...could it be that Greenland is indeed dropping much more - possibly, times more, - meltwater every year in compare to what it was just some 3+ years ago?
If this were happening I would expect it to have been picked up by the GRACE satellites.
These are using gravity measurements to measure the melt/snowfall accumulation of the Greenland and Antarctic Ice Sheets. If you visit the blog of Jason Box - http://www.meltfactor.org/blog/?p=1120 - you find that the Grace estimate for 2012 was a contribution of just under 1.5mm from Greenland melt to global sea level. The up to date graphs are here: http://polarportal.dk/en/greenland-ice-shelf/nbsp/total-mass-change/
As to the SSTs to the West of Greenland, I can find a map of the sea level depths here - http://geology.com/world/arctic-ocean-bathymetry-map.jpg - which shows that the seas there are relatively shallow. I think the warm SSTs there are just a result of early sea-ice melt allowing the shallow seas to warm in the sunshine, just as in the Barentsz sea.
Anomalously warm SSTs there (near both east and west shores of Greenland, 72-73 degrees northern latitude) are certainly influenced by sunshine, no doubt; however, can't be solely caused by it for a simple reason: the very map you are showing demonstrates shallow shelves along those coasts being all the way from 64 degrees up to 83 degrees northern latitude. If sunshine would be the sole or main driver, then we'd see a gradient of steadily dropping from south to north temperatures. Instead, we see 2 definite anomalous regions with high SSTs, with SSTs being a few degrees lower both to the south and to the north.
GRACE data for 2012 and 2013 - up-to-date graph your gave a link to, - is very interesting. It does show that during summer times (July, August - exactly the time we are at now) Greenland loses ~150...170 cubic kilometers of mass, net change per month. So, it's 150+ billions of tons of meltwater a month = ~5 billions tons of meltwater dropped into Arctic ocean every day.
If we'd imagine that ~4 billions tons of that comes out as two big "rivers", one flowing to the east and the other to the west, each dropping some ~2 billions tons of water every day, then that's exactly what could be causing those anomalously high SSTs along Greenland coast at ~72...73 degrees.
Ob - one of largest siberian rivers, - has average discharge of 12.475 cubic meters per second. Roughly, 12.500 tons per second = 1,08 billions tons every day.
There is a link from the graph you gave to this abstract:
http://www.the-cryosphere-discuss.net/6/3397/2012/tcd-6-3397-2012.html . Which says (quote, part):
"... For the whole GRACE period our trend estimate for Greenland is −234 ± 20 Gt yr−1 ... These trends show a clear (with respect to our errors) increase of mass loss in the last four years. " Clear it indeed is, seeing 2012 is some 500+ Gt yr-1 mass loss.
So the authors themselves admit that last few years, there was large ("clear with respect to our errors") increase of annual mass loss. But then, why they INCLUDE years 2011 and 2012 into the "average" - into the base with which recent years are to be compared to? Why on both graphs i see on the page you gave the link to -
http://polarportal.dk/en/greenland-ice-shelf/nbsp/total-mass-change/ - these last years with greatly increased mass loss are included into the average? You see, including last 2 years - with the dataset being only a decade, - increases the average dramatically, makes it closer to 2012 values. 95% confidence area also moves up much. This creates an impression of slower than actual increase of meltwater discharge. No idea if they did this intentionally or it was just sloppy thinking on their part; anyhows, in the abstract itself, they give that simple number - ~234Gt net mass loss per annum for Greenland, - and on their graph for 2012, we can see it was more than 500Gt net mass loss for 2012. So it more than DOUBLED in reality, - something not readily obvious from graphs themselves exactly for the reason i just described.
Thank you for links and your opinion, but so far i still think it's meltwater which creates those two large SST anomalies along Greenland costs. I still think increase in annual meltwater discharge from Greenland affects polar region noticeably, and if amount of meltwater discharge would continue to grow, so will continue to grow this process' significance for (remnants of) Arctic sea ice, ocean itself, and climate in Arctic.
edit/addition: I made a picture to illustrate the idea which i meant earlier:
where:
1 - Arctic ocean;
2 - Greenland's ice sheet (part);
3 - Greenland's rockbed;
L1 - under-ice lake #1;
L2 - under-ice lake #2.
years given are just to illustrate time flow, otherwise meaningless: no intention to define time scale of the process nor any actual dates of any tipping points.
So you see, as time go on and amount of melt water which sips down to those lakes from above increases bit by bit, lakes get bigger - they "eat" the ice which is their "ceiling", - and at some point, becoming "full" with liquid water in terms of rockbed, excess water from them start to run out - eventually to Arctic ocean.
Depending on rockbed profile, increases may happen
- gradually, as is the case on this picture: "lower" and "smaller" lakes get full 1st and whatever water was previously just adding to their volume - starts to run out to the ocean, however, "larger" and/or "higher" lakes are not full yet, and don't yet start to produce excess runout (the middle part of the picture above, marked "2012", is such a state); but once thos bigger and/or higher-placed lakes get full, they further increase net meltwater runout ("2015" case in the picture).
- abruptly, - which would be the case if L2 on the picture would get "full" before L1 would. Then, at some point, excessive meltwater runout from both lakes would "instantly" start to go into Arctic ocean - since before that instant, all excess water from both lakes would still end up filling either L1+L2 or still L1 alone.
Real rockbed is, of course, varied; some places, it's gradual increase from this, other places it's abrupt. Net total is, therefore, would be somewhat gradual increase of annual meltwater runoff from Greenland, but will some spikes of increase, spikes of all possible sizes, but the larger the spike, the less often it happens.
No idea if this would be useful to anyone, but here it is, i have this thought, i shared it before i'd forget it.
