Shifting ocean currents can (and do) actually speed up Earth's rotationS

Time just flies by, and that was especially true during the first half of November 2009, when the Earth's daily spin around its axis became 0.1 milliseconds shorter. You can blame that lost time on the waters around Antarctica.

Back in November 2009, something strange happened the Southern Ocean. The Antarctic Circumpolar Current suddenly slowed down. The change in current was extreme enough to throw off the planet's angular momentum, and so to compensate, the Earth sped up its rotation. For about two weeks, the days were a tenth of a millisecond shorter than they should be. Then, with just as little warning, the current returned to its normal speed, and the Earth slowed back down.

Such rotation-altering phenomena aren't unknown, but they usually take the form of changing wind formations instead of ocean currents. It's also unprecedented to see such a large change from the oceans throw off the Earth's rotation so quickly, according to Stephen Marcus and fellow researchers at NASA's Jet Propulsion Laboratory.

The big question is why this happened - as New Scientist reports, it's possible that the root of all this may be El Niño. The unusual climate pattern could have thrown off wind speeds around Antarctica, which in turn would have driven the current to slow down. That points to a possible link between climate change, which has made El Niño occur more frequently, and these shifts in Earth's rotation.

While this sort of temporary, tiny rotation change isn't that big a deal as these things go, some of the other side effects of alterations to the Antarctic Circumpolar Orbit are more of a concern. The frozen continent's ice sheets and glaciers are linked to the currents, and an unexpected, sudden change in one could impact the other. And, of course, there's still the little matter of those lost 1.5 milliseconds worth of productivity back in November 2009. Well, at least I now know why I never finished my novel...

For more, check out New Scientist. Original paper at Geophysical Research Letters. Image via NASA.