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George R.R. Martin’s wildly popular Game of Thrones saga—whose third season just launched on HBO—is, on the broadest level, a story driven by climatic change. “Winter is coming,” warn the ill-fated Starks, a family of northern nobles who help guard the realm from the frozen beyond. In Martin’s world, winters and summers vary in length and can for last years or even a generation—and as the books advance, a devastating winter begins to descend, forcing southward migrations and an intense test of mettle to see who can literally stand against the cold.
Back on Planet Earth, our own weather has felt distinctly Game of Thrones-like lately—depending heavily, of course, upon where you live. But if you’re in the northeastern U.S., 2012 felt like a long summer, with scarce any winter at all—whereas early 2013 featured a snowy winter that has felt like it won’t end (though it finally does now seem to be letting up). See here for a graphic of March temperature anomalies in 2012 and 2013, courtesy of Climate Central, proving this perception isn’t merely subjective:
The UK—a kind of homeland for Game of Thrones, in that the books are inspired by England’s historic “Wars of the Roses,” and the gigantic ice wall in the north of the fictional Westeros is modeled on Hadrian’s Wall, built by the Roman emperor to protect against tribes of Britons—is also undergoing a staggering winter this year. A recent Daily Mail report features disturbing pictures and video of sheep frozen to death in giant snow drifts, noting that the current freeze is threatening to persist throughout April.
So what’s going on here? Could climate change actually give us a Game of Thrones world with longer, or at least more variable, winters and summers? On an admittedly much more modest scale—we’re working with mere physics here, not a recurring meteorological conflagration between good (heat) and evil (cold)–the answer may be yes.
One key factor behind the UK’s and East Coast’s supercharged winter of 2013 is the odd behavior of the jet stream, the high level river of air that meanders from west to east in the mid-latitudes of the northern hemisphere. Jennifer Francis, a climate scientist at Rutgers University, explains that climate change is weakening the jet stream through an unexpected mechanism—the dramatic melting of ice in the Arctic. And this, in turn, is leading to more fixed weather patterns—whether hot or, alternatively, intensely cold—across the globe.