
The average American is responsible for the melting of almost 50 square meters of ice per year.
LONDON — Two scientists have worked out what it would take to melt all the ice in the Arctic Ocean.
If their sums are right, then by the time human beings have burned enough fossil fuels to add 1,000 billion tons of carbon dioxide to the atmosphere, the Arctic Ocean will be free of ice in September—the annual minimum—and the world’s shipping will have a new, safe, fast route across the Arctic Circle.
Quite when this moment will happen depends entirely on the rate that humans add greenhouse gases to the atmosphere. But the two researchers calculate that for every metric ton of carbon dioxide emitted, the Arctic will lose 3.3 square metres of sea ice.
Melt rate: That means the average American, with the world’s highest use of fossil fuels per head, is now melting almost 50 square metres a year.
Right now, humanity in total is releasing 35 billion tons of CO2 into the atmosphere each year, so the 1,000-billion-ton mark will be achieved before mid-century, and the north polar ocean ice will drop for the first time below 1 million square kilometres, leaving the Arctic almost entirely open sea.
Climate scientists predicted years ago that—at present rates of melting—the Arctic could be ice-free in September by mid-century. What Dirk Notz of the Max Planck Institute for Meteorology in Hamburg in Germany and Julienne Stroeve of the National Snow and Ice Data Center (NSIDC) in Boulder, Colorado, in the US, report in the US journal Science is that they have established a direct correlation between emissions and ice loss.
They looked at the average area of sea ice every September for the last 30 years—since satellite instruments began to deliver accurate data—and matched that against the cumulative carbon emissions for the last three decades.
The two call the relationship “robust”: there might be all sorts of reasons why over a long historical period Arctic sea ice would vary from year to year, but as greenhouse gas levels rise, CO2 becomes the dominant force that makes the ice retreat.
This year the ice began melting with great rapidity, and according to the NSIDC the area of frozen sea dwindled to an average of 4.72 million square kilometres, the fifth lowest in the satellite record. It is now freezing again, very fast.
Arctic waters: But the US Office of Naval Research reports that it has already begun to explore the open waters. Researchers this summer began measuring the strength and intensity of waves and swells moving through the increasingly weakened sea ice. They also used acoustic sensors to test the conditions for sonar operations and antisubmarine warfare.
That is because the retreat of the ice opens up new commercial shipping lanes, makes possible greater oil and gas exploration and new fisheries—and new challenges for the US Navy’s surface fleet. The goal is to understand the changing conditions.
“Abundant sea ice reduces waves and swells and keeps the Arctic Ocean very quiet,” says Robert Headrick, who manages the research programme.
“With increased sea ice melt, however, come more waves and wind, which creates more noise and makes it harder to track undersea vessels.”
Tim Radford, a founding editor of Climate News Network, worked for The Guardian for 32 years, for most of that time as science editor. He has been covering climate change since 1988.
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ARCTIC SEA ICE — Why We Are Losing Arctic Sea Ice
H. Jesse Smith, Science, November 11, 2016: Vol. 354, Issue 6313, pp. 716-717
Summary: Arctic sea ice is disappearing rapidly, leading to predictions of an ice-free summer in the near future. Simulations of the timing of summer sea-ice loss differ substantially, making it difficult to evaluate the pace of the loss. Notz and Stroeve observed a linear relationship between the monthly-mean September sea-ice area and cumulative CO2 emissions. This allowed them to predict Arctic summer sea ice directly from the observational record. Interestingly, most models underestimate this
Abstract: Arctic sea ice is retreating rapidly, raising prospects of a future ice-free Arctic Ocean during summer. Because climate-model simulations of the sea-ice loss differ substantially, we used a robust linear relationship between monthly-mean September sea-ice area and cumulative carbon dioxide (CO2) emissions to infer the future evolution of Arctic summer sea ice directly from the observational record.
The observed linear relationship implies a sustained loss of 3 ± 0.3 square meters of September sea-ice area per metric ton of CO2 emission. On the basis of this sensitivity, Arctic sea ice will be lost throughout September for an additional 1000 gigatons of CO2 emissions.
