11,000 Years of Climate History

marcott-B-CDIn the most ambitious study yet attempted of its kind, Shaun Marcott et al. have just published in Science their findings that the current bout of climate change is happening at a rate unprecedented in the last 11,300 years.

Previous climate reconstructions, like Michael Mann’s (in)famous hockey stick (PDF), had examined trends primarily over the past 2,000 years, so Marcott and his team dramatically expanded current knowledge of global climate trends. In their paper, they largely corroborate several important points of consensus in the existing literature. First, while the current temperature is not yet the highest over the 11,300 years studied (that honor goes to the interglacial period), our rate of temperature rise far outpaces anything previously experienced. Secondly, the climate was undergoing a period of cooling starting about 5,000 years ago that ended about 100-200 years ago. In fact, Marcott noted in an interview with the New York Times that “we were on this downward slope, presumably going back toward another ice age.”

This comprehensive data is the most damning evidence yet that anthropogenic emissions are causing climate forcing at a scale unknown in world history.

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