And other some have been even more direct: no/few sun spots = dangerous global cooling.
The sun undergoes cyclical changes on multiple time scales that appear to correlate very well with temperatures. Long and relatively quiet solar cycles historically have been associated with cold global temperatures, short and very active cycles, warm periods. The current cycle 23 appears to be the longest in at least a century and may project to quieter subsequent cycles and cooling temperatures ahead.
Except: how unusual is a situation like the current one really? Not very, according to NASA's David Hathaway:
"There have been some reports lately that solar minimum is lasting longer than it should. That's not true," said NASA solar physicist David Hathaway. The ongoing lull in sunspot numbers "is well within historic norms for the solar cycle.
"The sun has been relatively quiet for more than two years. Hathaway said there were stretches in the 20th century when the slack periods lasted twice this long.
"It does seem like it's taking a long time," Hathaway said, "but I think we're just forgetting how long a solar minimum can last."
And here's a chart that compares the latest minimum in terms of "spotless days" to the 1933 minimum. Contra D'aleo (2nd quote above) our current quiet period is not even close to being the longest observed minimum this century:
Another way to examine the length and depth of a solar minimum is by counting spotless days. A "spotless day" is a day with no sunspots. Spotless days never happen during Solar Max but they are the "meat and potatoes" of solar minima.
Adding up every daily blank sun for the past three years, we find that the current solar minimum has had 362 spotless days (as of June 30, 2008). Compare that value to the total spotless days of the previous ten solar minima: 309, 273, 272, 227, 446, 269, 568, 534, ~1019 and ~931. The current count of 362 spotless days is not even close to the longest.
Cycle that, Anthony.