Sunspots are storms or cooler areas on the surface of the sun whose magnetic radiation is about 2500 times that of the earth. Due to the strong magnetic field, the spot experiences very high pressure relative to the surrounding atmosphere. This lowers the temperature of the sunspot. The sunspot is dark compared to the surrounding bright areas. Sunspots are believed to change in a cycle of 11 years (Noss, 2009). The question of whether sunspots cause climatic changes on the earth surface has been a controversial one for quite some time. Recently however, evidence to support this has been steadily increasing.
In the past, periods of low sunspot activity have coincided with very cool climates suggesting that there is a link to sunspot activity and climate for example the Maunder Minimum a season in which sunspot activities were very rare (Holley, 2009).
The sunspot cycles seem to have different effects. When the sunspot cycle is at its peak, there is an increased ultraviolet radiation and a bit of increase in the solar energy. There are two mechanisms that work hand in hand to produce the climatic changes. These are called the top down and the bottom up mechanisms. In the bottom up mechanism, the extra energy from the sun leads to loss of water from the lakes through evaporation. Fewer clouds are formed in the subtropics and solar energy reaching the ocean is increased facilitating a feedback mechanism. In the top up mechanism, excess solar energy results in changes in the upper atmosphere. These result in precipitation in the tropics. The two mechanisms work together to the rising of tropical air which occurs through evaporation (Zielinski, 2009).
Further explanation is provided by Kemm (2008). According to Kemm, the mechanism of sunspots affecting climate change is based on cosmic rays' impact on the surface of the earth from the space. When the cosmic rays reach the earth and penetrate the atmosphere, they facilitate the forming of a cloud cover. This is by nucleating specific areas in the atmosphere. Clouds form in these areas or sites through condensing of the natural water vapor. The magnetic field of the earth which plays the role of a shielding is influenced by the sun's magnetic activity which is influenced by the number of sunspots for example, when the sunspots are many, the magnetic radiation of the sun is increased which creates an effect on the earth's magnetic shield.
The varying of the magnetic field of the earth causes consequent variation in the cloud cover. When the sunspots are few, the magnetic shield of the earth is weak. More cosmic rays reach the earth increasing the cloud cover and thus cooling the earth. When the sunspots are more, the magnetic shield of the earth is very strong. Fewer cosmic rays reach the earth and the cloud cover is very small thus there is more heat on the surface of the earth (Kemm, 2008).
Even though recent evidence has tried to show the role sunspots play in climatic changes, climatic changes cannot be pinned entirely on sunspots. This is because the climatic changes seem to be influenced by numerous other things in nature other than the solar system factors. However, the role that sunspots play in climatic changes cannot be neglected.