Sunspots and Climate Change
Is There a Connection Between Sunspot Activity and Global Cooling?
Sunspots increase and decrease through an average cycle of 11 years. Dating back to 1749, we have experienced 23 full solar cycles where the number of sunspots have gone from a minimum, to a maximum and back to the next minimum, through approximate 11 year cycles.
At times, however, sunspot numbers have remained quite low. These periods, known as minimums, have coincided with much cooler temperatures worldwide.
Historical Sunspot Minimums
Low sunspot numbers have been historically linked to global cooling several times over the past 500 years or so. Named for the German astronomer Gustav Sporer, the Sporer Minimum was a 90-year span from about 1460 until 1550 that was marked by abnormally low sunspot numbers. Like the subsequent Maunder Minimum and Dalton Minimum that would follow, the Sporer Minimum coincided with a time when Earth's climate was colder than average.
The Sporer Minimum occurred before sunspots had been directly observed and was discovered instead by analysis of the proportion of carbon-14 in tree rings, which is strongly correlated with solar activity.
The Maunder Minimum was a period roughly spanning 1645 to 1715 when sunspots became exceedingly rare, as noted by solar observers of the time. The period was named after the solar astronomer Edward W. Maunder (1851–1928).
During one 30-year period within the Maunder Minimum, astronomers observed only about 50 sunspots, as opposed to a more typical 40,000–50,000 spots in modern times. More importantly, the Maunder Minimum coincided with the coldest part of the Little Ice Age, during which Europe, North America, and much of the rest of the world experienced bitterly cold winters and very cool or no summers.
During the Little Ice Age, global temperatures dropped sharply. Stories and anecdotes claim New York harbor froze solid enough to allow people to walk from Manhattan to Staten Island, and in Britain, people reported sighting Eskimos paddling canoes off the coast. Glaciers in Norway supposedly grew up to 100 meters a year, destroying farms and villages.
The Dalton Minimum was also a period of low sunspot activity. Named for the English meteorologist John Dalton, this minimum lasted from about 1790 to 1830. As with the Maunder Minimum, the Dalton Minimum coincided with a period of lower-than-average global temperatures. Some weather reporting stations, for example, experienced a 2.0 degree C decline over 20 years. While that sounds like a small decline over a long time period, in the reality of the entire planet that represents a drastic drop in temperature over a very short time frame. Coincidentally, the Year Without a Summer, in 1816, also occurred during the Dalton Minimum.
Is the Earth Cooling?
"Disconcerting as it may be to true believers in global warming the average temperature on earth has remained steady or slowly declined during the past decade, despite the continued increase in the atmospheric concentration of carbon dioxide, and now the global temperature is falling precipitously”
(Phil Chapman Australian astronaut, geophysicist, and aeronautical engineer)
Four agencies that track earth's temperature-the Hadley Climate Research Unit in Britain, the NASA Goddard Institute for Space Studies in New York, the Christy group at the University of Alabama, and Remote Sensing Systems Inc in California-report that the planet cooled by about 0.7 degree C in 2007. This is the fastest temperature change (drop) since science began instrumental record keeping and seems to sets global temperatures back to where they were in 1930.
There is also plenty of anecdotal evidence that 2007 was exceptionally cold, most notably that it snowed in Baghdad for the first time in centuries, the winter in China was bitter and the extent of Antarctic sea ice in the austral winter was the greatest on record since James Cook discovered the place in 1770.
The trend continued in 2008. The National Weather Service reports that the summer of 2008 was Alaska’s third coolest on record, while the National Snow and Ice Data Center found that Arctic sea ice expanded 13.2 percent in 2008, or a Texas-sized 270,000 square miles.
In September, 2008 snow graced the southern provinces of Brazil for the first time during an especially cold month and in December, 2008 a ferocious ice storm hammered New Englanders while up to eight inches of snow struck New Orleans and southern Louisiana. In the same month, Southern California had half an inch of snow in the Malibu hills while six inches was enough to maroon commuters in desert towns east of Los Angeles.
It must be noted that while some prominent scientists firmly believe there is a link between sunspot activity and global cooling, a definite causal connection has yet to be proven. Is the planet headed for another Maunder Minimum or will cycle 24 finally ramp up as predicted? Time will tell.
Does Solar Activity Cause Climate Change?
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