Originally Posted by gerv

Could you tell us a little more? Give us some data...

From what I read, most of this type of data comes from information like tree ring growth and glacial ice cores. I don't know much about the latter, but I have looked at tree rings and you can see each ring is not the same. You can also count the rings back to years you know had bad weather and correlate the small rings with the lower temps.

But if you know otherwise, please let us know...