A NASA press release yesterday reveals that university researchers and a team from NASA have detected an ongoing reversal in Arctic Ocean circulation that may be responsible for many of the changes in the Arctic currently being blamed on global warming. The reversal in ocean circulation is triggered by atmospheric circulation changes that vary on decade-long time scales.
"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 James Morison of the University of Washington's Polar Science Center Applied Physics Laboratory, Seattle. "While some 1990s climate trends, such as declines in Arctic sea ice extent, have continued, these results suggest at least for the 'wet' part of the Arctic -- the Arctic Ocean -- circulation reverted to conditions like those prevalent before the 1990s," he added.
The Arctic Oscillation was fairly stable until about 1970, but then varied on more or less decadal time scales, with signs of an underlying upward trend, until the late 1990s, when it again stabilized. During its strong counterclockwise phase in the 1990s, the Arctic environment changed markedly, with the upper Arctic Ocean undergoing major changes that persisted into this century. Many scientists viewed the changes as evidence of an ongoing climate shift, raising concerns about the effects of global warming on the Arctic.
Morison said data gathered by Grace and the bottom pressure gauges since publication of the paper earlier this year highlight how short-lived the ocean circulation changes can be. The newer data indicate the bottom pressure has increased back toward its 2002 level. "The winter of 2006-2007 was another high Arctic Oscillation year and summer sea ice extent reached a new minimum," he said. "It is too early to say, but it looks as though the Arctic Ocean is ready to start swinging back to the counterclockwise circulation pattern of the 1990s again."
Of course, the news being particularly damaging to the global warming propaganda machine, it comes with the warning that some computer models indicate that global warming might make these natural Arctic Oscillations stronger in the future.