The 11 year solar magnetic cycle is associated with the natural waxing and waning of solar activity. On longer time scales, the sun has shown considerable variability, including the long Maunder Minimum when almost no sunspots were observed, the less severe Dalton Minimum, and increased sunspot activity during the last fifty years, known as the Modern Maximum. Source: Wikipedia. This figure was prepared by Robert A. Rohde and is part of the Global Warming Art project.
During the 1970s, I conducted an (unpublished) meta-analysis of data Charles Greeley Abbot collected from various sources in the early 20th Century to look for cross correlations between his solar irradiance measurements, sunspot index measurements, and weather patterns in various cities. The meta-analysis showed a significant positive correlation between solar irradiance and sunspot data, and a partial correlation between them and the temperature data.
Abbot, like nearly all astronomers and astrophysicists of his time, firmly believed in a negative correlation between sunspot index and solar irradiance, rather than the positive one his data showed. He noted the partial correlation between sunspot index and temperatures, but his prejudice about the correlation between index and irradiance led him to reject the effect as spurious.
By the end of the 1980s, the positive correlation between solar irradiance variations and sunspot index variations had been confirmed by satellite measurements, overturning astrophysicists' previous view. This allowed partial explanation of historically observed climatic variations, specifically the so-called "Little Ice Age" in the latter half of the second millennium, by reduction of solar activity observed through anomalies in the sunspot index, specifically the Sporer, Maunder, and Dalton minima. This research strongly indicates that solar variability is also an important input to the climate system that is certainly not under human control.
Now, it is becoming clear that the climate system is highly complex, with multiple positive and negative feedback loops, as well as a large number of independent forcing inputs, only a few of which are under human control (see "Aerosols Cloud Climate Picture," Science News, v. 176, n. 11., pp. 5-6 for a brief synopsis). These are characteristics of a chaotic system
Paleontologists and geologists have pieced together a fairly complete, though not necessarily detailed, picture of Earth's climate over the 4.5 billion years of the planet's existence. This picture shows a chaotic climate capable of varying over a wide temperature range. On short time scales, weather patterns are now acknowledged to be chaotic, with a horizon of predictability on the order of a week.
Taken together, these bits of information lead one to the conclusion that Earth's climate exhibits chaotic behavior on all time scales. It is, basically, a chaotic system.
Now, let's look at efforts to control climate change. We are attempting to use a chaotic system (global politics) to harness a second chaotic system (social, economic, and technical institutions) to control a third chaotic system (Earth's climate), when not all the forcing variables (e.g., solar irradiance, geology) are in our hands, anyway.
This sounds like a fool's errand.
I suggest that we could much more effectively apply our energies to developing means to react to climate change that is inevitable, than to the fool's errand of trying to direct it. Climate change, in any direction, has both positive and negative affects. It would be far better to direct our efforts toward engineering social systems, laws, and technologies to take advantage of the positive effects, and ameliorate the negative effects.
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