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Pekka Kostamo
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The UN Environment Program (UNEP) has recently published a review document targeting the general public and decision makers on the permafrost issue.
Thank you Chris. In the meantime I found a summary of the Arctic Ocean stratification issue in: This 1991 paper by Rudels, Larsson and Sehlstedt discusses in considerable detail the temperature and salinity structure and its transformations during the freeze-thaw cycle. Another complicating factor is apparently that extensive areas are very shallow and therefore the processes are not the same in different parts of the ocean. Medium salinity and relatively warm surface water is siphoned off the Northern Pacific by way of the shallow (50m) Bering Strait. It forms a distict layer below the topmost mixed layer. In open sea conditions these layers develop a stronger interaction, driven by wind effects. I guess my main point is that there is a major difference between the physical processes that exist in an ice covered or an open ocean, in addition to quite different sea/atmosphere interfaces.
Pondering the Arctic sea ice, a couple of observations. First, there is a disparity between winter and summer "melts". The winter ice maximum develops in northern Atlantic and Pacific waters, not within the Arctic Ocean proper which is frozen over all winter. Different and independent environments altogether as to salinity, stratification and sea currents. There is a decline in extent winter ice, but it is small and appears to reflect the general warming trend. The summer minimum is drastically more pronounced. It happens in the specific circumstances of the Arctic Ocean. It also repeats, so some form of memory must be involved. A clear "mode change" in the process has appeared. The Arctic Ocean is a rather closed basin with its own dynamics. It used to have all year ice cover. Wind drag was minimal, which resulted in slow currents and little mixing, strong stratification of waters. Below ice, the uppermost layer used to be a thin (20 meter) layer of very low salinity water, generated by the annual ice surface freeze-thaw cycle and inflow from the several big rivers. (Below it, layers of higher salinity and also warmer Pacific and Atlantic waters) Even a short impulse like the one seen in 2007 allows the winds to break the stratification. Repairing the low salinity layer is a slow process. This may be the observed memory fuction. Freezing is of course a function of both water salinity and temperature. In my view, stored heat can not alone provide the memory function we observe over the past 6 years. Maps of long term surface salinity change, anyone? (My 2 cents speculation...)
BlackDragon: Not that I am a scientist on this, but: The Arctic Ocean used to be a very special place where the below-ice and above-ice processes were almost independent from each other. Sea currents were slow and turbulence was little within a rather closed basin. Waters from different origins could be recognized oceanwide. A thin layer of low salinity water produced by inflow from the great rivers and the freeze-thaw process of ice stayed above a layer of medium salinity Pacific water siphoned off from the Bering sea by way of the shallow Bering Strait (depth 150 ft). Bottom water was of Atlantic origin and had highest salinity. Open water means a whole new game. It very much strengthens the many couplings at the surface. Winds cause stronger and more variable currents and turbulent mixing increases in the uppermost layers. A special place becomes just another ocean...
Superman: "The IEA is a forty year old organization with 28 member countries. I would suspect that any statements as sensitive as these would require consent from their membership." I do not think this is true. It would be frankly stupid to work like that. Anyone who wants to draw a benefit from science must leave free hands to the bona-fide researcher. Otherwise the whole project boils down to finding support for the innate, incomparable wisdom of some political leader (or a company director in the private sphere). Hunches and opinions are not a basis for rational decisions. However, I have to admit that many (if not most) actions are committed to on an emotional basis. A search for facts (cherry picking) comes later to justify the decisions. Man is not a very rational being. (The IPCC process that results in the "Summary for decisionmakers" is an anomaly. It is an effort to deliver something actionable. However, I have to trust that also the Government representatives in that negotiation know their science, but they also know politics - the art of possible.)
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Aug 27, 2012