Sun Makes History: First Spotless Month in a Century
Drop in solar activity has potential effect for climate on earth.
Michael Asher - September 1, 2008

The sun has reached a milestone not seen for nearly 100 years: an entire
month has passed without a single visible sunspot being noted.

The event is significant as many climatologists now believe solar magnetic
activity - which determines the number of sunspots -- is an influencing
factor for climate on earth.

According to data from Mount Wilson Observatory, UCLA, more than an entire
month has passed without a spot. The last time such an event occurred was
June of 1913. Sunspot data has been collected since 1749.

When the sun is active, it's not uncommon to see sunspot numbers of 100 or
more in a single month. Every 11 years, activity slows, and numbers briefly
drop to near-zero. Normally sunspots return very quickly, as a new cycle

But this year -- which corresponds to the start of Solar Cycle 24 -- has
been extraordinarily long and quiet, with the first seven months averaging a
sunspot number of only 3. August followed with none at all. The astonishing
rapid drop of the past year has defied predictions, and caught nearly all
astronomers by surprise.

In 2005, a pair of astronomers from the National Solar Observatory (NSO) in
Tucson attempted to publish a paper in the journal Science. The pair looked
at minute spectroscopic and magnetic changes in the sun. By extrapolating
forward, they reached the startling result that, within 10 years, sunspots
would vanish entirely. At the time, the sun was very active. Most of their
peers laughed at what they considered an unsubstantiated conclusion.

The journal ultimately rejected the paper as being too controversial.

The paper's lead author, William Livingston, tells DailyTech that, while the
refusal may have been justified at the time, recent data fits his theory
well. He says he will be "secretly pleased" if his predictions come to pass.

But will the rest of us? In the past 1000 years, three previous such
events -- the Dalton, Maunder, and Sprer Minimums, have all led to rapid
cooling. One was large enough to be called a "mini ice age". For a society
dependent on agriculture, cold is more damaging than heat. The growing
season shortens, yields drop, and the occurrence of crop-destroying frosts

Meteorologist Anthony Watts, who runs a climate data auditing site, tells
DailyTech the sunspot numbers are another indication the "sun's dynamo" is
idling. According to Watts, the effect of sunspots on TSI (total solar
irradiance) is negligible, but the reduction in the solar magnetosphere
affects cloud formation here on Earth, which in turn modulates climate.

This theory was originally proposed by physicist Henrik Svensmark, who has
published a number of scientific papers on the subject. Last year
Svensmark's "SKY" experiment claimed to have proven that galactic cosmic
rays -- which the sun's magnetic field partially shields the Earth from --
increase the formation of molecular clusters that promote cloud growth.
Svensmark, who recently published a book on the theory, says the
relationship is a larger factor in climate change than greenhouse gases.

Solar physicist Ilya Usoskin of the University of Oulu, Finland, tells
DailyTech the correlation between cosmic rays and terrestrial cloud cover is
more complex than "more rays equals more clouds". Usoskin, who notes the sun
has been more active since 1940 than at any point in the past 11 centuries,
says the effects are most important at certain latitudes and altitudes which
control climate. He says the relationship needs more study before we can
understand it fully.

Other researchers have proposed solar effects on other terrestrial processes
besides cloud formation. The sunspot cycle has strong effects on irradiance
in certain wavelengths such as the far ultraviolet, which affects ozone
production. Natural production of isotopes such as C-14 is also tied to
solar activity. The overall effects on climate are still poorly understood.

What is incontrovertible, though, is that ice ages have occurred before. And
no scientist, even the most skeptical, is prepared to say it won't happen

Article Update, Sep 1 2008. After this story was published, the NOAA
reversed their previous decision on a tiny speck seen Aug 21, which gives
their version of the August data a half-point. Other observation centers
such as Mount Wilson Observatory are still reporting a spotless month. So
depending on which center you believe, August was a record for either a full
century, or only 50 years.