Sunspots by definition have nothing to do with AGW, but as an unusually spotless sun continues to puzzle scientists, get ready for yet another outbreak of pseudo-scientific man-made global warming denialism.
Q: Why is a ‘blank’ sun unusual?
A: The sun has been ‘spotless’ for 48 consecutive days. If this continues until 1 September, it will equal the longest period it was devoid of sunspots in 2008, and will be two years late in making the transition to a more active sun normally associated with the solar cycle.
Already the spectre of another ‘little Ice Age’ or at the very least, the total exposure of the evil plot by the IPCC and social engineers to use climate change to grab power and destroy free markets and democracy and Shell and Exxon is being touted around the fringes of climate change commentaries.
Yes. The sun is behaving very unusually. No, this doesn’t support the view that therefore all global warming has been solar driven and that the massive release of fossilised carbon through coal and oil combustion is totally exonerated as the reason why this winter hardly happened over most of Australia.
Q: What is a solar cycle and why is this one so odd?
A: The ‘normal’ solar cycle lasts approximately 11 years, and is measured between consecutive minimums of solar activity thus including a peak output of energy roughly 5.5 years after it begins followed by a similar period of decline.
However the previous cycle, number 23, has sunk into a prolonged period of low activity, so low some observers argue that cycle 24 hasn’t really taken over, meaning that cycle 23 which began just after the last minimum in 1996 has now been running for at least 13 years, or two years longer than normal, something last seen 96 years ago.
Q: What are sunspots and what do they tell us about the sun?
A: The number of sunspots and their frequency are a near perfect indication of the cyclical progression of solar energy variations. More spots, more energy.
Sunspots are areas of intense magnetic activity that causes localised reductions of the temperature of the sun’s surface, hence a darker spot. Their correlation with solar activity includes ultraviolet and soft x-ray emission levels, which in turn have important effects on the behaviour of the earth’s upper atmosphere.
Q: Do they directly affect heat energy from the sun?
A: Yes, but not enough to directly affect the weather. In this deep solar minimum the luminosity of the sun has declined by around 0.02% according to most studies.
However research has not yet definitively found, described or measured other mechanisms by which variations in energy emitted by the sun translate into warming or cooling influences by changing the cloud cover to either retain or deflect radiant energy, or by exerting subtle yet significant cumulative effects on oceanic weather mechanisms like the Pacific Decadel Oscillation.
In this deep solar minimum ultraviolet radiation from the sun is down by 6% compared to the lowest intensity recorded during the previous solar minimum in 1996. This is unusual, but is nevertheless a very small widening of the 1.5% spread observed between upper and lower UV radiation output in a ‘normal’ solar cycle.
It also follows the damage done by fossil carbon releasing global warming, not precedes it. There is no connection.
This is also the first deep or extended solar minimum that has ever been studied by more than ground based visible wavelength telescopes. Since the beginning of radio and other non visible wavelength astronomy, and the launching of satellites able to directly observe the solar polar regions and its far side, the sun has been comparatively more energetic than normal in terms of sunspots counts.
Almost no-one alive, and certainly no-one conducting solar research, has ever seen a sun this ‘blank’ or quiet.
Q: What happened in the previous deep solar minimums?
A: The last two comparable and even deeper solar minimums reached their nadirs in 1901 and 1913. There were no obvious cooling effects on the global weather reports, (in so far as they were reported) and in between those ‘blank’ suns Europe experienced some unusually balmy summers that were popularly attributed to the surprise appearance of several ‘great comets’ plus a predicted and bright approach by Halley’s Comet in 1910.
Dr David Hathaway, the leader of the heliophysics team at NASA’s Marshall Space Flight Center, said the current solar minimum would only surpass the depths of 1901 and 1913 if it persisted with negligible sunspots until next April.
However the next deep solar minimum working back in time from the early 20th century was the Dalton Minimum, a term applied to a succession of low sunspot producing cycles from 1790-1830, during which temperatures across Europe fell, and included the ‘year without summer’ of 1816, later attributed to a massive volcanic eruption in Indonesia that reduced sunlight across the northern hemisphere.
The Dalton Minimum is also the nearest example of more than two consecutive deep solar minimums to modern times.
The most infamous sets of spotless or almost spot free solar cycles observed by astronomers were those of the Spörer Minimum (1460-1550) and Maunder Minimum (1645-1715) the latter coinciding with the peak severity of the so called Little Ice Age that gave middle and western Europe winters almost as bad as Russia experiences to this day.
Q: Would another ‘Dalton’ minimum save us from global warming?
A: No-one knows. However several years ago Dr James Hansen, the director of the Goddard Institute of Space Studies, pointed out that rising concentrations of greenhouse gases could inhibit natural cooling cycles because of the long dwell time of excess carbon dioxide in the atmosphere.
When the Dalton Minimum occurred, the concentration of carbon dioxide in the atmosphere was less than 284 parts per million. By 1901 it was 296 ppm and in 1913 crossed the 300 ppm line. In whatever name is given to this minimum, CO2 is present at more than 390 ppm in 2009.
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