‘Hibernating’ sun could spark Little Ice Age
Man-made global warming might be offset by cooling effect of disappearing sunspots
The sun's 11-year sunspot cycle could be heading for a dormant period similar to one which caused the so-called Little Ice Age of the 17th century, when markets were held on a frozen River Thames in London.
Three scientific studies offer evidence that sunspots are on the verge of disappearing. Frank Hill, associate director of the National Solar Observatory (NSO), said yesterday: "This is highly unusual and unexpected, but the fact that three completely different views of the sun point in the same direction is a powerful indicator that the sunspot cycle may be going into hibernation."
The current solar cycle, named Cycle 24 by scientists, is entering its period of maximum activity, and will climax in 2013. The processes that lead to a period of maximum activity during the next 11-year oscillation, Cycle 25, should by now be evident. However, the Christian Science Monitor reports, a study of the sun's acoustic signals led by Hill has found no such evidence.
Another study, by Matt Penn and William Livingston of the NSO, has found that the sun's magnetic field strength has fallen over the past 13 years. If the trend continues, says Penn, there may be no sunspots during Cycle 25.
The third study was led by Richard Altrock, who heads the US Air Force's corona research program. They studied 40 years' worth of data and predicted that the Cycle 24 solar maximum due in 2013 may not happen at all.
Hill says that if the three studies are correct, the next solar maximum could be the last we will see for a few decades. Reduced sunspot activity raises the possibility of a second 'Maunder Minimum' - a period from 1645 to 1715 during which virtually no sunspots were observed. These decades were marked by extremely cold winters in Europe and North America and are known as the Little Ice Age.
Of course, as any statistician will tell you, correlation does not imply causation.
But it is impossible not to speculate how a possible cooling of the earth will be affected by man-made climate change. Tom Woods, associate director of the Laboratory for Atmospheric and Space Physics at the University of Colorado, told the Arizona Daily Star he thinks any fall in temperatures caused by a dormant sun will be disguised by global warming.
Hill himself is hedging his bets, saying: "I have not seen enough evidence either way to say whether solar activity is responsible for climate effects or not... if the next solar cycle, Cycle 25, does not occur, we'll have a splendid opportunity to find out." ·
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