17th centuries, without any anthropogenic event that would have affected the CO2. Between 1940 and 1975, there was a significant fall in recorded temperatures at a time of intense industrial activity associated with the war and post-war reconstruction. In the last decade, the Meteorological Office Hadley Centre has confirmed that satellite records show that Earth has cooled by about 0.4ºC, although the CO2 level has increased by 0.004 per cent.
Although not absolute disproof, these well-documented events throw grave doubt on the validity of the hypothesis. Until there is proven confirmation of the relationship between CO2 and the Earth’s temperature, it remains an unproven theory.
If future technical developments show there to be a fault in the analysis of the ice-core samples that have been so readily accepted as proof of the role of CO2 in global warming, then the whole scheme will be thrown into disrepute. So far, alternative methods of analysis of the age of the gases contained in the trapped bubble have supported the initial findings. The results appear to be reproducible. The problem with the ice-core investigations is that in some instances the rise in temperature found in these samples appears to precede the increase in CO2. Many of the ice-core samples from around the Vostok Lake in eastern Antarctica showed that warming actually preceded the rise in CO2, sometimes by 600 years. This effect had been noted in other ice-core samples but it is concealed by the compression of the timescale (x axis) in most presentations. Although various explanations of these findings, based on water–CO2 feedback mechanisms (the Claussius–Clapeyron equation), have been offered by the CO2 theorists, they are mathematically improbable and scientifically implausible. It remains absolutely impossible to explain how an increase in CO2 could be the cause of a rise in temperature that occurred hundreds of years earlier. This finding, if proven beyond reasonable doubt in a single site, would constitute positive disproof of the theory that the increase in temperature is the result of the rise in CO2. The rise in CO2 found after a rise in temperature can be readily explained, as any increase in the temperature of the oceans would be expected to drive off dissolved CO2. However, as they are a huge depository for energy this process occurs only slowly.
Equivocal evidence
There are many reasons why one cannot blindly accept the belief that anthropogenic CO2 is the cause of global warming without reservation. The knowledge that the Earth has cooled in the past when the CO2 levels in the atmosphere were many times higher than at present challenges the certainty with which the opinion that climate change is CO2-driven is being presented. It suggests that those who tell us that the case is proven are wrong. The evidence is at best equivocal and our approach to the theory must be more open-minded.
There is little doubt that the world has warmed up over the past 50 years and that the rate of warming is a little greater than that seen previously, even if the extent is less than that which has occurred over other periods. Although it is possible to explain the rise in temperature by cyclical changes that occur naturally, it is the rate of change that has led to the speculation that some, if not all, of this is due to the extra CO2 released by industrial activity. Certainly CO2 is a greenhouse gas but the evidence that the extra CO2 produced by industrialisation is the cause of the 0.6–0.8ºC of global warming seen over the past 100 years, or that it presages a future calamity, is insufficient to be convincing.
Evidence for and against human activity as the cause of global warming
For
• A general correlation between temperature and CO2 levels in ice-core samples going back 600 thousand years.
• An increase in human activity, CO2 levels (0.008 per cent) and temperature (0.6–0.8ºC) has occurred over the past hundred years.
• The demonstration that CO2 is a potent greenhouse gas. It is not unreasonable, therefore, to believe that more CO2 in the atmosphere will result in a reduction in the amount of the Earth’s heat that is lost into space.
Against
• The correlation between CO2 and temperature demonstrated in ice-core samples shows that in some instances the rise in temperature occurs before the increase in CO2, often by about 600 to 1000 years.
• Earth was believed to be at its coldest 600 million years ago (Snowball Earth) when the concentration of CO2 in the atmosphere was up to 100 times higher than today.
• In the past 50 years, when the measurements are most reliable, the correlation between CO2 levels and temperature is not very good. The correlation between temperature and solar activity is much better.
• There was a rise in temperature in the medieval period and a fall in the 16th and 17th centuries. Neither appears to have been associated with an abrupt change in CO2 levels. The fall in temperature between 1945 and 1970 occurred at a time of intense industrial activity.
• The changes in temperatures have not been the same all over the world, although CO2 levels in all areas are similar.
• 2007–08 has seen some unusually cold weather in various parts of the world with snow in Buenos Aires, Johannesburg, Athens and Shanghai. The coldest winter weather since 1941 was recorded in NE Australia; a very cold winter was recorded in the northeast of the USA; there was a cold spell in California in January 2008, which devastated the citrus crop.
• The CO2 released by human activity comes from the carbon sequestrated from the atmosphere many years ago. It is not newly produced, merely recycled, and has therefore not added to the net level of the CO2 on the planet.
• The amount of CO2 in the atmosphere is minute compared with the amount of water vapour and droplets. Water is a much more potent greenhouse gas than CO2.
Conclusion
It is reasonable to conclude that the world has warmed in the past hundred years and this has accelerated slightly between 1970 and 1998, after a cold spell in the 1940s and 1950s. This acceleration has now flattened off and there has been no significant warming since the El Niño peak of 1997; indeed, world temperatures have not increased since 1998. It is impossible to say whether this will remain within the limits of previous warm periods or whether it presages an exceptional period of global warming that will be a threat to mankind at some time in the future.
To say that it is proven that manmade CO2 is the cause of present global warming is wrong. The evidence is, at best, equivocal. It is an unproven theory. The approximate coincidence between atmospheric temperature and CO2 levels over many thousands of years, revealed from ice-core samples, is far from proof. A casual association falls far short of scientific evidence that is ‘beyond reasonable doubt’. Yet it is the main evidence offered in favour of the theory. Prophecies of the future trends in global temperatures have been exclusively based on computer models. These are essentially self-confirming expressions of the original input dogma.
The great French scientist, Claude Bernard (1813–78) complained of
minds bound and cramped by their own theories and despisers of their fellows… They make poor observations because they choose among the results of their experiments only what suits their objective, neglecting whatever is unrelated to it and setting aside everything which might tend toward the idea they wish to combat.
