Elsewhere, The Resilient Earth notes the following:
A dramatic correlation between sunspots and global temperatures can be seen in historical records going back several centuries. During the Maunder Minimum, a period of diminished solar activity between 1645 and 1715, sunspots were rare on the face of the sun, sometimes disappearing entirely for months to years. This period coincides with the Little Ice Age, an historically famous time of abnormal low temperatures. It is certainly too early to claim that we are entering another pronounced solar minimum; to match those historical minima in depth and longevity, the current minimum will have to last considerably longer than it has so far.
As can be seen from the graph below, the correlation between sunspots and temperature is quite pronounced, with climate following sunspot activity much better than recent charts of fluctuating temperatures vs. steadily increasing CO2. Are the events connected? Scientists cannot say for sure, but it seems quite likely. Slowdowns in solar activity, as evidenced by reductions in sunspot numbers, are known to coincide with decreases in the amount of energy discharged by the sun.
On recent solar cycles, see this study from the National Oceanic and Atmospheric Administration (NOAA)in 2009.
"Even a below-average cycle is capable of producing severe space weather," points out [Doug] Biesecker. "The great geomagnetic storm of 1859, for instance, occurred during a solar cycle of about the same size we’re predicting for 2013."
The 1859 storm--known as the "Carrington Event" after astronomer Richard Carrington who witnessed the instigating solar flare--electrified transmission cables, set fires in telegraph offices, and produced Northern Lights so bright that people could read newspapers by their red and green glow. A recent report by the National Academy of Sciences found that if a similar storm occurred today, it could cause $1 to 2 trillion in damages to society's high-tech infrastructure and require four to ten years for complete recovery. For comparison, Hurricane Katrina caused "only" $80 to 125 billion in damage.