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_ PopSci.com welcomes Dr. Bill Chameides, dean of Duke’s Nicholas School of the Environment. Dr. Chameides blogs at The Green Grok to spark lively discussions about environmental science, keeping you in the know on what the scientific world is discovering and how it affects you – all in plain language and, hopefully, with a bit of fun. PopSci.com partners with The Green Grok, bringing his blog posts directly to our users. Give it a read and get in on the discussion!_

Remember those sunspots that didn’t show up in 2008? All told, there were 266 days without a spot on the Sun last year. The most spot-free year for the Sun since 1913 (311 spotless days).

The fact that there were few sunspots in 2008 was not surprising — the Sun was at the minimum in its 11-year cycle. Over a cycle, the Sun’s output can vary by about 0.1 percent from what’s called the solar maximum to the solar minimum, and along with this variation in solar output there is a variation in the number of small black spots — called not surprisingly sunspots — that appear on the solar disk.

But no one expected this latest minimum to have been so strong (or should I say weak) and to have lasted so long.

New Sun Finally Snaps Out of It

The solar minimum finally did end. Sometime around December of ’08 the Sun woke up and began showing its spots with some regularity.

So the new solar cycle has begun, but it looks so weak as to look darn right pitiful. Peak activity is predicted to occur around May 2013 and “will be below average in intensity, with a maximum sunspot number of 90.”

By contrast, the maximum for the last cycle in 2000 occurred with a mean annual sunspot number of 120.

OK, Climate Skeptics, Here’s Your Chance

There are those who just can not accept that global warming is caused by greenhouse gases. For many of them, the warming must just be caused by the Sun getting “hotter.” Suffice it to say, I am not one them. But it does appear that the Sun has arranged an interesting experiment for us — a sort of climate showdown.

The last time a sunspot maximum even came close to being this low was in 1968 with a sunspot number of 106. Before that you have to go all the way back to 1928 when the maximum clocked a mean annual number of 78. (See sunspot index data.)

Global average temperatures in the late 1920s were about 0.6 degrees Celsius (1.1 degrees Fahrenheit) cooler than today and, in the late 1960s, 0.5 degrees Celsius (0.9 degrees Fahrenheit) cooler.

I guess if all the warming of the past century were due to the Sun — as many skeptics claim — we must be headed for some very, very cold temperatures in the coming decade. Let’s see what happens, shall we?

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