Grinnell Glacier at Glacier National Park
Source: Wikimedia Commons

A team of Arctic geochemists recently robbed climate change skeptics of one of their most beloved seeds of doubt—historical ambiguity. Without thousands of years of temperature data, questioners have claimed, how can we know that the Arctic’s recent spate of steamy summers is really a manmade anomaly, and not just a natural hiccup in the region’s climate?

The geochemists’ new study, published in September in the journal Science, provides such data. Through analysis of glacial ice cores, tree rings and Arctic lake sediments, the study’s authors were able to expand the previous 400-year temperature history of the region by an additional 1,600 years. The result is a two millennia-long narrative of the Arctic’s climate that unfurls decade by decade. What surprised scientists in sifting through this new data was the discovery that 2,000 years ago, Earth was in the grip of a cooling trend that seemed determined to plunge the planet into the next Ice Age.

The good news is that through our steadfast combustion of fossil fuels we appear to have thwarted our icy fate. The data show that just a handful of decades after the industrial revolution found its groove, Arctic temperatures stopped sinking and started rising.

The bad news is that since 1950, we’ve experienced five of the six hottest decades with the balmiest one to date ending just last year. “Climate change is itself nothing to be scared of,” says Mark Serreze, a senior research scientist at the National Snow and Ice Data Center. “The issue we’re facing today is the rapid rate of change, with the question now being: Can we adjust?”