Solar activity

The most challenging bit in the book I have now finished reading is at the end of the chapter on climate change. The authors suggest that the most coherent explanation therefor is 'solar activity', which I understand as follows:

1. Everything in space, including the earth is constantly bombarded with cosmic rays, which are basically protons from outer space. PS, a proton is nothing mysterious: "A proton can be thought of as a hydrogen atom that has lost its electron."

2. When cosmic rays go through the atmosphere, they turn into muons or 'heavy electrons', which in turn causes 'ionization'. Quite how a proton turns into a 'heavy electron' is lost on me, but I shall take that on faith.

3. There is a correlation between cosmic rays/muons and low-level cloud formation, ergo we can assume that the former causes the latter (remember that "High optically thin clouds tend to heat while low optically thick clouds tend to cool."). The explanation from here appears to be simply that "elevated levels of ionization seem to facilitate the coagulation of such molecules as sulfuric acid (H2SO4) in the atmosphere into tiny droplets, which then form condensation nuclei for water vapor. The condensed droplets of water then form clouds."

4. Low-level clouds tend to make the earth's surface cooler and damper, and is not good for harvests, as observed by Herschel in 1801 (who noticed the correlation between sunspots and grain prices).

5. The sun has various overlapping cycles of increasing and decreasing magnetic activity. The level of magnetic activity can be measured by the number of sunspots that can be observed. From here: "Sunspots were observed in the Far East for over 2000 years, but examined more intensely in Europe after the invention of telescopes in the 17th century. In 1647 Johannes Hevelius (1611-87) in Danzig made drawings of the movements of sunspots eastwards and gradually towards the solar equator. In 1801 William Herschel (1738-1822) attempted to correlate the annual number of sunspots to the price of grain in London. The 11-year cycle of the number of sunspots was first demonstrated by Heinrich Schwabe (1789-1875) in 1843."

6. That's all simple enough so far. What is interesting is the converse: when there are more sunspots than usual, that means that the sun's magnetic activity or 'solar radiation' is stronger, which creates a solar wind, which deflects cosmic rays from the earth, so there is less low-level cloud formation, so temperatures rise, harvests improve etc.

7. The proof of the pudding is in the eating, of course. The sun's magnetic field seems to go through lots of different overlapping cycles, the shortest is an eleven-year cycle, but there are much longer ones - so at some points in time we'll be at the bottom of one cycle but at the top of another, so they would cancel out; at other times we'd be at the top or the bottom of two or more different cycles, so they would reinforce each other. If (and that's a big IF) people are clever enough to work out these cycles, and they do indeed have the effect that is assumed (another big IF), then they should be able to forecast climate change reasonably accurately.

Glossing over the almost tongue-in-cheek retraction at the start of this article..."Typically, sunspots flare up and settle down in cycles of about 11 years. In the last 50 years, we haven't been living in typical times: 'If you look back into the sun's past, you find that we live in a period of abnormally high solar activity,' Dr. Weiss states. These hyperactive periods do not last long, 'perhaps 50 to 100 years, then you get a crash ... It's a boom-bust system, and I would expect a crash soon.'"

Excellent! Something else to worry about.