A hindcast is a reverse forecast.

All data is "tainted" between 1880 and 2013 because that is what I have been using for a fit. So I need to go backwards from that point. The GISS data only starts at 1880, but the British HadCRUT temperature data goes back further.

![hind](http://contextearth.com/wp-content/comment-image/4848.gif)

It works to 1866, which is where the SOI data starts.

http://contextearth.com/2014/01/19/reverse-forecasting-via-the-csalt-model/


---


If it is OK to use the tainted range, one can test against training intervals within this range

http://contextearth.com/2014/01/22/projection-training-intervals-for-csalt-model/

This is a set of different training intervals that project after the up-arrow

- 1880-2000
- 1880-1990
- 1880-1980
- 1880-1970
- 1880-1960
- 1880-1950


![training](http://imagizer.imageshack.us/a/img801/3659/ipy.gif)