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STANLEY FELDMAN

DOGMA

Man is destroying the planet.

IF ONE ACCEPTS that the world has become warmer over the past century and this is a threat to our way of life, then it is necessary to examine the evidence that this is due to an increase in the amount of atmospheric CO₂ produced by man.

The only compelling evidence that CO₂ is linked to the recent rise in the Earth’s temperature due to its greenhouse-gas effect comes from the studies of ice-core samples drilled in the ice caps. Although this may seem a somewhat inexact science, the picture they reveal is surprisingly reproducible. The temperatures at various depths can be measured and recorded, and the CO₂ content of the bubbles of trapped gas, while subject to a little variation, is also remarkably consistent. The dating of the samples is liable to small errors as the decay rate of the various isotopes measured can be influenced by outside events. Although these measurements cannot be considered definitive, our confidence in them is greatly enhanced because they have proved to be reproducible in different ice cores from varying sites made by different investigators. However, one should be cautious in interpreting these values as accurately reflecting the actual temperatures and CO₂ content of the atmosphere at the time the bubbles became trapped in the ice, since it is probable that some CO₂ will have leached out, over thousands of years, even into frozen ice.

The results of these investigations have been presented, in various forms, for up to 50 million years, but over 500,000 years their accuracy becomes increasingly questionable. It is the general close parallel, the casual association between the rise in temperature and the rise in CO₂ over the past 10,000 years, that has led to the present persuasion that the temperature change is driven by atmospheric CO₂. However, close examination of the samples from the Vostok Lake area of Antarctica over this period shows that in many instances the temperature increase occurred some 600 to 1000 years before the increase in CO₂.

Exactly the same association with temperature is also found when one examines the effect of the Milankovitch cycles (explained in Chapter 1). It is accepted that the periods of warm weather produced during these effects are due to the skewing of the Earth’s trajectory around the sun so that it comes to be closer to the source of the sun’s heat and is nothing to do with anthropogenic activity. It has been clearly demonstrated that, during each of the predicted Milankovitch warm spells, the CO₂ in the atmosphere increases. It is evident that a rise in CO₂ in this case is a consequence of the warming during these cycles and not the cause. We are at present coming to the end of a warm cycle that probably started at the end of the Little Ice Age some 400 years ago.

There is good evidence suggesting that the cause of some of the global warming is due to an increase in solar irradiance. There is a close correlation between solar activity and the atmospheric temperature in the Arctic between 1880 and 2000 (see Figure 4.1a). This association is much closer than that between temperature and CO₂ during the same period (see Figures 4.1a and 4.1b).

Figure 4.1a: Global warming and CO2 in the atmosphere over the past 120 years (source: W Soon)

Figure 4.1b: Global warming and sunspot activity over the past 150 years (source: W Soon)

As the rate of CO₂ production has accelerated, it has led the International Panel on Climate Change (IPCC) in 2001 to predict, using mathematical models, that, without curbing the rate of CO₂ production, Earth’s temperature will increase by between 1.4 and 4.2ºC in the next hundred years. The assumptions made in these predictions include a continuously accelerating increase in population, no adaptive responses – such as a switch to alternative energy sources – and an accelerating growth in energy demand per capita. Using their figures and the presumption that it is CO₂ that is causing climate change, the mean of the most optimistic and the most pessimistic of the reasonable forecasts by the IPCC is that we may expect a rise in temperature by the beginning of 2100 of 2.8ºC. This increase in temperature is about the same as the difference experienced between those living in London and those in the surrounding countryside and would render our climate similar to that of the South of France. Inevitably, it will be the coldest part of the day that will be most affected by this rise in temperature. The warmest days will not necessarily get much warmer. It will hardly cause the end of the world.

However, there are inherent problems in accepting the importance of the role of CO₂ in producing climate change. Apart from experiments carried out in the laboratory, the main evidence in support of the theory comes from one type of investigation – the ice-core samples. Associations of this kind between two events do not meet the criteria required for scientific proof. For there to be any confidence in the hypothesis, it is necessary to demonstrate either that lowering the CO₂ in the atmosphere produces cooling or raising it causes warming. Unfortunately, it is impossible to lower the CO₂ acutely but there is ample evidence that the world has cooled when the CO₂ in the atmosphere has been very much higher.