I'm writing this post as a complement for the 2017 Sea Ice Thread.
As rjh01
was commenting there, there's not only the issue of lesser sea ice area and extent but its thickness is also a concern. We know it is thinning year after year, even in high latitudes.
But this looks like a static process, and it surely isn't. What is more worrying is that thinner ice fosters the creation of new ice, as ice is a formidable insulator. But that isn't happening, and the key is this graphic:
[qimg]http://i65.tinypic.com/160vko0.png[/qimg]
Take a look (red plot) to the real surface temperatures above 80°N the first 60 days of last year, and so far this year (I appended this year's figure to the right of last year's). Look how they are some 7°C (13°F) above the mean values for the 1958-2000 period.
If you give it a thought you'll discover the cause by yourself. Think that happens during the polar night so no incoming energy from the sun, only outgoing energy. But the temperatures don't drop, where is all the lost heat coming from? Some 20-25% comes from new ice that is created as it renders the same heat that it will reabsorb during the melting season. The rest comes from lower latitudes, because the polar regions get most of their energy from lower latitudes. Only during a 4 or 5 weeks around the solstice they get as much energy from the Sun as they radiate into space.
Do those +7°C come from more heat originated in lower latitudes reaching the polar regions? Yes,
some of them. But remember that the higher the temperatures, the easier for the atmosphere to radiate that heat back into space. Then, what's hidden there? Haven't you figured it out yet? The last clue: I took those graphics from a webpage belonging to the Ocean and Ice Service of the Danish Meteorological Institute. If you
go there you can browse year by year and get a more complete picture. Look how temperatures during January and February were rising slowly year after year until this century. Even 1997 and 1998, the year "the pause" supposedly started, temperatures were about normal. But from then on it's all going from bad to worse.
Don't you get it yet? Well, stop please, I'll tell: GHG in all their glory. The surface of the ice radiates different frequencies according to its temperature, and some of them are blocked by GHG more efficiently than others. As the sea ice cover dwindles and more heat comes from lower latitudes the Arctic warms and becomes more humid, and that causes more warming because of an enhanced GHG effect from the atmosphere over the region.