When we think of climate change or global warming, we hear a lot of different causes. Some would say that it is just normal part of the sun’s cycles. However, do any of the sun’s cycles explain the latest warming that the Earth has been experiencing since around 1975?
There are several cycles that the sun experiences, all of which alters the solar radiation that reaches and can change the Earth’s climate. The sun is not a static star, but experiences its own natural changes.
The first cycle the sun goes through is sunspots. The sun spot cycle occurs every 11 years. Sunspots do not stay in one place on the sun, but move around depending on the temperature changes that occur around the sun. When a spot on the sun becomes extremely hot, a spot becomes dark, known as a black body. Since 1979, more sunspots have been observed with an increase of solar radiation and intensity. But this only accounts for an increase in 0.1 percent.
Eccentricity is the second cycle the sun experiences. Eccentricity occurs roughly every 100,000 years and determines the shape of the Earth’s orbit around the sun. When the Earth’s orbit becomes more elliptical, the Earth will receive more solar radiation from the sun, because it is closer to the sun. This cycle will give us mild or cold winters, and hotter summers depending on the orbit and axis of the Earth. The solar radiation would also be dependent on which hemisphere you lived in for the climate change. The current climate change is global, so eccentricity cannot be blamed for the current climate change. Also, we are currently in a rather low eccentricity, which should cool the planet down rather than warm it.
A third cycle is called Obliquity, which takes about 41,000 years to complete its cycle. Obliquity is when the Earth’s axis changes its tilt. Obliquity can shift the Earth’s axis from 22.1‹ to 24.5‹ and back. In laments terms, this effects the Earth’s seasons. Luckily, we are currently at an axis tilt of about 23.44‹, which is between the extremes that could potentially cause humans problems with survival, based on agricultural perspectives. However, obliquity cannot be blamed for the current climate change.
Finally, the sun also experiences a cycle that takes 23,000 years called, Precision. Precision wobbles the Earth around on its axis, and effects how extreme the seasons are, as well as obliquity. Precision cannot be blamed for global climate change either; since it effects the seasons differently depending on which hemisphere is closer to the sun on the time of the cycle.
While the sun cycles do affect the climate on longer timescales, it does not have any bearing on the current climate change that has been going on since 1975. This gives more evidence to the theory that the current, rapid climate change is man-made.