[Old Professer]

Haven’t found the paper or the abstract.

How do they do this usingfive data points?

[cogitator]

From Prof. Gillett's Web site (amazing what the right keywords can do in Google, I used - Stott Gillett Antarctica and "Nature Geoscience"):

http://www.cru.uea.ac.uk/~nathan/pdf/ngeo338.pdf

Have fun: gotta go trick-or-treating. I'm going dressed as a CO2 molecule and I'm going to hit a lot of the houses of liberals I know: that should scare them!