What is Normal?

It seems that 29 years of satellite observation may in fact not be enough to fully understand climate cycles that can last tens, hundreds, or thousands of years:

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 trend…

"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….

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.

Yes, the Artic is a degree or two warmer (it has for various reasons, understood and not yet understood) experienced the most warming worldwide.  In contrast, the southern hemisphere, and particularly the Antarctic, have not really warmed at all, and have seen all time highs in ice.

HT to Bruce Hall.  For this reason and many more, I titled my climate video "What is Normal?"  By the way, the video is over 2000 views on Google video and YouTube, and over 600 people have downloaded the movie.

  • “The Arctic Oscillation was fairly stable until about 1970…”

    How do we know this?
    And, if it’s true, why would it become less stable after 1970?