Solar activity, which usually runs in 11-year cycles, has been so sluggish of late that space weathermen are worried we might be entering a mini-ice age. They expected to see sunspot activity pick up about last March, to peak in 2012; if the sun stays this sluggish for another year or two, it could trigger a prolonged period of massive snowfall and severe cold across the Northern Hemisphere, Popular Mechanics reports.
The last solar lull occurred about 350 years ago, resulting in 65 years of winters so fierce that people walked from Manhattan to Staten Island over a frozen New York Harbor. But the sun's magnetic fields are only part of the puzzle; other factors, including volcanic activity and the Black Death reducing the rate of European tree-cutting, may have also played a role. In fact, one study says that solar effects on climate are dwarfed by the results of man-made greenhouse gases.