At the end of the day, interpolation is nothing more than an estimate which is incredibly unreliable when attempting to estimate something as chaotic and variable as a temperature and, even more so, over surfaces of tens of thousands of square kms where there are no measurements. I'm sure it's reliable in a lot of scenarios but can it be relied upon to fill in the gaps for an average global temp?
The temps in my backyard are almost always different to the temps in my front yard (for whatever reason - it doesn't matter). I have never been convinced that an accurate average global temp can be measured, particularly to 1/10th of a degree, and remain as skeptical as ever. Do you think using proxy data of 500 years ago and comparing it with actual readings of today is comparing apples with apples?
