Climate change - the facts

At this time, with the G8 summit under way, and the media full of ill-informed nonsense about this topic, now seems like a good time to put the record straight.

Firstly, there need be no dispute that climate change is happening. We have a naturally variable climate, and it has always been so. At present, we're in a period of very gradual warming - about 0.7 deg C in the past 100 years. This is a very short period in historical terms, a mere blip in a temperature record having huge swings from prehistoric arid conditions to ice ages, and displaying all the lower order 'noise' associated with any naturally variable phenomenon. There is no reason to suppose that this blip is any more than a part of that 'noise'.

One of the many, and poorly understood control mechanisms that regulate our climate is the so-called greenhouse effect. Here, incoming solar radiation is absorbed, in certain precisely defined frequency bands, by atmospheric gases, and then re-radiated as heat. Water vapour, carbon dioxide and methane are amongst the greenhouse gases, but the chief emphasis has been on carbon dioxide (CO2), since it is emitted in large quantities, not only by natural biological processes, but also, either directly or indirectly, as a result of virtually all of mankind's domestic, commercial and industrial activities.

So if CO2 is a greenhouse gas, you may ask, the more of it we release into the atmosphere the hotter we get, right?

Wrong.

For these reasons:

• As mentioned above, the greenhouse gases only absorb energy in narrow, precisely defined frequency bands. In the case of CO2, nearly all the energy available in those bands is already being absorbed by the existing CO2 in the atmosphere - we say that these bands are near to saturation. What this means is that releasing more CO2 into the atmosphere can make very little difference to the greenhouse effect.
• In the historic record of atmospheric CO2 concentration and global average temperature, extending back over hundreds of thousands of years, CO2 and temperature can be seen tracking each other closely. Unfortunately for the proponents of the notion that mankind is causing the warming, the CO2 changes lag behind the temperature changes, and so cannot have caused them. In fact there are no examples in the records of a rise in CO2 concentration followed by a tracking rise in temperature. The conclusion is inescapable - changes in CO2 do not cause changes in temperature.

The fact is that the control mechanisms for our climate are extremely complex, and poorly understood. In the light of this, it is highly irresponsible for the scientists to encourage politicans and activists to tub-thump over climate change. Whether or not the predictions being made, and the scare stories so beloved of the media, are to be believed, the theory and the evidence simply do not support the idea that the hugely expensive and damaging changes being urged can make any difference.

Of course all this stuff is grist to the mill of the scientific establishment. The more it gets talked up and agitated about, the more disposed the research councils are to provide the juicy contracts, particularly if under pressure from politicians who see the topic as a potential vote-winner. I never thought I'd have to say this, but thank heavens for the obstinacy and pig-headedness of George W! For all the wrong reasons, the US are slowing the pace of 'action' (heaven help us) on climate change to the point where the bandwagon could run its course and be quietly forgotten, just like all the other previous armageddon fads, without any of the devastating political and fiscal changes being called for, ever actually coming to pass.