So, how strongly does the sun currently influence the climate? What is known is that Earth has become warmer by around one degree Celsius over the past 100 years. In the last 30 years alone, temperatures have increased at a rate not seen during the last 1000 years. It is another fact that the carbon dioxide concentration has increased by 30 percent since industrialization began in the mid-18th century.

During this entire period, the sun has been subject to periodic fluctuations in activity. And there has certainly been no increase in the brightness of the sun over the past 30 or 40 years, rather a slight decrease. This means that the sun cannot have contributed to global warming. In fact, the temperature increase noted in recent decades cannot be reproduced in models if only the influence of the sun or other natural sources are taken into account (for example volcanic eruptions). Only when anthropogenic, that is human-driven, factors are incorporated in the climate data, do they agree with the observational and measured data.

The researchers thus arrive at the conclusion that the increase in global temperatures since the 1970s cannot be explained by the sun. The observed temperature trend over the past three decades is linear – if it is a result of the increasing greenhouse gas concentration. In brief: the human influence on the climate is orders of magnitude greater than that of the sun.

On the other hand, the opinion of some scientists that the current decrease in solar activity will counteract global warming, does not stand up to a close examination, as global warming is a fact—and continues to advance. In contrast, it does appear possible that the sun influences the climate in the long term. The exact extent and precise mechanisms remain unclear, however.