and so we took all of the information that was available at the t time fromom records ofs sortrt, so-called proxy recocor, toto estimate how the temperatue of the earth, specifically the northern hemisphere where we had the most data, how the temperature of the northern hemisphere had changed over the past 1,000 years. and what we found was--although the estimates are uncertain, as yoyou can imagine bececause we'e not working with thermometers, we're working with these very imperfect natural thermometers like tree rings and ice cores. so there's this band of uncertainty. but even when you look at the band of the uncertainty back in time, you see that the recent warming is outside of f the range that e see over the past 1,000 years. there's no evidence that a warming of this magnitude happens nataturally, at least as far back as w we uld go. it led to a chart, which depicts temperatures starting out fairly warm 1,000 years ago, getting colder as you descend into the depths of the little ice age, and then, of course, the rapid warming of the past century, the spike at the end. it was the shap