15 December 2007

New Sunspot Cycle 24 Trying to Start: Is a Cooler Sun the Answer to Global Warm Mongering?

In Bali, global warm-mongers are packing their tents--most of them to return to the freezing cold of a northern hemisphere winter. Meanwhile, in the real universe on the surface of Sol, fascinating forces are at work.
The solar physics community is abuzz this week. No, there haven't been any great eruptions or solar storms. The source of the excitement is a modest knot of magnetism that popped over the sun's eastern limb on Dec. 11th, pictured below in a pair of images from the orbiting Solar and Heliospheric Observatory (SOHO).

It may not look like much, but "this patch of magnetism could be a sign of the next solar cycle," says solar physicist David Hathaway of the Marshall Space Flight Center. For more than a year, the sun has been experiencing a lull in activity, marking the end of Solar Cycle 23, which peaked with many furious storms in 2000--2003. "Solar minimum is upon us," he says.

The big question now is, when will the next solar cycle begin?

"New solar cycles always begin with a high-latitude, reversed polarity sunspot," explains Hathaway. "Reversed polarity " means a sunspot with opposite magnetic polarity compared to sunspots from the previous solar cycle. "High-latitude" refers to the sun's grid of latitude and longitude. Old cycle spots congregate near the sun's equator. New cycle spots appear higher, around 25 or 30 degrees latitude.

As most Al Fin readers know, there is good reason to suspect a link between global cooling and solar cycles. The Little Ice Age of the 1500s through the 1700s may have been triggered by a solar cycle similar to the one due to occur in the late 20-teens. Several solar scientists have predicted significant cooling beginning in the 20-teens and lasting for between 30 and 50 years.
Though Hathaway is among some solar physicists who believe cycle 24 will be very active (though 25 very quiet), the majority believe it will continue the decline started in cycle 23 which peaked 25% lower than the two previous cycles and forecasts. See a compilations of forecasts here. Also note cycle 23 would have lasted 11 years 7 plus months, more than a full two years longer than cycle 22. Longer cycles usually lead to colder temperatures. Leif Svalgaard notes it was at rather low latitude (for a new cycle spot). This is usually a sign of a weak cycle. The stronger the cycle the higher the latitude of the first spots.

We are in for some interesting climate cycles, courtesy of our friendly local star, Sol.

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