Madam, – The letter from Fr Seán McDonagh (February 2nd) criticising the Late Late Show’s decision to allow David Bellamy to air his views on climate change needs further comment.
In spite of the huge publicity given to the prevalent theory that recent global warming is due to higher levels of greenhouse gases in the atmosphere, there are many scientists who continue to question this belief.
Even the 2007 report of the International Panel on Climate Change leaves some room for doubt. On page 10, it states that “most of the observed increase in global average temperatures since the mid-20th century is very likely due to the observed increase in anthropogenic greenhouse gas concentrations.” Note: it says “most”, not all, and it qualifies its statement with “very likely”. On a following page, the IPCC gives a quantitative estimate of the confidence level it places on the term “very likely” as 90 per cent.
In scientific terms this is a low level of confidence; normally scientists and statisticians require a confidence level of at least 95 per cent and preferably 99 per cent before a connection is considered established. On this basis, the authors of the IPCC report, as reasonable scientists, concede a degree of scepticism about their own conclusions. A part of this uncertainty most likely derives from the inadequacy of computer models.
In general, the models which include the increasing greenhouse gas levels can fit the observed data for the past century quite well. However, the models make a much poorer job of fitting the natural (non-human) component of climate variability and the reason for this is quite evident: we do not currently understand the physical mechanisms of natural climate change or the many feedbacks involved. As a result, the relevant physics cannot be included in the models. This is important as, without a clear understanding of the natural background climate variability, we cannot be sure what might have happened had man not interfered. This is a fundamental weakness of the IPCC position.
So, if the enhanced greenhouse theory is only part of the story, what do we do? Many governments have accepted the precautionary principle (that is to adopt the IPCC’s position, in case it is later proved correct). This is a reasonable approach in the circumstances but it should not hide the fact that there are still many uncertainties in our understanding of climate change.
We need to keep the overall position in view but still give the sceptics a forum to air their views. As has so often been the case in the past, it is the sceptics (Darwin was one) who will identify the flaws in current scientific dogma. – Yours, etc,