Why is this Artic meltdown so important?
Three words: "postitive feedback loops."
All the "scary math" up until now has ignored this one very fundamental thing that could make things much, much worse than even the worst case estimates in the IPCC reports until now. The possibility of positive feedback loops accellerating climate change was explicitly excluded from the IPCC reports because they are poorly understood and introduce potentially wildly chaotic responses. They actually say litterally: we're ignoring this because we don't understand it.
The rapid Arctic meltdown has proven that at least some positive feedback loops are already operating, that for this part of the global system the curve is exponential, not linear.
Now the very real and very great danger is the Arctic meltdown will or already has triggered other, even more significant positive feedback loops. Such as releasing the vast stores of Methane in sub-sea hydrates and the permafrost. If that turns out to be the case, then fasten your seatbelts... we're on the fasttrack to global meltdown already.
Take a look at this site: http://www.ameg.me/