The sunspot cycle is about to come out of its depression, if a newly discovered mechanism for predicting solar cycles – a migrating jet stream deep inside the sun – proves accurate.  And that will add a small amount of warming in the next few years, which were already predicted to be record-setting by two recent studies.

When we last looked at the sun [please, don’t try that at home], we were at “a 12-year low in solar ‘irradiance’.”  As NASA explained in April:  “the sun’s brightness has dropped by 0.02% at visible wavelengths” since the solar minimum of 1996, which was “not enough to reverse the course of global warming.”  It’s been “the quietest sun we’ve seen in almost a century,” said sunspot expert David Hathaway of the Marshall Space Flight Center.

The deniers have been rooting for a Maunder Minimum to stifle global warming (which it wouldn’t have done anyway, see here).  But human-caused global warming is so strong that not bloody much stifling has been going on given that “this will be the hottest decade in recorded history by far,” nearly 0.2°C warmer than the 1990s.  Heck, even with a La Niña and an unusually inactive sun, 2008 was almost 0.1°C warmer than the decade of the 1990s as a whole – and of course the 1990s were, at the time, the hottest decade in recorded history.  Changes in the sun just ain’t the big dog anymore when it comes to driving climate change (see here).

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Yesterday, NASA reported remarkable news, “Mystery of the Missing Sunspots, Solved?“:

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June 17, 2009: The sun is in the pits of a century-class solar minimum, and sunspots have been puzzlingly scarce for more than two years. Now, for the first time, solar physicists might understand why.

At an American Astronomical Society press conference today in Boulder, Colorado, researchers announced that a jet stream deep inside the sun is migrating slower than usual through the star’s interior, giving rise to the current lack of sunspots.

Rachel Howe and Frank Hill of the National Solar Observatory (NSO) in Tucson, Arizona, used a technique called helioseismology to detect and track the jet stream down to depths of 7,000 km below the surface of the sun. The sun generates new jet streams near its poles every 11 years, they explained to a room full of reporters and fellow scientists. The streams migrate slowly from the poles to the equator and when a jet stream reaches the critical latitude of 22 degrees, new-cycle sunspots begin to appear.

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Above: A helioseismic map of the solar interior. Tilted red-yellow bands trace solar jet streams. Black contours denote sunspot activity. When the jet streams reach a critical latitude around 22 degrees, sunspot activity intensifies. [more graphics]

Howe and Hill found that the stream associated with the next solar cycle has moved sluggishly, taking three years to cover a 10 degree range in latitude compared to only two years for the previous solar cycle.

The jet stream is now, finally, reaching the critical latitude, heralding a return of solar activity in the months and years ahead.

“It is exciting to see”, says Hill, “that just as this sluggish stream reaches the usual active latitude of 22 degrees, a year late, we finally begin to see new groups of sunspots emerging.”

The current solar minimum has been so long and deep, it prompted some scientists to speculate that the sun might enter a long period with no sunspot activity at all, akin to the Maunder Minimum of the 17th century. This new result dispells those concerns. The sun’s internal magnetic dynamo is still operating, and the sunspot cycle is not “broken.”

If Solar Cycle 24 is going to rev up soon, it won’t affect global temperatures quickly.  NASA explained in January:

Because of the large thermal inertia of the ocean, the surface temperature response to the 10-12 year solar cycle lags the irradiance variation by 1-2 years. Thus, relative to the mean, i.e, the hypothetical case in which the sun had a constant average irradiance, actual solar irradiance will continue to provide a negative anomaly for the next 2-3 years.

Also, Solar Cycle 24 has recently been predicted to be on the wimpy side.

No, it’s a long and strong El Niño that would give us a global temperature record this year or next.

But when you put everything together – record, rapidly rising GHG concentrations, neutral or positive ENSO, and a return to the normal solar cycle – then you get what the peer-reviewed scientific literature has forecast:

  • The “coming decade” (2010 to 2020) is poised to be the warmest on record, globally.
  • The coming decade is poised to see faster temperature rise than any decade since the authors’ calculations began in 1960.
  • The fast warming would likely begin early in the next decade – similar to the 2007 prediction by the Hadley Center in Science (see “Climate Forecast: Hot – and then Very Hot“).