We here at Plenty are fairly used to seeing strange happenings in New York City. Whether it’s raving weirdos on the subway or hoards of tourists in matching t-shirts, we’re rarely thrown for a loop. But when the temperature reaches into the 70s in January as we've heard it might tomorrow—now that freaks us out.

The high temperatures have a lot of people asking whether global warming is responsible for the heat wave. The best answer we’ve found came from an exceptionally well-done article in yesterday’s Christian Science Monitor.

Probably, says the article, a climate pattern called the North Atlantic Oscillation (NAO) is the most immediate cause of the balmy weather:

The phenomenon swings between two states. When the NAO is positive, a large region of high pressure appears over the central Atlantic, while a large area of low pressure settles over southern Greenland. Each of these features are stronger than usual, leading to more-severe Atlantic storms that travel on a more northerly track than usual. This leads to wet, mild winters in the Eastern U.S. and northern Europe. When the NAO goes negative, the high and low pressure areas weaken and shift south. Storms are weaker and travel more directly west to east.

The NAO can have wide-ranging ecological effects—from changes to the location, frequency, and intensity of storms and wildfires to shifts in crop and fisheries yields. And it can have a profound effect on energy demand. Energy analysts note that crude oil and natural gas prices have eased, partly because of the mild winter so far.

The next question to ask is whether global warming is exacerbating the NAO—and that’s where scientists are less sure. Part of the problem is that unlike other well-known climate patterns (like El Niño), NAO is hard to predict and track. So NAO is something of a mystery—for now. What’s not a mystery, though, are all the sales we’re seeing on heavy sweaters and winter coats.

Posted by Kiera Butler on Jan 5, 2007 at 9:00 AM
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