It would be difficult to overstate the significance of this development. We are now seeing changes occur in a matter of years that, in the normal geological scheme of things, should take thousands, even millions of times longer than that. On the basis of the 2012 melt season, one of the world’s leading experts on the Arctic ice cap, Peter Wadhams, of Cambridge University, has predictedthat the Arctic Ocean will be entirely ice-free in summer by 2016. Since open water absorbs sunlight, while ice tends to reflect it, this will accelerate global warming. Meanwhile, recent research suggests that the melting of the Arctic ice cap will have, and indeed is probably already having, a profound effect on the U.S. and Europe, making extreme weather events much more likely. As Jennifer Francis, a scientist at Rutgers, observed recently in a conference call with reporters, the loss of sea ice changes the dynamics of the entire system: “It’s like having a new energy source for the atmosphere.”

Yet, as big as the almost certainly irreversible retreat of the sea ice will figure in the future of the planet, it has attracted relatively little attention in the here and now. A study released on Thursday by Media Matters for America, a liberal watchdog group, found that over the last few months, Representative Paul Ryan’s fitness routine—he’s a big fan of what’s known as the P90X workout plan—has received three times as much television coverage as the ice loss.