The sun or not the sun?

I reproduce below part of a curious article from Germany's generally scholarly Max Planck Society. The author, Helmut Hornung, admits that fluctuations in solar output can impact the earth's climate but says:  "Not this time".  Recent warming is not caused by solar change.  He is right. It was caused by El Nino.

But he is not talking about the 2015/2016 El Nino period.  For an unexplained reason he cherrypicks the 2001 to 2010 period. And he says that the temperature of that period was 0.2 degrees warmer than the previous decade.  And since the sun did not change during 2001-2010, the sun could not have caused that inter-decadal warming.

That sounds logical at first but the devil is in the detail. He pays no attention to the temperature fluctuations during those two periods.  There was something of a temperature step-change around 1998, when the temperature rose by about 0.2 degrees but there was no change thereafter.  The temperature just moved to a slightly higher plateau at that time. It reached a new level and stayed there.  It was NOT continuously warming during that decade.  So temperature and the sun actually mirrored one-another.  The sun did not change during 2000-2010 and nor did the temperature.  So if we look at the temperature details, they would seem to prove exactly what he wanted them to disprove.

That was the only attempt by him to prove his case. For the rest he just asserts that temperatures have gone up long term and CO2 has gone up long term.  But that proves nothing.  It is an asserted causal relationship, not a proven relationship. And it ignores the lack of a smooth relationship that you would expect of a causal relationship.  Both temperatures and CO2 went up in  fits and starts but they were not the same fits and starts. The precise effects on temperature that CO2 levels are supposed to produce were not produced.

CO2 molecules don't have a little brain in them that says "I will stop reflecting heat down for a few years and then start up again". Their action (if any) is entirely passive. Yet temperature can stay plateaued for many years (e.g. 1945 to 1975) while CO2 levels climb. So there is clearly no causal link between the two. One could argue that there are one or two things -- mainly volcanoes and the Ninos -- that upset the relationship but there are not exceptions ALL the time. Most of the time a precise 1 to 1 connection should be visible. It isn't, far from it. You should be able to read one from the other. You can't.

Another oddity: He puts the increase in CO2 back to 1750: "the carbon dioxide concentration has increased by 30 percent since industrialization began in the mid-18th century." He may be right but most Warmists say 1950 or thereabouts

Interesting that he admits that the sun CAN have an influence though.  Warmists normally pooh pooh that altogether

It’s becoming warmer on Earth. Temperatures during the period spanning 2001 to 2010, for example, were around 0.2 degrees Celsius higher than the previous decade. No serious scientist doubts that humans play a decisive role here. Nevertheless, other factors also influence the global climate, for example the geometry of Earth's orbit and volcanic eruptions. But what role does the Sun play?

By way of its energy input, the Sun can directly influence the climate of our planet. However, the atmosphere only allows radiation to pass through in specific wavelengths, predominantly in visible light; the remainder is, in a manner of speaking, absorbed by molecules. Only part of the radiation therefore reaches Earth's surface and can heat it up. The irradiated surface, in turn, emits infra-red light, which is then held back by clouds or aerosols. This effect, without which the Earth would be around 32 degrees Celsius colder, warms the atmosphere. These processes resemble the conditions in a greenhouse.

To investigate the influence of the Sun on the climate, researchers look to the past. Here, they focus on the star's magnetic activity, from which the radiation intensity can be reconstructed. It is then apparent that the Sun produces more intense radiation during active periods – apparent thanks to numerous spots and flares – than during its quiescent phases.

The Sun had just such a break in activity during the second half of the 17th century, for example: between 1645 and 1715 its engine began to falter. During this period, referred to as the Maunder Minimum, Europe, North America and China recorded much colder winters. And even the summer was substantially cooler in some regions during this “Little Ice Age”. Paintings were made at the time, showing ice skaters on the frozen Thames, for example.

When looking back at the past the scientists work with both old records of observational sunspot data (beginning in 1610) and using the C14 method, which can be particularly well applied to wood, as Carbon-14 input at the ground (trees) is not constant, but also changes with solar activity. This radioactive isotope is created when what are known as cosmic rays meet an air molecule in the upper layers of Earth's atmosphere.

The solar magnetic field extends throughout the entire solar system and partially screens off cosmic rays. If the magnetic field fluctuates, so does C14 production. In this manner, the deviation between tree ring age and C14 age represents a measure of magnetic activity and consequently for the radiant power of the Sun.

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.


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