It’s been a rough summer for the Arctic sea ice. Extent values started off at record low levels during late spring, melt ponding and warming ramped up during early June, and July saw the ice pounded by intense high pressure cells located on the Greenland side.
(Abnormally hot water surrounds the Arctic sea ice on all sides. High sea surface temperature anomalies in this range tend to aid in the maintenance of late season melt momentum. Image source: DMI.)
Warm Waters and Airs
Anomalously warm water invaded from almost every side. The Kara saw extreme sea surface temperature warming after an early ice recession, a flood of warm water from rivers, and a powerful albedo flip to dark ocean from white ice. The Chukchi, Beaufort, and East Siberian seas saw a continued influx of anomalously warm waters from the Pacific side — this flow was fed by the powerful and persistent blobs of warm water in the Northeast Pacific. A heat invasion that has been ongoing for that region since at least Winter. And in North Baffin Bay a pool of anomalously hot water has combined with an extended period of warmer than usual air temperatures to deliver heat to the remaining thick ice along the Northern Greenland and Canadian Archipelago boundary.
Warm Storms Smashing the Old Ice
By August, a series of storms had invaded the Beaufort, Chukchi and East Siberian Seas. Kicking up 20-35 mile per hour winds, they pushed 2-7 foot swells out through an expanding shattered ice zone. Though the storms cooled the air, they tapped heat from the ocean itself through the process of surface churning and the larger dynamic of cyclonic Ekman pumping. All this motion and heat energy created a very unfavorable environment for sea ice — essentially melting the ice rafts out from the water line on up.
(Top [July 22] and bottom [August 4] comparison of the same Beaufort grid showing large rafts of multi-year ice gradually being smashed to finer and finer pieces. Image source: LANCE – MODIS.)
Large pieces of multi-year ice were smashed together like rocks in the late 20th Century video game — asteroids. The ice, ground into ever-finer bits by these storms, then felt the heat of the moving waters and suffered an ongoing dissipation.
The result is that the Beaufort ice is being steadily hollowed out. A bank of thicker ice floes is expanding into the warmer waters of the Chukchi and near-shore Beaufort as it melts. This leading ice edge, though frail, is denser than the interior ice for scores of miles where three large polynyas are in the process of joining into one. If this keeps up for too much longer, the next ten-to-twenty days will see the Beaufort ice and the Chukchi boundary ice practically wiped out.
Melt Invading Past 80 North
Meanwhile, thinned ice and open water is gradually invading the Central Arctic past the 80 North Latitude line.
(Arctic sea ice appears to be in a terrible state in the AMSR2 visible measure. Beaufort and Chukchi ice continues dramatic thinning. Central Basin ice is retreating in numerous places behind the 80 North line. And the fabled Northeast Passage is open to shipping. Image source: Uni Bremen.)
Heat from the Atlantic side is eating away at the ice edge there. Laptev melt is biting in beyond the 80 North line. And the Beaufort storms are basally melting and dispersing the Central Arctic boundary ice. As a result, the monitors are showing sea ice that looks to be in a very unhealthy state overall. The Northeast Passage is open and the Northwest Passage appears to be just a week or two behind.
The Rebound is Wiped out in all Major Monitors
As a result of all this punishment, the sea ice monitors are looking increasingly bleak. Japan’s JAXA extent monitor is showing sea ice boundary measures in the same range as third lowest year on record — 2011. The National Snow and Ice Data Center measure is not too far behind at just a hair above 2011 and 2010 — now tracking at 5th lowest extent on record (a loss of two places since last week). These extent measures are swiftly catching up to the Cryosphere Today area totals that are now also just a hair above 2011 at 4th lowest on record. The area measure is also interesting in that overall area is at 4.13 million square kilometers — which is now starting to dip below the 2005 line.
But perhaps most concerning of all is the fact that sea ice volume, which showed a brief bounce back from 2012 record lows during 2013 and 2014, is now re-entering decline. For According to PIOMAS, the ongoing punishment we have visibly seen in the form of high atmospheric temperatures north of the Canadian Archipelago and in remaining thick ice being swept into the billiards pool that is the Beaufort has pushed that volume measure well below the 2014 line and back toward recent record low years.
