A lot of attention has been paid to a ‘Blob’ of unusual warmth at the ocean surface in the Northeastern Pacific. And for good reason, for that Blob of human-warmed water has had wide-ranging negative impacts on both weather and sea life. Now there’s a second hot Blob forming in the Bering and Chukchi seas. One that may also have some rather significant effects as the summer of 2015 continues.
Abnormally Warm Waters Running Toward the Sea Ice
Hot Blob #2 is a vast stretch of warm water covering the Bering and Chukchi seas between Alaska and Kamchatka (Neven, in his most recent sea ice summary, touched on this building warm water zone here). It encompasses surface waters in an usually frigid region that now feature temperatures ranging from 3 to 5.5 degrees Celsius above normal. Covering an area roughly 800 miles in diameter, this pool of outlandishly warm ocean waters is being fed by currents running up from the south and by heat bleeding off Alaskan and Siberian land masses. In this case, land masses that are also experiencing record heat.
(Hot Blob #2 forms in the Bering as its warm waters are swept north toward the Arctic sea ice pack. The above sea surface temperature anomaly map shows a broad stretch of much hotter than typical surface waters being pulled poleward by prevailing ocean currents. Image source: Earth Nullschool.)
Though the abnormal warmth is also likely fed by a powerful albedo switch from white, reflective sea ice, to dark, sunlight absorbing ocean, other factors associated with El Nino and related to the hot blob off the North American West Coast are also likely in play. And of particular interest in this present extreme hot water situation are currents flowing northward out of these warm pools and directly into the Arctic. Currents that have been eating away at the ice since winter.
One warm water bearing current — the Alaskan Coastal Current — runs directly out of the abnormally hot surface zone in the Northeastern Pacific (Blob #1). This current flows along the North American Continental Shelf, out past the Aleutian Island Chain and finally up into the Bering Sea. A second current — the Siberian Coastal Current — feeds into the Bering from the Asian Continental Shelf. These currents then combine and push Bering Sea waters on through the Bering Strait and up into the Chukchi Sea.
(Algae blooms, like this one in the Chukchi Sea just south of the ice pack, have been a common feature of the Pacific Ocean hot pools. The warmer waters are a preferred environment for microbes which can see some amazingly rapid population explosions. If the blooms become too numerous they can rob the ocean surface waters of nutrients and die off en masse. The decay of dead masses of algae can then leech away the oceans’ life-giving oxygen, setting off and contributing to a chain of harmful ocean anoxia. In a warming world, this process, combined with disruption of ocean currents and the basic fact that warmer waters bear less oxygen in solution, is a major contributor to mass extinction events. Image source: LANCE MODIS.)
Northward propagation of these currents during spring and summer plays a critical role in the rate of sea ice recession in the Bering, Chukchi, Beaufort and East Siberian Seas. Waters warmed by the summer sun and by the more rapidly heating continents amplify in the Bering Strait before making contact with the sea ice and pushing it to melt and recede.
Impacts Already Visible Up the Coast
This year, waters in the Strait are extraordinarily warm — measuring 5.4 degrees above normal surface water temperatures. A plug of 5 C + above average water entering the Chukchi, Bering, Beaufort and East Siberian seas at a time when solar insolation is hitting peak intensity and during a period when nearby Arctic regions like Alaska are experiencing some of their hottest temperatures ever recorded. These waters, at temperatures in the range of 7-8 degrees Celsius, are warm enough to rapidly melt any ice they contact. And they’re flooding directly toward the ice pack.
(Ice rapidly melting off of Barrow, Alaska on June 23, 2015. Ice is seen receding from the near shore zone even as the ice pack further out breaks into dark blue patches of open ocean. Image source: Barrow Ice Cam.)
Unusually warm surface water and air temperature impacts can already be seen further down the coast in places like Barrow, Alaska. Today, near shore sea ice dramatically melted and off-shore sea ice has retreated poleward — revealing the tell-tale blue of open ocean in the distance. An extreme one day change for Barrow sea ice, which only featured melt ponds and some near-shore melt 24 hours before.
Conditions, Model Runs Point Toward Substantial Thinning
Looking northward, we find ice pack conditions showing substantial thinning, significant melt pond formation over the surface ice and increasingly disassociated ice flows in the Beaufort, Chukchi, and East Siberian Seas. Near shore ice in the East Siberian Sea (ESS) has taken on a vivid blue or glassy appearance indicative of melt pond formation. Melt and compaction wedges have formed in the ESS along an axis pointing toward the pole. In the Chukchi, sea ice recession and thinning appear to be proceeding quite rapidly, while dispersing ice in the Beaufort is hitting warmer surface waters, fed by Mackenzie River outflow, and melting.
(The ARCc model run shows rapid thinning in the Beaufort, Chukchi and ESS through June 30. Image source: US Navy.)
The Navy’s ARCc historic and forecast model run for May 30 through June 30 shows rapid thinning of sea ice in the affected regions. The forecast run for the next seven days shows extreme thinning continuing through the ESS and Chukchi, with thicker ice in the Beaufort also experiencing substantial reductions (Note that the Navy’s GLBb model runs look even worse).
Overall, given the fact that storms are now ranging through substantial sections of the Arctic, pushing for more sea ice dispersal, losses will tend to show up more in the sea ice area and volume measures first. Dispersal will also tend to mute extent losses for a time. Given the delay in area and volume tracking, it’s likely that overall impacts to sea ice will tend to be muted in the measures over coming days with a clearer signal showing up by late June and early July. But despite these underlying and complicating weather conditions, the fact remains that a lot of unusually warm water is heading northward toward the ice, with likely greater impacts to follow.
Hat Tip to Colorado Bob
Hat Tip to Ouse MD