Wednesday, March 19, 2008

Global Warming on Hiatus?

Could this be a sign that maybe we don't really understand the phenomenon of Global Warming? Or maybe the whole thing isn't as bad as we originally though:
Some 3,000 scientific robots that are plying the ocean have sent home a puzzling message. These diving instruments suggest that the oceans have not warmed up at all over the past four or five years. That could mean global warming has taken a breather. Or it could mean scientists aren't quite understanding what their robots are telling them.

This is puzzling in part because here on the surface of the Earth, the years since 2003 have been some of the hottest on record. But Josh Willis at NASA's Jet Propulsion Laboratory says the oceans are what really matter when it comes to global warming.

In fact, 80 percent to 90 percent of global warming involves heating up ocean waters. They hold much more heat than the atmosphere can. So Willis has been studying the ocean with a fleet of robotic instruments called the Argo system. The buoys can dive 3,000 feet down and measure ocean temperature. Since the system was fully deployed in 2003, it has recorded no warming of the global oceans.

Don't hold your breath, however. Heat has been flowing from the water to the air (aka El Nino). This phenomenon can be the reason why global air temperatures have risen while global sea temperatures have actually dropped by a small degree. The rise in global air temperatures have caused an increase in sea levels, due to the increase in the melting of Antarctic glaciers.

However, the increase in sea level cannot be accounted for with only glacial melting.

"But in fact there's a little bit of a mystery. We can't account for all of the sea level increase we've seen over the last three or four years," he says.

One possibility is that the sea has, in fact, warmed and expanded — and scientists are somehow misinterpreting the data from the diving buoys.

But if the aquatic robots are actually telling the right story, that raises a new question: Where is the extra heat all going?

Time will tell.

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