In 2004, NASA scientists started looking forward to a new solar minimum. In 2005, it began. At this time most scientists expected the new solar cycle 24 to begin in late 2006 or early 2007 with a following ramp up in solar activity.

But 2006 and 2007, according to NASA data, passed without any sign of a new solar cycle. During this time, the sun remained unusually quiet. Then, in early 2008, scientists finally found what they were waiting for -- a single sunspot with a reversed magnetic polarity. As a switch in magnetic polarity usually presages an increase in sunspot activity building up to a new solar maximum, scientists around the world proclaimed the new solar cycle had finally begun.

Now, nearly two months later, NASA observations show the sun is still unusually quiet. Day after day, the sun displays few, if any, sunspots. Even coronal holes are curiously absent. The long solar minimum now stretching into its third year coupled with curiously low solar activity even for a solar minimum is causing some scientists to speculate if the sun is entering a period of anemic activity like the most recent Dalton Minimum.

According to Wikipedia, the Dalton Minimum was a period of low solar activity stretching from 1790 to 1830. Like other long period solar minimums such as the Maunder Minimum and the Sporer Minimum, it resulted in crop failures, lower than average global temperatures, and little ice age conditions in the Northern Hemisphere.

If the sun is entering a new period of very low activity it would presage a 30 year or more drop in global temperatures. Some scientists are already beginning to speculate that just this sort of thing may be occurring now. According to Astronomer David Whitehouse, "It's something we must take seriously because what happened in the 17th century is bound to happen again some time. Recent work studying the periods when our Sun loses its sunspots, along with data on other Sun-like stars that may be behaving in the same way, suggests that our Sun may spend between 10 and 25 per cent of the time in this state. Perhaps the lateness of cycle 24 might even be the start of another Little Ice Age."

Usually, the first signs that the sun is emerging from its period of latent activity is the appearance of a series of small sunspots in the high latitudes. Whitehouse notes that these reverse polarity sunspots usually occur 12-20 months before the start of a new solar cycle. With only one high altitude sunspot discovered so far, what does this indicate about the sun's current state? According to Whitehouse, "the longer we have to wait for cycle 24 the weaker it will be. Such behavior is usually followed by cooler temperatures on Earth."