Solar activity drops to 100-year low, puzzling scientists

Predictions that 2013 would see an upsurge in solar activity and geomagnetic storms disrupting power grids and communications systems have proved to be a false alarm. Instead, the current peak in the solar cycle is the weakest for a century. Subdued solar activity has prompted controversial comparisons with the Maunder Minimum, which occurred between 1645 and 1715, when a prolonged absence of sunspots and other indicators of solar activity coincided with the coldest period in the last millennium. The comparisons have sparked a furious exchange of views between observers who believe the planet could be on the brink of another period of cooling, and scientists who insist there is no evidence that temperatures are about to fall. New Scientist magazine blasted those who predicted a mini ice age, opening a recent article on the surprising lack of sunspots this year with the bold declaration: "Those hoping that the sun could save us from climate change look set for disappointment". "The recent lapse in solar activity is not the beginning of a decades-long absence of sunspots, a dip that might have cooled the climate. Instead it represents a shorter, less pronounced downturn that happens every century or so," ("Sun's quiet spell not the start of a mini ice age" July 12). The unusually low number of sunspots in recent years "is not an indication that we are going into a Maunder Minimum" according to Giuliana DeToma, a solar scientist at the High Altitude Observatory in Colorado. But DeToma admitted "we will do not know how or why the Maunder Minimum started, so we cannot predict the next one." Many solar experts think the downturn is linked a different phenomenon, the Gleissberg cycle, which predicts a period of weaker solar activity every century or so. If that turns out to be true, the sun could remain unusually quiet through the middle of the 2020s. But since the scientists still do not understand why the Gleissberg cycle takes place, the evidence is inconclusive. The bottom line is that the sun has gone unusually quiet and no one really knows why or how it will last...more