The (tired) sun in September 2013 and spectral progress
By Frank Bosse and Fritz Vahrenholt
(Translated/edited by P Gosselin)
Currently solar activity is especially low. Solar sunspot number (SSN) in September was at 36.9, and thus was just 36% of the usual mean value 58 months into the cycle. The sun continues to remain in an unusually weak cycle 24, which was characterized by a 1-2 year delayed start in November 2008. The following graphic shows the mean value (blue) and the current cycle (red) and the very similar sunspot cycle SC5 (light gray) which occurred during the Dalton Minimum of the early 19th century:
Dark blue shows average sunspot cycle; red shows current cycle 24 and light gray shows SC5. Horizontal axis is the number of months after the start of cycle.
Several publications suspect that the current cycle could have a double hump. Yet there are lots of indications that a second peak already occurred in April/May 2013. It’s possible that the maximum of SC24 is already behind us and that solar activity is now trending downward. It also appears that the magnetic field of the sun has also reversed. The comparisons between the documented cycles 1-24 is as follows:
Since SC 1 (1755-1766) until today the difference between the mean value and the observed monthly sunspot number is summed up. The diagram above shows up to SC24, and it shows that no cycle has been weaker since SC7 (1828). Here the Waldmeier discontinuity correction of 1945 was accounted for.
Since the end of the Dalton-Minimum 190 years ago, never has the sun in its last 7 years been so inactive
Many people have been doing a lot of thinking about what the implications for the Earth may be. After all, the sun is practically the sole source of energy for our planet. At the top of our atmosphere it provides a gigantic 1365W/sqm. Here the solar radiation is distributed over a wide spectrum from infrared to gamma rays and we receive most of it within the visible light spectrum. And it is precisely this part that is hardly impacted by the solar activity fluctuations. The variation between a quiet sun and one of maximum activity is a mere 0.1%. That’s one reason we are still around. With more variation life on the planet very likely would not have been able develop over the 3 billion years our planet has existed.
All the frequencies within the solar radiation spectrum is what we call Total Solar Irradiance (TSI). In the past in climatology often only this magnitude was taken into consideration and the following conclusion was drawn: The sun cannot account for more than 0.1°K of temperature variation, whether it is active or inactive. This is the argument presented yet again by the latest 2013 IPCC Report. The radiative forcing is given as 0.05 watts per sqm. That is less than 2% of the anthropogenic radiative forcing (2.24 W/ m²).
But there is one massive argument against the IPCC’s view. During preindustrial times, the climate fluctuations in relationship between solar activity were observed to be much larger. Countless studies show this. Yet the IPCC obstinately sticks to its verdict that the impact of greenhouse gases has been the dominant force on climate since mankind has been adding greenhouse gases such as water vapor and CO2 into the atmosphere. In 2007 in the previous IPCC report a warming rate of 0.2°C per decade was assumed should CO2 rise at a modest rate which indeed has been the case. Using the climatically relevant period of 30 years, global temperature thus should rise 0.6°C by 2030 compared to 2000. In the latest AR5 2013 report, an increase of 0.3 to 0.7°C is forecast for the period 2016 to 2035.
So where do we stand today 13 years after the start? The observed reality has deviated markedly from the prophecies since 2006. The following diagram depicts the monthly observations as to GISS, and its departure from the postulated 0.2°C warming per decade as well as a 60-month low pass.
Where did the heat go? In the deep ocean as some are trying to tell us? In the blog of Hans von Storch (Klimazwiebel) one finds a very telling chart produced by Eduardo Zorita. It shows foremost that winter temperatures of the northern Eurasian continent contributes the most to the observed deviation:
The winter temperatures in the northern hemisphere really don’t give much back to the oceans, rather it’s the land mass between 30 and 60° latitude north! Also the thermal energy amount in the sea down to 700m in the region of the extra-tropical northern hemisphere everywhere refuses to cooperate with the climate models, and shows having reached a peak value in 2007 and since then it has gone downwards:
Chart source: Climate explorer
The extra-tropical southern hemisphere shows very little change. There the thermal energy in the oceans increased slightly. How does this fit with the theory of greenhouse gas forcing or the escape of heat to the depths of the ocean below 700 meters? Could the sun be playing a major role?
A new study very well worth reading by Ermolli et al. (2013) looks at the influence of the spectral variation of solar radiation (SSI), especially the ultraviolet spectrum: It is fluctuating much more strongly, by up to 10% between a quiet and an active sun. And at low solar activity, it generates precisely the pattern in the wintertime that we’ve been seeing since 2006: The North Atlantic Oscillation (NAO), which impacts the temperature in the Eurasian region especially in the wintertime, is controlled and effected by the UV radiation of the sun. When there is less solar activity, it gets colder in the region. This is precisely what we are observing, and the large part of the deviation observed in the pure GHG models stems precisely from that. Shouldn’t this be a wake-up call for the climate scientists to look more closely at SSI? This should have been done long ago. However, that would have meant conceding that CO2 is not everything.
The new IPCC report squandered the opportunity to produce scenarios that include the large impact of the sun, which we know always played a major role in the past. The IPCC limits the sun’s impact to the TSI only and they estimate it to be close to zero: -0.1 to +0.1°C.
However, the longer the chasm grows between climate models and reality, and the longer the projected warming fails to materialize, the more the world of science will have to acknowledge the questions of natural variability, especially UV radiation.