Sunspot data has been collected since 1749. Now the job is handled by Mount Wilson Observatory, which is part of UCLA - this pic was taken minutes ago.
Sunspot activity on the face of the sun that we can see is cyclical - we are now at the start of Solar Cycle 24 . It is uncommon / rare for no sunspots to be visible but in the whole of August 2008 not a single sunspot has been recorded (last such even June 1913) - this follows 7 months when the average sunspot number has been 3. (NOAA claim a "half/spot" has been seen in August - Mount Wilson disagree.) Also check out monthly report from Solar Influences Data Analysis Centre SIDA part of Royal Belgian Observatory
The 11-year sunspot cycle is not built symmetrically. The ascending part from minimum to maximum is shorter than the declining part from maximum to minimum.
This apparent lack of solar activity has caught astronomers on the hop. However 2 authors based at the National Solar Observatory (NSO) in Tucson AZ. proposed, in a paper in 2005 , eventually refused publication in the respected journal Science ,that from observed minute spectroscopic and magnetic changes they could reasonably extrapolate that within 10 years sunspots would vanish completely.
In the past millenium there have been 3 such "Maunder Minimum" events Dalton, Maunder, and Spörer Minimums, have all led to rapid cooling. One was large enough to be called a "mini ice age".
Whilst agriculture evidently needs heat for crop growth, cooling produces shorter growing seasons , crop yields drop accelerated by autumn frosts.
Therefore the gloomy summers experienced in the last few years in the UK may be explained by the sun's dynamo slowing down . Anthony Watts a meteorologist explains that 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.
Clouds have a hundred times stronger effect on weather and climate than carbon dioxide in the atmosphere. H. E. Landsberg has shown that if the atmosphere’s carbon dioxide content doubled, its effect would be cancelled out if the cloud cover expanded by 1%. (Landsberg, H. E.: Man-made climatic changes. In: Proceedings of the symposium on physical and dynamic climatology of the World Meteorological Organization 347 (1974), 262.)
It seems remarkable but the study of clouds, and their origins is imperfectly understood. Physicist Henrik Svensmark, claims 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.he says this is a more significant factor in climate change than greenhouse gases.
Briefly , when the solar wind is strong and cosmic rays are weak, the global cloud cover shrinks. It extends when cosmic rays are strong because the solar wind is weak. This effect, attributed to cloud seeding by ionized secondary particles, causes a change in cloud cover by more than 3 % within 3 ½ years.
Ilya Usoskin is a solar physicist at the University of Oulu, Finland, says the equation "more rays equals more clouds" is a simplification and points out the effects are not global but are more important at certain latitudes and altitudes which control climate.
J. E. Hansen who is a renowned cheer leader and protagonist of global warming said in 1998 (Hansen, J. E., Sato, M., Lacis, A., Ruedy, R., Tegen, I., and Matthews, E.: Climate forcings in the industrial era. Proceedings of the National Academy of Sciences 95 (1998), 12753-12758:
"The forcings that drive long-term climate change are not known with an accuracy sufficient to define future climate change ... The natural forcing due to solar irradiance changes may play a larger role in long-term climate change than inferred from comparisons with general circulation models alone."
Nigel Calder pointed out in the Times Feb 11th 2007 The best measurements of global air temperatures come from American weather satellites, and they show wobbles but no overall change since 1999. The silence of the IPCC lobby remains silent on this unpersuasive and inconvenient Truth.
This was immediately prior to his publication of, "The Chilling Stars: The New Theory of Climate Change " by Henrik Svensmark and Nigel Calder Amazon billed as "Nigel Calder has provided a very readable explanation of how solar activity affects climate change"
Calder attacks the agreed and current consensus on the role of anthropogenic greenhous gases. Of course non scientific , non peer reviewed souls must not upset the IPCC whose real reason is to increase the size and scope of government, and centralizing power. You notice the alarmism, and their call for "something to be done about it," meaning for individuals to give up freedom and conveniences and for government to increase taxes and regulation. We posted about this Friday, March 09, 2007 The climate on the climate change crisis is changing
But thats's another story ... Meanwhile lets just have a look at the sun - naked.
PS SOHO sun images here SIDA sunspot cycles here as Gemma says, to make them bigger simply click on them.