Most models show a lower sensitivity, which is possibly linked to an underestimation of the modeled increase in incoming longwave radiation and of the modeled transient climate response.
Reference:
Observed Arctic Sea-ice Loss Directly Follows Anthropogenic CO2 Emissions
Dirk Notz and Julienne Stroeve, Science, Nov 11, 2016 — Vol. 354, Issue 6313, pp. 747-750
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Greenland Is Melting – The New Yorker Magazine
Greenland Is Melting: A Song of Ice
From an Article by Elizabeth Kolbert, The New Yorker, October 24, 2016
The shrinking of the country’s ice sheet is triggering feedback loops that accelerate the global crisis. The floodgates may already be open.
When water accumulates on the surface of an ice sheet, more sunlight gets absorbed, which results in more melt, in a cycle that builds on itself. This year’s melt season began so early that many scientists couldn’t believe the data they were seeing.
See this full article here.
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Watch How Quickly Arctic Sea Ice Is Disappearing
From Adele Peters, Co.Exist, November 10, 2016
In September 1984, there were more than a million square miles of thick, older sea ice in the Arctic—an area roughly the size of Alaska, Texas, and California combined. By September 2016, multi-year ice had shrunk to only around 68,000 square miles (a little smaller than Missouri).
All Arctic ice has been steadily disappearing, but the loss of older ice is especially problematic because—as one NASA researcher puts it—it’s an “insurance policy” for the rest of the pack. The less older sea ice remains, the more likely it is that the Arctic could be completely ice-free in the summer.
This older, thicker ice is like the bulwark of sea ice: a warm summer will melt all the young, thin ice away but it can’t completely get rid of the older ice. That bulwark is not as good as it used to be. The older ice is becoming weaker because there is less of it, and the remaining ice is more broken up and thinner.
A NASA animation shows the shrinking ice. The oldest ice is white, while darker colors depict newer ice.
Unlike the massive sheets of freshwater ice in Greenland and Antarctica, melting sea ice won’t make sea levels higher on its own (the ice displaces the same amount of water as it would if it were liquid). But as it melts, and can’t reflect as much sunlight, the more heat the planet absorbs. Rising Arctic temperatures make even more ice melt (including the ice in Greenland), and make the permafrost melt, which releases even more greenhouse gases.
Some researchers predict that the Arctic could be essentially ice-free by the summer of 2017 or 2018.
ACCESS: https://www.fastcoexist.com/3065481/watch-how-quickly-arctic-sea-ice-disappearing
See also: http://www.FrackCheckWV.net
Rapid ablation zone expansion amplifies north Greenland mass loss
Authors are Brice Noël1,*, Willem Jan van de Berg1, Stef Lhermitte2 and Michiel R. van den Broeke1
1Institute for Marine and Atmospheric Research, Utrecht University, Utrecht, Netherlands.
2Department of Geoscience and Remote Sensing, Delft University of Technology, Delft, Netherlands.
Science Advances 04 Sep 2019:
Vol. 5, no. 9, eaaw0123
DOI: 10.1126/sciadv.aaw0123
Abstract — Since the early 1990s, the Greenland ice sheet (GrIS) has been losing mass at an accelerating rate, primarily due to enhanced meltwater runoff following atmospheric warming. Here, we show that a pronounced latitudinal contrast exists in the GrIS response to recent warming.
The ablation area in north Greenland expanded by 46%, almost twice as much as in the south (+25%), significantly increasing the relative contribution of the north to total GrIS mass loss. This latitudinal contrast originates from a different response to the recent change in large-scale Arctic summertime atmospheric circulation, promoting southwesterly advection of warm air toward the GrIS.
In the southwest, persistent high atmospheric pressure reduced cloudiness, increasing runoff through enhanced absorption of solar radiation; in contrast, increased early-summer cloudiness in north Greenland enhanced atmospheric warming through decreased longwave heat loss. This triggered a rapid snowline retreat, causing early bare ice exposure, amplifying northern runoff.
https://advances.sciencemag.org/content/5/9/eaaw0123.full