Friday, 19 August 2016

Arctic storm continues to shread thin ice

Warm Arctic Storm Tearing Sea Ice to Shreds amidst Big 2016 Heat Spike


19 August, 2016
Abnormal. Unprecedented. Remarkable. Extreme. These words are supposed to describe unusual events, but in the weird world we’re now entering, the extreme has become commonplace. Some people call this emerging state of affairs ‘the new normal.’ A more direct descriptor is ‘spiraling into climate chaos.’
Chaos is an apt word to describe the scene in the Arctic this week as one of the most powerful summer cyclones ever to form rages in a place that has just experienced a record-shattering influx of atmospheric heat. This storm is hammering the sea ice, pushing it nearly to the second-lowest extent on record. But worse may be still to come as a very weak and diffuse ice pack is predicted to face off against a storm that’s expected to significantly reintensify on both Friday and Tuesday.

Record Arctic Heat

The Arctic. It’s a place we typically associate with frozen things. Due to the billions and billions of tons of heat-trapping gasses dumped into the atmosphere each year by burning fossil fuels, now it’s a place that’s thawing at a disturbingly fast pace. The region could best be described in these few words — record abnormal warmth in 2016.

(This graphic from University of California, Irvine Ph.D. candidate Zack Labe is a visual measure of a stunning jump in Arctic temperatures for 2016. So much heat in the Arctic has profound implications, not just for the Arctic ice and environment, but for the rest of the world as well. In other words — warming that happens in the Arctic doesn’t stay in the Arctic.)

So far, 2016 has seen temperatures in the Arctic that are well above the warmest previous year ever recorded. This big spike in a decades-long trend includes, for this single year, about 35 percent of all the temperature rise experienced there since the late 1940s. It’s like taking more than a third of all the warming in the Arctic seen over the past 68 years and cramming it into just one year. It’s insane.
The Warm Storm Generator

Heat in the Arctic doesn’t just emerge there. It comes, largely, in the form of energy transfer.
Heat-trapping gasses warm the atmosphere in an uneven fashion. The way these gasses absorb solar radiation results in more heat trapping during the dark of night. And the Arctic experiences a thing called polar night which lasts for months.
As a result, the Arctic already gets a slightly more powerful nudge from global warming than the rest of the world. As the cold begins to fail in the Arctic, a number of amplifying feedbacks come into play that further multiply the warmth.
image
(A dance of cyclones. GFS model rendering by Earth Nullschool shows a strong influx of heat from the Eurasian Continent and the Barents and Kara Seas feeding into a bombing low-pressure system on Monday at 12:00 UTC. The low is predicted to meet up with the currently raging Arctic cyclone by late Monday or early Tuesday. Combined, these lows are expected to drop into the 960s to 970s mb level, extending the scope of the strong event and possibly resulting in the most powerful cyclone ever to have formed this time of year in the Arctic Basin. Image source: Earth Nullschool.)

As the Arctic heats up, its natural barriers to heat coming up from the ocean or from the south begin to fail. The more evenly-warmed surface of the ocean transfers some of its heat north and pumps this added energy into the Arctic air. The lower sea-ice levels cause this water to warm even more, its dark surface trapping more of the summer sun’s warmth than the white ice ever could.
The polar Jet Stream begins to weaken as the relative difference between Arctic and lower-latitude temperatures drops. In the Jet Stream’s meanders, strong warm winds blow in from the ever-hotter continents and ocean surfaces of the mid and upper latitudes.

It’s a simple physical property of the atmosphere that burgeoning heat often seeks out the cold. It rises as it flows toward the Pole, and when it collides with these chilly pockets, the result can be an atmospheric maelstrom.
The Great Arctic Cyclone of 2016 Smashes Sea Ice

Such was the case earlier this week as a warm tongue of air flowed up into area of the Laptev Sea from Siberia. This warm flow tapped moisture from the Kara and Barents Seas and fed into a developing storm system (see article here). Pressures at the storm’s center rapidly fell and by late Monday, August 15th, had dropped to 966.5 millibars. The result was one of the strongest cyclones ever to form over the Arctic Ocean during August.

(We’ve probably never seen the ice so thin near the Pole during August. Zack Labe‘s rendering of SSMIS sea ice concentration measures from late July to August 17 shows a stunning degree of thinning and loss. Note the large, low-concentration holes opening up near the Pole in the final few frames.)

The storm rampaged through the Arctic. Pulling in strong winds and heavy surf, it smashed the sea ice, driving daily extent losses to 110,000 square kilometers on Tuesday and greatly thinning a vulnerable tongue of ice running out toward the Chukchi Sea. Meanwhile, near the Pole, great gaps 50 to 100 miles wide have opened up, revealing water that is 80 percent clear of ice.

The storm subsequently weakened, with pressures rising today into the 985 mb range. But over the next few days, the system is predicted to reintensify — first on Friday to around 971 to 978 mb as it approaches the Canadian Arctic Archipelago, and then again on Tuesday to around 963 to 976 mb when it loops back toward the Laptev.
Central Arctic Basin Sea Ice lowest Ever Recorded
(AMSR2 and SSMIS sensor reanalysis shows that 2016 Arctic sea ice area [black line] in the Central Arctic Basin — a key region for indicating sea ice health — hit new record lows over recent days. A signal that a challenge to 2012 records could emerge over the coming days as the 2016 cyclone is expected to re-intensify. Image source: The Great White Con.)

In each case, the storm is predicted to draw on heat, moisture, and low-pressure cells riding up from the south, with the first stream of energy feeding into this low from over the Beaufort and Bering Seas and northeastern Siberia, and the second running up from the Barents and Kara Seas, western Siberia and northeastern Europe (you can see the succession of lows and moisture here in this model run by Climate Reanalyzer).

If this happens, we’ll be coming out of a situation where a warmth-fueled Arctic cyclone will have bombed to record or near-record strength on two to three separate occasions, all the while applying its buzz-saw winds, waves and Coriolis forces to the sea ice — a full-blown nightmare Arctic sea-ice melt scenario in the midst of a record-hot year.
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Hat tip to DT Lange
Hat tip to Colorado Bob
Hat tip to Bill h


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