Sun Takes Unprecedented Holiday

As the theory goes, lower magnetic activity of the sun lets more GCR’s into our solar system, which produce microscopic cloud seed trails (like in a Wilson cloud chamber) in our atmosphere, resulting in more cloud cover, resulting in a cooler planet. Ric Werme has a nice pictorial here.

When I saw the SWPC Ap geomagnetic index for Dec 2009 posted yesterday, my heart sank. With the sunspot activity in December, I thought surely the Ap index would go up. Instead, it crashed. _WUWT

Many of us were hoping that the modest resumption of sunspots in mid December -- after a few years of very rare sunspots -- would signal the sun's intention to "power up" to full strength. Unfortunately, an important measure of solar activity -- the geomagnetic index "Ap" -- has recently crashed to unprecedented levels. Ap is now too low to measure, for all practical purposes.

With the Ap index dwindling to a wisp of magnetism, it bolsters the argument made by Livingston and Penn that sunspots may disappear altogether by 2015. See Livingston and Penn – Sunspots may vanish by 2015....The theory goes that once the magnetic strength falls below 1500 gauss, sunspots will become invisible to us. _WUWT

According to the Svensmark cosmic ray theory, it is a low geomagnetic index -- such as we see now -- that allows galactic cosmic rays to penetrate the heliosphere, reaching Earth's atmosphere and inducing more cloud formation. More clouds tend to block solar rays, leading to a cooler climate. NASA has already predicted that the next solar cycle -- cycle 25 -- will have very low activity, as the solar conveyor slows. What NASA failed to see was that cycle 24 would have such low activity.

If multiple long, slow solar cycles begin to line up in a row -- like airliners waiting in a queue at Chicago's O'Hare -- Earth's climate may be in for a long, cold few decades.