Another blip has appeared on the DMI “extent” graph.
Upticks in “extent” such as this in August do not indicate any new sea-ice has formed. (As can be seen by referring to “volume” graphs.) Rather it tends to indicate sea-ice has spread out. “Extent” measures sea-ice without specifying how concentrated it is; a square km is a square km, whether the concentration is 100% or 15%. Usually sea-ice of concentrations less than 15% are defined as “open water” even if the concentration is 14%. Therefore it can be seen that, should winds push ice into open water, there can be an uptick in “extent” as the concentrated sea-ice is dispersed. I think the current uptick is due to north winds pushing sea-ice into the ice-free Laptev Sea.
As the shallow waters of the Laptev Sea have been warmed by the summer sun, the sea-ice shifted into those waters should swiftly melt as the waters are cooled. Those waters are five degrees above normal, according to the NOAA sea Surface Temperature Anomaly map.
I have a bit of a problem with the modeling NOAA uses, for at the center of the above map you will notice the deep, nearly-brown red actually touches the sea-ice. This is actually a physical impossibility, for the temperature of ice water, by definition, is the freezing point of that water, depending on how much salt it contains. For ice-water to be five degrees above normal means “normal” is water five degrees below freezing, which would be ice. See the problem?
What the edge of the ice should look like is how the south of Hudson Bay looks, as the last bits of ice melt away. Until the ice is gone the water, by definition, must be at freezing. The Canadian ice service shows ice remains, though it is melting fast.
And here the NOAA SST anomally map does show waters right at freezing, (or just below, as salt-water freezes at colder temperatures.)
Another place where the model’s output is questionable is along the coast of Newfoundland, where the sea-ice has retreated north but the icebergs still come south. Here is a good picture to demonstrate the difference between sea-ice and icebergs:
Sea-ice tends to be one to as much as nine feet thick, but icebergs can be gigantic, hundreds of feet thick.
Though the sea-ice has melted north, the icebergs are still coming south.
The icebergs do not show up on “extent” maps because they represent less than 15% (or even 1%) of the surface, but there are many of them even in the summer. To avoid a repeat of the Titanic, the movement of these icebergs must be tracked and charted.
Greenland must shed these huge bergs because more snow falls on its icecap than summer can melt. In fact, the past two summers melted even less snow than normal.
The above graph measures in gigatons, which is a colossal unit of measurement. A gigaton is 2.2 trillion pounds of water. (2,200,000,000). If you want to alarm people just mention that on a warm summer day the edges of Greenland shed 8.8 trillion pounds of water. Yet that is only a drop compared to what it loses in an entire summer, and in a summer only a third of what falls as snow is able to be melted (except on an exceptional year like 2011-2012.) What becomes of the other two thirds? It flows off Greenland as glaciers.
The size of these glaciers boggles the mind. When some of the icebergs break off the icecap at the edge, the land literally springs upwards, relieved of the weight. Earthquakes range as high as 5.0 on the Richter Scale, and can be seen on seismographs on the far side of the planet. Every summer roughly 4,400 trillion pounds of ice must be shed by Greenland just to achieve a balance, and all this ice comes floating south, down the east coast of Greenland and west coast of Baffin Bay. Each berg, and especially the larger icebergs, has a mini ecosystem all its own surrounding it. Sailors describe how they each have a cooler pocket of air around them and sometimes their own fogs, and each creates its own freshwater lens atop the saltier sea. With “sails” extending up over a hundred feet and “keels” down nine hundred, they can gouge coastal sea-bottoms and move contrary to currents, and stir the water like gigantic spoons, and when the bottoms melt more swiftly than the tops they can capsize with tremendous churning and splashing. Remembering that we are talking about 4,400 trillion pounds, just imagine the mess their magnitude, independence and variability makes of any attempts to model sea-surface temperatures along the northern edge of the Gulf Stream! Largely I think it best to use present tense satellite data and not attempt to chart the complexity, though the mortal mind loves to wonder about such things.
Yet all this is going on unseen by NOAA SST anomaly maps. Not that I don’t value the maps, and refer to them constantly, but I recognize their limits.
One final thing I notice in the maps is that it is colder than normal up in Bering Strait.
This anomaly in Being Strait likely is due to the cold PDO and La Nina, and may be indicative of colder than normal water flowing into the Arctic Sea, which could, (I hypothesize), preserve sea-ice blown into open water, or at least slow its melt. Where I usually regard blips in the “extent” graph in August with skepticism over their ability to predict any true increase in “extent” levels, and indeed think they often indicate a mass of ice will be melted more quickly because it is shifted into warmer waters, I am not so sure of myself this year, and am keeping one eyebrow quirked.
Stay tuned.
Sunrise's Swansong 