For students of the Sun, the length of the solar cycle, which lasts an average of 11 years but may go longer or shorter, has proven the best historical indicator of short-term climate. At the ends of these solar cycles, sunspot activity first declines, and then picks up markedly, indicating the beginning of a new cycle. The precise relationship between the sunspots, which are thought to be determined by magnetic activity within the Sun, and the energy output of the Sun are not known. However, long‐term studies of the historical record have shown that when the minimum sunspot activity extend beyond the average 11 years, significant declines in temperatures on Earth are experienced.
And this, from Spaceweather.com:
The sun is in the pits of a very deep solar minimum. Many researchers thought the sunspot cycle had hit bottom in 2008 when the sun was blank 73% of the time. Not so. 2009 is on the verge of going even lower. So far this year, the sun has been blank 75% of the time, and only a serious outbreak of sunspots over the next few weeks will prevent 2009 from becoming the quietest year in a century. Solar minimum continues.
I would have thought that being in such a deep solar minimum would be good for communications, but it turns out (see the chart at the top) that sunspots increase solar winds that brush galactic cosmic rays away from Earth. Without sunspots, the solar winds are very low and more cosmic rays enter the Earth's atmosphere to interfere with communications. Read the article on page 28 of World Radio Online for a nice description.
In short, even though the Al Gores and James Hansons of the world have been shouting for years about the sky falling, we've actually had it very good. What's coming, hard winters, lower food production and poor communications, could be quite an eye opener.
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