This piece appeared in the Methodist Recorder, 14 Dec 18, and is republished here by permission.
Howard Curnow, a familiar figure here, reminds us of the nature of the IPCC and the accuracy (or otherwise) of its predictions.
SOME QUESTIONS TO BE ANSWERED
I hope I may be allowed a response to some of the comments made by Jon Cooke (Recorder, 30 Nov). He says of me, "His conjecture that they (The IPCC) have a political bias is typical of the small minority of climate change deniers who, backed by the vast profits of the oil and gas industry, try to urge people that the burning of carbon fuels is not harmful and the cause of climate change".
First, I did not suggest that the IPCC had a political bias; I simply observed that it was not a purely scientific body - the simple fact that it is "intergovernmental" must mean there is a political aspect to its activities.
Next, he refers to the "small minority of climate change deniers". I take it he is referring to people more accurately described as anthropomorphic global warming (AGW) sceptics, since I know of nobody who denies that climate change exists, as it always has. The ranks of such sceptics includes a number of reputable scientists, some of whom were involved in the very first IPCC report.
Two facts, which I take to be beyond dispute, underpin the AGW theory: that carbon dioxide is a so-called greenhouse gas and that for 30-odd years from about 1970 there was quite a good correlation between the increase in carbon dioxide in the atmosphere and the increase in average global temperatures. However, as every scientist should know, a correlation between two sets of data is not proof that there is a causal relationship between the two things being measured; and the idea that from 1970 onwards climate change has been driven by increasing levels of carbon dioxide makes me want to ask two questions to which I have yet to receive convincing answers.
The first question is: if carbon dioxide is the driver of climate change, why did the 20th century see steadily increasing levels of carbon dioxide but did not see a corresponding increase in temperatures? Far from this; while temperatures were on the increase up to about 1940, they then declined between 1940 and 1970, before rising again from 1970 (and levelling off - or at least not continuing to rise ate the same rate - from the turn of the century.
Second question: many different factors have caused the climate to change over the centuries. Why does it now seem to be assumed that such factors pale into insignificance and that carbon dioxide alone is driving the climate?
Some of the prediction contained within IPCC reports rely heavily on computer models -underlying most, if not all, of these is the assumption that carbon dioxide is the driver of climate change. The fact that the range of temperature projections has proved to be higher than reality should, at the very least, lead to a questioning of the extent to which carbon dioxide is a climate driver.
I'm sorry, but if I am asked to believe that all the different factors which combined the produce the Roman and medieval warm periods and the "little ice age" suddenly ceased to have an important bearing upon the climate in 1970, I just cannot do so.
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