For the first time, model calculations show a plausible way that fluctuations in solar activity could have a tangible impact on the climate. Studies funded by the Swiss National Science Foundation expect human-induced global warming to tail off slightly over the next few decades. A weaker sun could reduce temperatures by half a degree.There is human-induced climate change, and there are natural climate fluctuations. One important factor in the unchanging rise and fall of the Earth’s temperature and its different cycles is the sun. As its activity varies, so does the intensity of the sunlight that reaches us. One of the key questions facing climate researchers is whether these fluctuations have any effect at all on the Earth’s climate. IPCC reports assume that recent solar activity is insignificant for climate change, and that the same will apply to activity in the near future.
Researchers from the Physical Meteorological Observatory Davos (PMOD), the Swiss Federal Institute of Aquatic Science and Technology (EAWAG), ETH Zurich and the University of Bern are now qualifying this assumption. Their elaborate model calculations are supplying a robust estimate of the contribution that the sun is expected to make to temperature change in the next 100 years. For the first time, a significant effect is apparent. They expect the Earth’s temperature to fall by half a degree when solar activity reaches its next minimum.
According to project head Werner Schmutz, who is also Director of PMOD, this reduction in temperature is significant, even though it will do little to compensate for human-induced climate change. “We could win valuable time if solar activity declines and slows the pace of global warming a little. That might help us to deal with the consequences of climate change.” But this will be no more than borrowed time, warns Schmutz, since the next minimum will inevitably be followed by a maximum.