One of my biggest gripes about the global warmingistas is that they have never attempted an vetted, provable, reproducible and justifiable study of temperature change over a long period of time. Professor Jan Esper undertook a painstaking review of tree ring data from fossilized trees in the Finish Laplands dating back to 138 BC. Sure enough, he found measurable climate change over time. Yup, that right. The earth has been steadily cooling since the Roman and Medieval times.