January 29, 2014

More polar vortex talk

Last night, in honor of the bone-chilling temperatures afflicting the US, I watched "The Day After Tomorrow". What can I say? Watching a movie about the world experiencing a new Ice Age just seemed appropriate. We're not exactly freezing in place within 15 seconds, like in the movie. But we're experiencing temperatures that are lower than any I remember in NY history.

At one point in the movie, I heard Dennis Quaid's character say that climate change was shutting down the North Atlantic Gyre, the ocean current that brings warmth up from the tropics. And this is what was causing a new Ice Age.

In recent years, I wondered when and how this idea wormed its way into the American consciousness. It's kind of funny that the source is a Hollywood movie. Turns out, a new Ice Age is not on the way -- at least, on the real Earth that we occupy. And how do I know this? Because NASA told me so.
Predictably, talk of such a scenario has led to some big misconceptions. First, a slowdown or even a stoppage of the meridional overturning circulation would NOT spell the end to the Gulf Stream. Wind and large-scale turbulence drive the bulk of the Atlantic Subtropical Gyre, of which the Gulf Stream is a part. The Gulf Stream would, however, draw significantly less water from the tropics.

Second, unlike during the Younger Dryas, a weakening of the meridional overturning circulation will NOT trigger another ice age. Rising temperatures due to global warming would offset most of the temperature drop. Armadas of icebergs floating off the New Jersey coast are just Hollywood fantasies.
So there you go. No Ice Age. I'm still not thrilled about the Gyre slowing down and possibly stopping. But at least it won't look like the world depicted in "The Day After Tomorrow". Thought I'd share this news with y'all.

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