In 1610 Galileo observed dark features on the face of the sun – sunspots. In the preface to a little book Galileo wrote on sunspots that was published in 1613, he was credited with having discovered sunspots but an Englishman, Thomas Harriott, and a Dutchman, Johann Fabricius, probably beat him to that discovery.
What we do know is that since the invention of the telescope, Europeans have been keenly observing sunspot activity and some have been correlating it with global temperatures.*
The US National Oceanic and Atmospheric Administration (NOAA) publishes the mean monthly sunspot number back to January 1749.
There were no sunspots during a period of unusual cold in the northern hemisphere known as the Maunder Minimum which extended some 70 years from 1645 to 1715.
Because the number of sunspots has shown a general trend of decline since March 2006 there has been much chatter amongst global warming skeptics with some suggesting that we are perhaps in for an extended period of cooling
Now there is more excitement, because August 2008 appears to be the first month since June 1913 without a sunspot.
[But perhaps I should wait until there is a zero recorded at the official NOAA site before announcing this?]
David H. Hathaway, Solar Physics Team Leader at the NASA Marshall Space Flight Center in Huntsville, has suggested that this solar cycle 24 is just taking a while to get started.
Habibullo I. Abdussamatov, head of the space research laboratory of the Russian Academies of Sciences’ Pulkovo Observatory and of the International Space Station’s Astrometry project, has predicted for some time that because of low solar activity we may be entering another period similar to the late 17th century and that this may start in 2012-2015 and reach its peak in 2055-2060.**
* Why few sunspots could correlate with low tempertures by Richard Mackey:
“The Earth’s geomagnetic field provides a buffer against solar radiation, the solar wind and radiation of all types generated elsewhere in the Universe. The field’s strength depends on solar output and the lunisolar tides. A stronger geomagnetic field will deflect more cosmic radiation than a weaker one.
“A highly active Sun can make the geomagnetic field stronger; a relative inactive Sun will make it weaker. Other things being equal, a strong geomagnetic field contributes to a warmer climate; a weaker field to a cooler climate. But the effect may not be uniform across the planet. Currently, the geomagnetic field seems to be weakening, contributing to global cooling.
“The heliosphere, and the termination shock sphere within it, deflects cosmic radiation. The Earth’s geomagnetic field also deflects cosmic radiation. The strength of the heliosphere depends on the Sun’s activity levels. High levels of solar activity reduce the volume of cosmic rays entering the Earth’s atmosphere, contributing to global warming. High levels of solar activity generate more turbulence in the heliosphere scattering galactic cosmic rays before they reach the inner planets. Conversely, a greater volume of cosmic rays enter our atmosphere during times of low solar activity because the Heliospheric magnetic fields are smoother with less scattering of galactic cosmic rays, resulting in global cooling.”
(from ‘Much more to the Earth’s Climate than human activity’, Submission to the Garnaut Climate Change Review by Richard Mackey, February 2008)
** Lawrence Solomon profiled Dr Abdussamtov in a piece entitled Look to Mars for the truth on global warming, The Deniers — Part IX, Financial Post Published: Friday, February 02, 2007.
Published papers by Dr Abudssamotov predicting cooling include: ‘Optimal Prediction of the Peak of the Next 11-Year Activity Cycle and the Peaks of several Succeeding Cycles on the basis of Long-Term Variations in the Solar Radius or Solar Constant’, Kinematics and Physics of Celestial Bodies, 2007, Vol. 23, No. 3, pp 97-100, and ‘Long-Term variations of the Integral radiation Flux and Possible Temperature Changes in the Solar Core’, Kinematics and Physics of Celestial Bodies, Vol. 21, No. 6, pp. 328-332, 2005.