The Arctic sea ice extent for 2015 has now dropped below the minimum extent of 1980 and continues to drop. Take a look at this plot from the National Snow and Ice Data Center:
With about eight weeks remaining, this year's extent is going badly. Take a look at these graphics from the Danish website, Polar Portal:
This shows the surface temperature of the ice. The dark line represents the extent of the ice. As you can see, the ice everywhere is above freezing. This is normal (it is summer up there, too), but indicates the ice is melting from above. It is melting from below from warm ocean water at the same time. The combination gives you this:
This shows both the extent of the ice and the percentage of ice coverage in a given area. The darker the shading, the more open water there is and less ice. Compare this to last year at this same time:
There's a big difference. This year is quite a bit worse than last year. But, there is more than just extent. After all, 20% coverage is the same as 100% when you talk about extent. What about ice thickness?
The more purple the color, the thinner the ice. As
you can see, there are vast areas on the verge of completely breaking
apart.
And ice volume:
This graph shows the total volume of ice. 2015 is tracking to be the second-lowest volume ever recorded.
This is how these two values looked at the same time last year:
Based on this data, I believe we will see one of the worst sea ice minimum extents ever measured. There are still almost two months to go before we see the minimum, but this year's extent is already less than the minimum extent of 35 years ago and declining rapidly. I expect to see the extent fall somewhere around the 2007 or 2011 minimum, which would make this year in the range of being the second-worst extent ever measured. That would be consistent with the trend line:
Future postings on this subject will follow as we approach the minimum in late-September.
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