There are no visible sunspots on the most current solar image; courtesy NASA/SDO, spaceweather.com
Meteorologist Paul Dorian shares some thought on the impact when spots vanish, the potential for a grand minimum.
Finally, if history is any guide, it is safe to say that weak solar activity for a prolonged period of time can have a cooling impact on global temperatures in the troposphere which is the bottom-most layer of Earth’s atmosphere – and where we all live. There have been two notable historical periods with decades-long episodes of low solar activity. The first period is known as the “Maunder Minimum”, named after the solar astronomer Edward Maunder, and it lasted from around 1645 to 1715. The second one is referred to as the “Dalton Minimum”, named for the English meteorologist John Dalton, and it lasted from about 1790 to 1830 (above).
Both of these historical periods coincided with colder-than-normal global temperatures in an era that is now referred to by many scientists as the “Little Ice Age”. One of the reasons prolonged periods of weak solar activity may be associated with colder global temperatures has to do with a complicated relationship between solar activity, cosmic rays, and clouds on Earth. Research studies in recent years have found that in times of low solar activity – where solar winds are typically weak – more cosmic rays reach the Earth’s atmosphere which, in turn, has been found to lead to an increase in certain types of clouds that can act to cool the Earth.
Paul Dorian’s conclusion:
This historically weak solar cycle continues the recent downward trend in sunspot cycle strength that began over thirty years ago during solar cycle 22. If this trend continues for the next couple of cycles, then there would likely be increasing talk of another “grand minimum” for the sun which correlates to an extended decades-long period of low solar activity. Some solar scientists are already predicting that the next solar cycle will be even weaker than this current one which has been historically weak. However, it is just too early for high confidence in those predictions since many solar scientists believe that the best predictor of future solar cycle strength involves activity at the sun’s poles during a solar minimum phase – something we are now rapidly approaching – and the current blank look to the sun is liable to become more and more frequent in the months to come.
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