2012: Hottest Year Ever for the US, Arctic Sea-ice at Record Low

Some effects of sea-ice loss in the Arctic:

Heating of the arctic ocean and contiguous land masses:
-Release of methane and CO2 from permafrost areas
- Increased melt of the Greenland ice-cap. In terms of sea-level rise, this is the big one- the Greenland ice-cap, in some places 3 kilometers thick, is melting rapidly. If all that ice melts and drops into the ocean, sea-levels will rise by 7 meters.
- Reduced salinity in the North Atlantic is weakening  the Atlantic conveyor circulation at the northern end, destabilizing climate in Northern Europe
- Open seas in the arctic have oil and gas exploiters planning major drilling and extraction, the burning of this additional carbon will itself  increase atmospheric CO2 and global heating

-Reduced heat differential between Arctic and mid-latitudes: reduced strength of jet stream;
    - which allows arctic air to pour down into mid-latitudes and remain there for a longer time (extreme winter cold snaps, US and Europe 2010, 2011)
    - and allows very warm air to pour into arctic areas and remain for longer (2012 flash melt of greenland ice surface)

Update, Oct 26. One of those above-mentioned arctic outpourings is underway, with our local daytime temperatures dropping 30 degrees in 2 days. This arctic blast will collide in a few days with Hurricane Sandy,  a huge storm moving up the coast toward New York City. Sandy  is  blocked from a normal northeasterly trajectory by a high pressure mass sitting over Greenland, and is expected to lurch westward directly into the most heavily populated area of North America; the resulting hybrid storm could produce severe damages and flooding. The penetration of the arctic air mass, the late season hurricane, and the high pressure mass stuck over Greenland are examples of weather effects expected to accompany climate change, and here they may hybridize and produce a real mess on the East Coast.
At the same time, the last debates of the presidential campaign of 2012 are over, and for the first time since 1988, the subject of climate change was not even broached. Instead both candidates competed in promising more drilling and oil production.