The sun goes through natural cycles, which have been understood and recorded since 1843, when Heinrich Schwabe recognized an 11.1-year solar cycle. So, we know that the sun has an effect on global warming, but further research suggests that this effect is minimal.
In another article in this series, I talked about how the earth has been going through warming and cooling cycles for millions of years. In this article, I will discuss how the sun fits into these warming and cooling cycles, as well as the fact that the sun has its own cycle that many believe has its own warming and cooling effect on the earth.
The first important thing to realize is that many of the Earth’s warming and cooling cycles talked about in another article are long-term cycles, whereas the sunspot activity cycles we see on the sun are short-term cycles which can be superimposed onto this long-term cycle. It’s also important to realize that the long-term cycles are not really based on solar causes, at least for the most part.
The long-term cycles are really based on carbon dioxide levels, the amount of ice and snow covering the planet, the amount of the planet’s surface which is covered with oceans and seas, which can change based on sea levels, and most importantly the amount of vegetation and forest covering the planet, which can absorb heat and carbon dioxide. These different things interact with each other in complicated ways. It is possible that the sun influenced these long-term cycles, but only if the sun worked to amplify the dynamics which were already taking place on the earth. Most likely, though, since the solar cycles were shorter cycles, they didn’t have too much influence on the longer cycles.
There is one caveat, though. Over the course of the last 4 million years, there have been many times that the temperature of the planet has swung from a cool period to a warm period, or vice versa, and many times those swings in temperature correlate to fluctuations in the tilt of the earth’s axis, or the shape of its orbit around the sun, or the influence of the moon’s gravity, as well as possibly the other planets. From this standpoint, especially when it comes to tilt and orbit, these factors help to change the sun’s influence on the earth, leading to these long-term cycles, but only indirectly.
Back to the 11-Year Cycle
Anyways, let’s get back to the 11.1-year solar cycle as discovered by Heinrich Schwabe in the nineteenth century. Although sunspots were first noticed by observers since the early 1600’s, it was Schwabe who first realized that sunspot activity goes through an 11-year cycle.
Now these days there are many people who look at this sunspot cycle and say that some of the hot years that we have are due to the sunspot cycles, and its effect on Earth’s climate and temperature.
The problem, though, is that when you look at the evidence, or should I say lack of evidence, this is very likely not the case.
For example, according to one group of researchers, the variation in ultraviolet (UV) radiation between solar maximum and solar minimum correlates with a variation of only 0.18 K ±0.08 K (0.32 °F ±0.14 °F) in measured average global temperature – that’s less than half of a degree of variation, which isn’t very much.
Another observation that has been made is that the solar activity in the 2010’s solar cycle was no more than the amount of solar activity that was found in the 1950’s solar cycle – from that standpoint, there should have been the same higher temperatures during that 1950’s cycle as there was during the 2010’s cycle, but that was not the case. The global temperatures in the 2010’s cycle was definitely higher than it was more than half a century earlier, which would suggest that there must be some other factors driving that higher temperature than the solar cycle. It is believed that increasing greenhouse gasses is the probable culprit, not the sun and its cycles.
Conclusion
So, we can conclude that the probability of the sunspot cycles having a significant effect on climate change and global temperature increases is very little, if none at all.
But, let’s get back to the last point I made, that increasing greenhouse gasses are more likely to have caused the increase in global temperatures than the solar cycle.