(PIOMAS volume measure takes a nose-dive in July. Continued losses at this rate would put sea ice volume in the range of lowest years recently observed. Image source: PIOMAS.)
It’s a steep nose dive. One that will start to challenge the upper boundary of record low years without a slowing in the rate of losses soon.
Storms, Ocean Surface Warmth, El Nino Heat Transport, and Beyond 80 North Melt Drive Late Season Loss Risk
With a month and a half of melt still to go, we could see a softening in this high rate of loss and an adjustment that brings use closer to 2014 for end season. Or we could see the steep rate of loss continue to challenge the 2011 boundary in some measures and possibly even break lower to challenge 2007. But given the melt momentum coming out of July, it is very unlikely that measures return to 2014 levels. As a result, it looks like the summer of 2015 is wiping out the post-2012 sea ice bounce which, given the massive pace of human-forced warming and failing to see large enough melt from Greenland to counter that trend in the Arctic, appears to have been inevitable.
Looking forward there appears to be four factors that will play out their final hands for 2015 melt. The first are those very warm sea surface temperatures we mentioned earlier. The second is the fact that this is an El Nino year featuring a very warm Northern Pacific and a strong northward heat transport through the Canadian Archipelago and Alaska. The third involves the weak sea ice and persistent storms in the Beaufort, Chukchi, and ESS. And the final major factor involves the strong advancement of melt into the Central Arctic and the higher likelihood that the below 80 North boundary ice will be wiped out in the coming weeks.
(The northward propagation of anomalously warm ocean surface waters is bad news for late season sea ice. Extremely warm Northeastern Pacific surface waters and an associated El Nino warming of the Eastern Pacific equatorial waters creates a pathway for warm air transport into the Arctic over Alaska and Canada during late summer. Such a situation may result in an extension of late season melt beyond the September 15 date. Image source: NOAA ESRL.)
Abnormally warm sea surface temperatures plus the atmospheric feedback of El Nino hint that more energy to melt ice may remain in the Arctic for longer than during a typical year. Current transport of that abnormally warm water into the Chukchi, East Siberian Sea, and the Beaufort will continue. And the El Nino tendency to push warm air up over Alaska and the Bering will be reinforced by the strong warming in the lower Chukchi. These factors will tend to extend late season melt. Over on the Atlantic side, a similar dynamic is starting to come into play. Warm waters in the Laptev and Barents are increasingly being driven against the edge ice past the 80 North boundary line by warm southerly winds and through the action of storm systems invading the upper North Atlantic. Over the past few days a pattern has emerged in the models indicating an influx of these storms past Iceland and into the Barents near Svalbard. Swell propagation and warm water driven north will have a deleterious effect on the ice there.
As storms rise up from the North Atlantic, storms are predicted to continue to plague the ice in the Beaufort, Chukchi and East Siberian seas. According to GFS model runs, this tendency continues through at least the next five days. And with warm air firmly in place over Alaska and the Chukchi, while cooler air sits over the Beaufort, the gradient necessary to fuel these storms will remain in play. Ocean state forecasts pick up seven foot swells in the East Siberian Sea tomorrow, nine foot swells in the Chukchi on Friday, and 3-4 foot swells ranging the thick ice billiard room in the Beaufort on Sunday. Swells in the Laptev open water are also predicted to hit 6-7 feet over the coming days.
Stepping back and looking at the overall distribution of the sea ice, we find that much of the beyond 80 North region is invaded by melt. A substantial amount of weak boundary ice remains in the Beaufort, the Chukchi, the East Siberian Sea, near the land regions of the Laptev, and within the waterways of the Canadian Archipelago. Ice in these outlier regions is traditionally more vulnerable to rapid melt and it is doubtful that much of it will remain by end season.
(Arctic Ocean sea ice extent measures are tracking in the range of 2012 according to the above graph by Wipneus. Low values that, entering final stage melt for August and September, may swing the overall measures lower come end season. Image source: Wipneus.)
Meanwhile, the beyond 80 North melt invasion is substantial to the point that we are now very close to the 2012 melt trend line in that key region. In fact, pretty much all the interior Arctic Ocean seas show extent values tracking near the 2012 record low line.
These low Arctic Ocean values imply a deeper vulnerability to hitting lower end season totals. A vulnerability the overall measures, so far have missed.