As promised, a reply addressing
the article Licker linked:
I see several problems with the stuff in that article. Not about the sun cycles as such, I'll take his word at face value regarding the cycle lengths and on the cosmic radiation and cloud cover variation following that.
But the following things:
- The CO2 curves he says are of doubtful significance follow the sunspot cycles even if not at the same magnitude and curve shape, especially during the 1940s. At that point CO2 concentration increase from the 1800s is up roughly 10% and then starts to gain on the other curves. No mention of the IR trapping properties of CO2 anywhere, not addressed, though an increased sunspot cycle makes sense for the rest of it.
- Related to the above, there is no consideration whether there was an El Nino phenomenon in effect during the temperature spike in the early 1900s. IIRC, there has been research into the El Nino that indicated this would have been the case. It contributed significantly to the Dust Bowl phenomenon in the US and the droughts that followed the Great Depression. No mention at all.
- He then returns to the solar cycles and cosmic radiation argument and continues as if this was the only probable cause and the solar cycle graphics he has only show the 11 year cycles, which is a geologic eyeblink. Nothing to support the stuff about the longer cycles.
- The same research to El Nino I mention above (what I remember from a BBC TV documentary, so no links, sadly
) also talks about there being fairly strong evidence of El Nino effects causing certain events in the past that affected old human civilizations, for example the droughts that destroyed Ur in Babylonia and devastated some Meso- and South American civilizations. All of these events involved significant temperature increases due to strong El Nino effects (much stronger than the early 1990s).
- The section about water vapor being the most important greenhouse gas again neglects the fact that while some amount of greenhouse gases are necessary to maintain a habitable temperature and that water vapor is by volume the greatest one, it is nowhere near as effective at trapping infrared wavelengths as CO2 is. Much like methane is 20 times more effective than CO2 as a greenhouse gas (but much shorter lived before it degrades to CO2), CO2 is more effective weight for weight. If the difference is similar, even modest CO2 increases would show increased temperatures.
- The part about temperature graphs following CO2 graphs and spiking: As temperature increases, sources of CO2 that have been unavailable become available. There is a staggering amount of methane trapped in the permafrost in Siberia and the Canadian north. As temperature rises, the permafrost melts. The methane is no longer frozen in place and is released into the atmosphere, where it shortly degrades to CO2. A cyclical repetition would see temperature rises melt existing permafrost, then glaciation causing permafrost again. This is a very plausible explanation for those portions of his graphs. I do not know what mechanisms later cause the CO2 concentration to decline, but that is not relevant here.
- The article bounces back and forth between time periods of tens of thousands and millions and even hundreds of millions of years and uses the same arguments throughout. In some sense this seems deliberately dishonest, though it could be an honest oversight. Hundreds of millions of years ago the continents were not where they are now. This means the sea currents were different as well and their different interactions could have resulted in a significantly warmer or colder period of time due to various climate mechanisms not related to CO2, so even higher concentrations could allow for ice ages. I touched on that way back in my first post, but not in as much detail, though I mentioned the effect of an equatorial warm current counteracting the cold Antarctic currents.
Those are the concerns and questions that I noticed on the first read-through and I'm certain I could get some more if I really went over it with a fine tooth comb. And that's outside my own professional field (computers) at that.
I am not saying that he is necessarily entirely wrong, but just based on that article, there are gaps in the solar radiation theory you can drive a tank division through. He makes the same mistake he accuses the CO2 crowd of making: He ignores a lot of other factors that have direct impact and then attributes the lot to his own theory. Or then that's a really dumbed down version of what he does.