See Canada's glaciers while you still can. Their melting is irreversible, according to projections based on real-world data and validated by satellite images.
By the end of the century, a fifth of the Canadian ice sheet – the world's third largest – could be gone for good, raising average global sea levels by 3.5 centimetres.
If the whole ice sheet melts, it would raise the global sea level by about 20 centimetres, a fraction of the 70 and 7 metre rises expected respectively if Antarctica and Greenland each shed all their ice.
The Canadian melt seems paltry in comparison, but it becomes significant when the effects of other smaller ice fields melting are taken into account, says David Vaughan, leader of ice2sea, the European Union programme that supported the work.
"Most attention goes out to Greenland and Antarctica, which is understandable because they're the two largest ice bodies in the world," says co-leader of the study, Michiel van den Broeke of Utrecht University in the Netherlands. "But with this research we want to show that the Canadian ice caps should be included in [sea level] calculations."
In 2012, slightly-above-average winter accumulation in the Alps was offset by extreme summer ablation, yielding mass balances that were negative. In Austria, Mullwitzkees had a mass balance of -1461
mm w.e. and Hallstätter Gletscher a mass balance of -1944 mm w.e. (Fischer 2012). The Austrian Glacier inventory in 2011 examined 90 glaciers: 87 were in retreat and 3 were stationary. Average terminus change was -17 m, reflecting the continued negative mass balances of the region. In Italy, a large deposit of World War I ammunition melted out of the glacier on Ago Di Nardis Peak during August 2012. The Swiss Glacier Monitoring Network noted in 2011 92 glaciers retreating, 1 advancing, and 3 stationary. The one advancing glacier had retreated the previous five years. The 2012 data are not complete, but retreat was again dominant.
In Norway, terminus fluctuation data from 25 glaciers for 2012 with ongoing assessment indicate 21 retreating, 2 stable, and 2 advancing. The average terminus change was -12.5 m (Elvehøy 2012). The retreat rate is less than 2011. Mass balance surveys found deficits on all Norwegian glaciers.
In the North Cascades, Washington La Niña conditions during the winter led to a wet winter and a cool and wet spring. Summer was drier and warmer than normal. This led to nearly equilibrium conditions on North Cascade glaciers, with mass balance positive on five glaciers and negative on four glaciers (Pelto 2013). In southeast Alaska, the same La Niña conditions prevailed and led to the highest snow totals in several decades. Glacier snowlines were more than 100 m below average on Lemon Creek and Taku Glaciers of the Juneau Icefield indicative of moderate positive mass balance (Pelto 2013).
Alfred Tennyson wrote:We are not now that strength which in old days
Moved earth and heaven, that which we are, we are;
One equal temper of heroic hearts,
Made weak by time and fate, but strong in will
To strive, to seek, to find, and not to yield.
Newfie wrote:Saw Extreme Ice last year at a movie hall.
Now on Internet. Good flic.
http://video.pbs.org/video/1108763899/
An international team led by glaciologists from the University of Colorado Boulder and Trent University in Ontario, Canada has completed the first mapping of virtually all of the world's glaciers—including their locations and sizes—allowing for calculations of their volumes and ongoing contributions to global sea rise as the world warms.
The total extent of glaciers in the RGI is roughly 280,000 square miles or 727,000 square kilometers—an area slightly larger than Texas or about the size of Germany, Denmark and Poland combined. The team estimated that the corresponding total volume of sea rise collectively held by the glaciers is 14 to 18 inches, or 350 to 470 millimeters.
The new estimates are less than some previous estimates, and in total they are less than 1 percent of the amount of water stored in the Greenland and Antarctic ice sheets, which collectively contain slightly more than 200 feet, or 63 meters, of sea rise.
Graeme wrote:phys.org
"A lot of people think that the contribution of glaciers to sea rise is insignificant when compared with the big ice sheets, ... But in the first several decades of the present century it is going to be this glacier reservoir that will be the primary contributor to sea rise. ..."
To better characterize recent changes to the Columbia Glacier, Ryan Casotto (University of New Hampshire) and colleagues used ground-based radar to measure the glacier's speed every three minutes for eight days in early October 2014. Preliminary results show that both the West Branch and the East Branch (which feeds into the Main Branch) are now moving between 5 and 10 meters (16 and 33 feet) per day. That's slow for Columbia, but fast compared to other glaciers.
Meanwhile, the area of the Main Branch hasn't changed much since 2012, but this part of the glacier is changing in other ways. The October 2014 field research found a connection between the motion of the Main Branch and the region's tides.
"That tells me that the glacier has thinned so much now and has very little traction against the bed, so that even the up and down tidal motion changes how the glacier is flowing," O'Neel said.
The tides are affecting the glacier as much as 12 kilometers (7.5 miles) upstream. The tidal effect only dissipates where the glacier bed rises above sea level and the ice-ocean connection is lost.
"This behavior makes us think that the Main Branch is once again unstable and possibly due for an episode of very rapid terminus retreat,” Pfeffer said. “It's hard to say how soon or likely that retreat is, however, and we've been surprised before."
Alfred Tennyson wrote:We are not now that strength which in old days
Moved earth and heaven, that which we are, we are;
One equal temper of heroic hearts,
Made weak by time and fate, but strong in will
To strive, to seek, to find, and not to yield.
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