Chris, I also think your blog is excellent, and hope that you keep posting new things on your blog.

Here are some data from the spreadsheet I used yesterday night (perhaps of interest for double-checking the results, hopefully I calculated correctly).

x-variable: June PIOMAS volume for Arctic Ocean, excluding Hudson, Baffin, Bering, Okhotsk.

y-variable: September NSIDC sea ice extent

Regression equation (using the 1979-2013 period): y = 0.2808 * x + 0.1355

Predicted y-value for September 2014: y = **4.70**.

Extent is expressed in million km^{2}, volume in 1000 km^{3}.

`year, x, y, predicted y (hindcast), residual`

1979, 27.833, 7.20, 7.95, -0.75

1980, 27.301, 7.85, 7.80, 0.05

......

2007, 17.797, 4.30, 5.13, -0.83

2008, 18.964, 4.73, 5.46, -0.73

2009, 18.180, 5.39, 5.24, 0.15

2010, 16.215, 4.93, 4.69, 0.24

2011, 15.293, 4.63, 4.43, 0.20

2012, 14.902, 3.63, 4.32, -0.69

2013, 16.003, 5.35, 4.63, 0.72

2014, 16.265, ? , 4.70

Taking the minimal and maximal residuals of the 2007-2012 period, and adding them to the above y-value 4.70, gives the lower and upper bounds: [3.87,4.94]. Mid-range: y = **4.41**.