jack, that 'archived heat' article is a stunner, especially the conclusion.
there is enough heat to entirely melt the sea-ice pack that covers this region for most of the year
There has been much disagreement around here over the years about how soon there could be a year-long (or nearly year long) ice free (or nearly ice free) Arctic Ocean, with many people say ing that a (nearly) year-round Blue Ocean Event would be decades to centuries away, if it ever happens at all.
This study, though, is saying that it could basically happen any time, given the right conditions. Presumably those conditions would look something like the Great Arctic Cyclone (GAC) of 2012, or perhaps something even stronger, that would both break up the weak and thin ice and also create waves big enough to stir up this deeper, hotter (and saltier) water.
Wow!
I'd love to hear what others have to say, and if this study is changing some peoples minds about when we may have year-round ice-free Arctic Ocean (or something quite close).
Below I quote the discussion part of the study. There are two threads in that discussion (it seems to me)..
Heat will continue to accumulate at depth especially with more open water in the Chukchi during the high insolation period in summer As a result, there will be more heat coming up all year round,
reducing winter ice growth. The study does not suggest a sudden event when 30 years worth of accumulated heat suddenly burps to the surface and poof, no ice. (See the last sentence in the extract below).
If surface water temperature in the Chukchi reaches, say, 13 celsius, the density of this salty water will drop and subduction under the cooler fresher water would stop.
It adds to my and others speculation that it is winter sea ice that is going to be strongly reduced as in the last 2 years. But if subduction stops ?
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EXTRACT FROM THE STUDY
DISCUSSION
Implications and outlookThe doubling of BG halocline heat content over the past three decades
appears attributable to a warming of the source waters that ventilate the
layer, where this warming is due to sea ice losses in the Chukchi Sea that
leave the surface ocean more exposed to incoming solar radiation in
summer. The effects of an efficient local ice-albedo feedback are thus
not confined to the surface ocean/sea ice heat budget but, in addition,
lead to increased heat accumulation in the ocean interior that has
consequences far beyond the summer season.
Strong stratification and weak mechanical mixing in the BG halocline ensure that significant
summertime heat remains in the halocline through the winter.With continued sea ice losses in the Chukchi Sea, additional heat may continue to be archived in the warm halocline. This underscores the far-reaching implications of changes to the dynamical ice-ocean system in the Chukchi Sea region.
However, there is a limit to this: Once the source waters for the halocline become warm enough that their buoyancy is affected, ventilation can be shut off. Efficient summertime subduction relies on the lateral surface front in the NCS region between warm, salty water that is denser to the south and cooler, fresher water that is less dense to the north. For longer-duration solar warming (that is, longer-duration ice-free conditions in the region), SSTs on the south side of the front may become warm enough (around 13°C, under the assumption of a 1.5-month ice-free period dominated by solar absorption) that the lateral density gradient is eliminated.
It remains to be seen how continued sea ice losses will fundamentally change the water column structure and dynamics of the Arctic halocline.
In the coming years, however, excess BG halocline heat will give rise to enhanced upward heat fluxes year-round, creating compound effects on the system by slowing winter sea ice growth.