The infamous “hockey stick” graph, which shows the northern hemisphere beginning to rapidly warm around the industrial age, has been backed up by new research. Michael Mann, who helped develop the 1998 graph that climate skeptics love to hate, is the lead author of the new study to be published in the Proceedings of the National Academy of Sciences. “Ten years ago the estimates for earlier centuries were really primarily reliant on just one sort of information: tree ring measurements,” he says. For the new study, researchers perused coral reef skeletons, glaciers, ice sheets, sea-floor sediment, stalagmites, and stalactites. Thus, says Mann, “we now have enough other sources that we can achieve meaningful reconstructions back a thousand years without tree ring data, and we get more or less the same answer” — that is, that “the current warmth is anomalous.”
