By Frank Bosse and Fritz Vahrenholt
(Translated/edited by P Gosselin)
In August 2015 solar activity was also weak, only 71% of the mean activity that is usual for this month into the cycle. The solar sunspot number (SSN) was 64.6. The mean for the previous 23 cycles is 91. The course of the current cycle so far is depicted in Figure 1:
Figure 1: The solar sunspot number (SSN) for the current solar cycle number 24 is shown in red; the average of the previous 23 cycles is shown in blue; and the similar solar cycle number 5 is shown in black.
The current cycle increasingly resembles solar cycle no. 5, which took place from 1798 to 1810, i.e. in the middle of the Dalton Minimum. That cycle was very long at 12.6 years, which is what we are expecting for the current cycle. As a rule weak cycles are longer than the cycles that see strong solar activity. The summed up monthly anomalies, i.e. the accumulated monthly differences for the current cycle compared to that of the mean value shown by the blue curve in Figure 1, has been the most negative since the Dalton Minimum.
Figure 2: The accumulated SSN anomalies plotted for all cycles 1-24 compared to the mean. The decline in solar activity since cycle no. 22 (which persisted until 1996) is clear to see.
At this blog we reported on a number of occasions on the relationship between solar activity and the North Atlantic Oscillation (NAO). Already in our book “The Neglected Sun“ we quoted a paper by Lockwood who found a strong statistical correlation between solar activity, the NAO and cold British winters. Many other studies have since appeared and further confirm this correlation for Northern Europe. As a reminder: The NAO is calculated as the atmospheric air pressure difference between Reykjavik and the Azore.
In September 2015 another paper was published by scientists Katja Matthes and Remi Thieblemont of the Geomar Center for Ocean Research, appearing in Nature Communications. According to their findings the North Atlantic Oscillation lags solar activity by 1 to 2 years. The scientists used a climate model that simulated the atmosphere at an elevation of up to 14o km and thus were able to better account for the effect of UV radiation on the chemistry of the stratosphere, like ozone composition.
Naturally we know that we have to be careful with the results of models. We’ve documented to a great extent the failure of a huge number of numerical models. What is remarkable, however, is that conventional climate research has since found that the impact of the sun on our climate is relevant. Up to now much effort has been expended to talk down the sun’s impact, claiming that the sun’s total solar irradiance (TSI) varies only by about 0.1% during a cycle. But the UV part of the solar radiation spectrum in the stratosphere have huge radiation effects of up 70%! We discuss this in detail in our book The Neglected Sun. In the ozone layer and the ionosphere UV light is converted into warmth and this leads to correspondingly significant temperature changes in the range of several degrees. This warm-up and the increased formation of ozone leads to interrelated mechanisms and changes in circulation in the atmosphere.
Based on ice cores Matthes and Thieblemont could show evidence that years with harsh winters over the northern hemisphere were related to low solar activity (Adolphi et al. 2014). One example are the strong winters that gripped Northern Europe and North America from 2008 to 2010. During those years we found ourselves in a solar minimum.
And when one looks at the development of cosmic radiation since 1984, an increasingly strengthening magnetic field from solar cycle no. 20 (1964-1976) to cycle no. 22 can be seen along with a weakening of cosmic radiation. A reversal of the effect can be seen since solar cycle number 23. Just how large the UV effect or the fluctuating solar magnetic field are on climate is not possible to say at this time. However in the past there is good agreement between the warming phases and high levels of solar activity. The assumption that only CO2 by itself determines the temperature development in this century is in any case very shaky.
Figure 3: Neutron monitor Oulu (Finland) as a measure for cosmic radiation