Good to see a reply that doesn’t mention governments and taxes anywhere.
Firstly let me state my personal position. I believe that human activity IS contributing to climate change. That does not mean that I necessarily believe all the predictions of the short-term consequences of climate change. I think disastrous consequences will happen but over a much longer time scale than predicted by most models. I recognise that the climate models are flawed, but perhaps not as badly flawed as some anti-climate change people would like to believe.
Secondly, there is an immense amount of bad science quoted by the anti-climate change lobby including lies, myths and misuse of carefully selected information. Mostly I attack this bad science.
Even where the science is serious it is often misused. A serious peer-reviewed paper quoting the results of some research programme may well be refuted by another peer-reviewed paper quoting the results of another research programme. People, on both sides of the argument, are highly selective in which papers they reference. For example the study by Svensmark and Friis-Christensen  suggesting that low cloud formation was influenced by solar sunspot activity through the intermediary of varying cosmic ray incidence was a serious scientific study and is frequently quoted by the anti-climate change lobby. Another serious study, Sun, B., and R. S. Bradley , which actually looks at measurements of cloud cover, in some cases over a single solar cycle and in others through several solar cycles, shows that there is no such evidence, see http://www.agu.org/pubs/crossref/2002/2 ... 0560.shtml
for a summary. I don’t see this later study being quoted?
Considering the 1,500 year cycle, I completely accept that the global climate exhibits many cycles, both short and long, and 1,500 years may well be one of them. I am not sure the evidence is as clear-cut as anti-climate change people would like to believe but I will not challenge that here. The fact that such cycles occur does not refute the possibility that there are human induced changes. Nobody, on either side of the argument, can tell you what that cycle would predict for today. Nobody, on either side of the argument, can tell you whether that cycle accounts for all the change observed today or not. The philosophy is that there is a natural cycle, the natural cycle would currently be in a warming phase and so the warming we are seeing today is wholly due to that cycle. Comforting but not very scientific is it?
Given the uncertainty of climate models, of evidence derived indirectly from various sources and lack of long-term verifiable measurements, I prefer to go back to basic physics and analyse the problem myself. To do that it is necessary to break it down into manageable chunks. I will concentrate on the question can Carbon Dioxide cause atmospheric heating?
Firstly it is an observable fact that the Earth receives most of its energy from the sun in the visible part of the spectrum. Part of this is reflected back into space, mainly by clouds and snow/ice cover. The total fraction reflected is called the albedo and for the Earth it is 0.367, a measured quantity. The rest is absorbed, i.e. about 63 %, mainly by the land and the oceans. These in turn radiate back into space but at infrared wavelengths not at visible wavelengths. If the absorbed and radiated energies are in balance then the temperature will be stable. If more is absorbed than radiated into space then the temperature will increase. If less is absorbed than is radiated then the temperature will fall. I don’t think people need a degree to understand the logic of this. The same is true of Venus. Venus is a very similar planet to Earth but is much closer to the Sun. Because of this the solar energy it receives is higher. The ratio is simply the ratio of the two distances from the Sun squared. Since the Earth is 147 Mkm from the Sun and Venus is only 108 Mkm, Venus receives 1.85 times the radiation that the Earth does. Venus also has an albedo, which is 0.65, again a measured quantity. Thus Venus only absorbs 35 % of the energy received. Taking the ratio of the two absorption coefficients and multiplying it by the ratio of the energies received gives us the ratio of the total energy Venus absorbs to the total energy Earth absorbs. This calculates to about 1.03, i.e. Venus absorbs about 3 % more energy than the Earth. Given such similar energy absorption we would expect surface temperature on Venus to be pretty similar to the Earth but it is not. Spacecraft have measured it as around 460 C. Why such a difference? Venus’ atmosphere is around 95 % Carbon Dioxide. I find this quite convincing evidence that an atmosphere with high Carbon Dioxide concentration will have a higher temperature, i.e. the greenhouse effect is real and happens on a planetary scale. OK the difference in concentration is extreme but so is the difference in temperature. The important point is that this is a simple calculation based on very basic physics and primary school mathematics. It does not rely on any complicated and potentially flawed models. It is also based on actual measurements. There are no other differences between the two planets that can account for the temperature difference.
Finally (do I hear a sigh of relief?) the carbon cycle on Earth consists of a number of carbon reservoirs and natural mechanisms that move carbon between these reservoirs. The burning of fossil fuels is a completely new, man-made mechanism that has only happened since the start of the industrial revolution. It moves geologically trapped carbon and releases it in the atmosphere, mostly in the form of Carbon Dioxide. There is no compensating mechanism to remove it. If we assume that a naturally occurring cycle repeats what it has done in the past we are adding an offset to it. Whatever temperature it reached in the past it will go higher. To make matters worse, the amount we are adding is increasing as countries like China and India move from agricultural peasant societies to industrial ones. Africa would dearly like to follow.
But lets not be miserable. Lets look on the bright side. There is plenty of evidence that we are close to or have even passed the Hubbard Peak on a global scale. The likely consequence of that is a global energy war at some point before global warming really gets out of hand. That should significantly reduce the Earth’s population and hence energy demand. So it’s not all doom and gloom is it?
PS Can I be the retired school teacher?