The sun is now in an unusually long quiet period with a lack of sunspots. In the past, in what is known as the Maunder minimum, there was a long period of little or no sunspot activity. This coincided with what is called The Little Ice Age. During this time there was a noticeable cooling in Europe and North America and many glaciers began to advance. People ice skated on the Thames in London. Settlers in northern regions had to relocate to warmer zones.
But nobody has ever given a mechanism to explain how a lack of sunspots could cause a cooler climate. Recently, some Danish scientists proposed a mechanism. No sunspots mean less magnetic activity from the sun since sunspots represent solar magnetic storms. Less magnetic activity from the sun, in turn, causes lower magnetic activity on the planets. It is the Earths' magnetic field that steers many cosmic rays away from our planet.
With a weaker magnetic field here on earth, more cosmic rays penetrate the atmosphere. These high energy rays cause the formation of ionized particles which serve as nuclei around which cloud droplets can form.
The result is more clouds which reflect solar energy back into space. With less solar heat, the atmosphere cools.
Many scientists dispute this theory but there still seems to be a connection with solar activity and climate.
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