This is the kind of analysis one can do with the interactive graph linked to above

![val](http://imageshack.com/a/img537/3528/M6XySw.png)

The training interval is set from 1930 to 1980 and the validation interval is 1880 to 1930

This is a very aggressive set of parameters but the truth is in there somewhere.

I can imagine integrating this with the [CSALT model of AGW](http://contextearth.com/2013/10/26/csalt-model/) I developed a couple of years ago.