Those-who-wish-the-sea-ice-to-melt have been alarmed by an apparent unexpectedly early end to the melt season. If course, everything alarms some of them, so what can I say?
The swift regrowth of ice actually should have been expected, because the remaining ice was sprawled out over a much larger area than the ice was in the record-setting year of 2012. It didn’t show up in the “area” graphs, because all the holes in the ice were subtracted. In term of pixels, the area was not as large as it was in fact. Fact? Well, I suppose that depends on what your facts are. You decide. The maps are below. 2016 is to the left, 2012 to the right.
My own view is that, because 2016 is sprawled over a larger area, and because that creates more edges, and because new ice grows best out from the edges of existing ice, (chilled, open salt water often sinks before it can freeze and float), the many edges will accelerate the growth of new ice.
Often ice-melt continues well into September, due to “basal melting”, which is ice melted from the bottom even when the air above is below freezing. This usually involves thin pans of slushy ice. The storms (“Ralph”) already smashed up the more flimsy pans of ice this summer, which leads me to believe we won’t see them melt, because you can’t subtract what you don’t have. Also, because melting ice uses up a lot of available heat, turning it into latent heat, I imagine the churned waters are colder between the bergs, which will speed the refreeze, (even though the latent heat becomes available again as the water refreezes.)
The thickness of the ice seems greater than the above maps suggest. The NRL map has to average out the chunks of thick ice and the spots of open water, and therefore chunks of ice 8 feet thick floating in open water (0 feet thick) will average out as ice 4 feet thick.
Be that as it may, the ice is definitely battered and shattered. It is a process that has been going on since last Christmas. An overview is helpful.
At the end of last year the Pole had chilled to -30°C, and colder, and sea-ice was thickening fast. In fact it was the only time temperatures were below normal all winter, as a rush of milder air surged north in time for Christmas.
Temperatures actually touched freezing for a few hours at a buoy near the Pole, and this of course offered an opportunity for the usual suspects to write headlines about Santa facing an ice-free Pole, and Rudolph drowning, though the air was back below freezing hours later, and the mild air masses lost heat at the surface with remarkable speed. (Likely the mild air rose like a hot air balloon, fueling a low pressure system which, with 20-20 hindsight, I recognize as “Ralph”.)
While there was much ado about the warmth at the Pole being a sign of Global Warming, I myself wondered how it could warm the planet to have so much heat sucked up and basically lost to the sunless arctic night. It was like having the chimney’s flue wide open, and the whirl of low pressure reminded me of the whirlpool over a drain.
In terms of sea-ice there seemed to be compression at the Pole, and of course there could be no melting with temperatures well below zero. However as the winter passed the infrared views of the total darkness showed the distinctive black lines of heat made on the white (cold) surface of ice, which indicate open leads of sea-water have formed in the ice. These black areas grew milky-colored as they froze over, but again and again the ice would crack as the winds roared. This was especially true on the Pacific side in the Beaufort Sea.
(Having the arctic air exposed to open water measuring +29°F rather than sea-ice chilled to -31°F would seem to add heat to the arctic temperatures, and the arctic temperatures were the reason the past year is called the “hottest ever”. [We are unable to add Arctic temperatures to the unbelievably hot Dust Bowl years, because there were no thermometers out on the ice back then]. This should give thinkers pause.)
On the Atlantic side the rushes of mildness north pushed the ice backwards in Fram Strait. The ordinary flushing of ice down the east coast of Greenland was impaired, keeping thicker ice north but lowering the “extent” and “area” graphs. When ice did start south it often was blown across Fram Strait by west winds, into a mild tendril of the Gulf Stream that curls around the west side of Svalbard.
The ice then melted swiftly, but the northbound current was also significantly cooled, and it was made less saline as well. This alters the location it dives beneath the arctic waters, and led to all sorts of interesting speculation about the Gulf Stream slowing down and so forth, which is wonderful to wonder about.
By spring the sea-ice was a mess. As the Russians prepared to open their yearly Barneo blue-ice jetport they had problems finding any ice smooth enough. The best way to envision the state of the ice is to watch a video from the cockpit of a jet that did land, just before a new crack on the runway (that the jet avoids) closed it down for a time.
Also of interest was the reports of the skiers doing the “final degree” challenge. They complained about leads of open water (though not as much as they complained about leads in the higher-ice year of 2006) and fought through mini-mountain-ranges of pressure ridges.
All the while I kept noting “swirls” at the Pole. (I hadn’t named “Ralph” yet). Even when there wasn’t much of a low pressure to see at the surface, they would show up in the temperature maps. April 9 to right; April 26 to left.
April was actually the lone time high pressure came close to pushing “Ralph” from the Pole, and becoming a textbook “Polar High”. Low pressure was relegated to the Atlantic side, as strong high pressure grew over the Beaufort Sea, ripping the ice away from the Alaskan and Canadian coasts, and forming textbook Polynyas.
This open water along the North American coast seemed to be an early start to the melt-season, and gave those-who-want-the-ice-to-melt high hopes. The belief was that the open water would absorb sunshine and warm. In actual fact the winds were still below freezing, and the open waters were chilled and even formed a fleeting skim of “baby ice.” Later on in the summer the open water was warmed by the higher sun, as it always is, but the jury is still out about whether the cooling outweighed the warming, or vice versa.
The point I want to make is that the Pole was bashed and battered even before the melting began this summer, and that there are areas of open water even now which have much to do with “Ralph’s” gales, and little to do with sunshine and melting. It is my belief we are witnessing a very different situation than our experience is able to draw from. Our earliest satellite records only go back to 1970, and, in terms of a cycle that is roughly sixty years, we may well be witnessing 1959. Rather than behaving as if we are authorities we should be humbly watching like the students we truly are.
For the record, here are the recent maps:
When we last kept notes “Ralph” was sulking down in the Canadian Archipelago. He was receiving some reinforcements (R20) from the Atlantic over the top of Greenland, and perhaps some modified Pacifc air through Canada, but was largely cut off from support. Most energy was sucked up by big gales by Iceland, and I found it interesting and surprising that Ralph didn’t fill and fade, but instead persisted north of Canada. In the final maps Ralph is energized by R21 coming up through Canada, and models suggest he will be further energized by the Icelandic low breaking free and coming up the east coast of Greenland, (R22,) and by tomorrow (Thursday September 15) we will again see the all too familiar sight of Ralph reincarnating over the Pole.
(Missing September 8 maps)
The fuel for the next incarnation of “Ralph” perhaps can be seen by the rise in polar temperatures. What will be interesting to watch is whether the next incarnation “creates cold”.
UPDATE: Ralph is back.