Tuesday, November 27, 2007

Arctic Ocean circulation reverses, again

It used to be one way, then it changed, then it changed again, and you know, it might change again! What a wild idea.

Arctic Ocean Circulation Does An About-Face

ScienceDaily (Nov. 14, 2007) — A team of NASA and university scientists has detected an ongoing reversal in Arctic Ocean circulation triggered by atmospheric circulation changes that vary on decade-long time scales. The results suggest not all the large changes seen in Arctic climate in recent years are a result of long-term trends associated with global warming.

The team, led by James Morison of the University of Washington's Polar Science Center Applied Physics Laboratory, Seattle, used data from an Earth-observing satellite and from deep-sea pressure gauges to monitor Arctic Ocean circulation from 2002 to 2006. They measured changes in the weight of columns of Arctic Ocean water, from the surface to the ocean bottom. That weight is influenced by factors such as the height of the ocean's surface, and its salinity. A saltier ocean is heavier and circulates differently than one with less salt.

The very precise deep-sea gauges were developed with help from the National Oceanic and Atmospheric Administration; the satellite is NASA's Gravity Recovery and Climate Experiment (Grace). The team of scientists found a 10-millibar decrease in water pressure at the bottom of the ocean at the North Pole between 2002 and 2006, equal to removing the weight of 10 centimeters (four inches) of water from the ocean. The distribution and size of the decrease suggest that Arctic Ocean circulation changed from the counterclockwise pattern it exhibited in the 1990s to the clockwise pattern that was dominant prior to 1990.

Reporting in Geophysical Research Letters, the authors attribute the reversal to a weakened Arctic Oscillation, a major atmospheric circulation pattern in the northern hemisphere. The weakening reduced the salinity of the upper ocean near the North Pole, decreasing its weight and changing its circulation.

"Our study confirms many changes seen in upper Arctic Ocean circulation in the 1990s were mostly decadal in nature, rather than trends caused by global warming," said Morison.
Thanks to Bill Quick at Daily Pundit. The GRACE satellites were previously mentioned here in Canada still affected by the last ice age.

2 comments:

theobromophile said...

The magnetism of the earth changes, too. :)

One only need to look at planets unaffected by human life (or any life at all) to see that there are massive changes which occur, independently of our activities.

Hector Owen said...

My second post here was Oh no, not Pluto! And then you have the Martian polar icecaps melting, and so on.

I'm torn between thinking that the AGW hysteria is just hubris, and that it's [conspiracy alert!] part of a plan for the creation of a world government, which would of course be run by the people who would be the last ones you would want to see doing that. But it could be both of those things at the same time. The AlGorean gospel, as far as I can make it out, is that the climate we had when he was a boy is the perfect climate, and so the whole world must be constrained to keep everything exactly the way it was then. And if he can make a few million $ in the course of all that, well, that's just doing well by doing good.