Extreme weather and climate change

IN a letter ‘No, the globe is not actually cooling’, Professor Bruce Webb makes some false statements. I suggest that in future he sticks to his subject of geography, and lets physicists comment on matters of physics, of which he appears to have minimal knowledge.

He states that the main greenhouse gases (gases which absorb and emit radiation in the infrared spectrum) are carbon dioxide, methane and nitrous oxide. This is false; the main greenhouse gas is water vapour, which constitutes between about 0.5 and 3% of the atmosphere, depending on location.

Even the Intergovernmental Panel on Climate Change (the IPCC) and the Royal Society state this. Carbon dioxide constitutes only about

0.04% of the atmosphere and the concentrations of methane and nitrous oxide are so low that they are measured in parts per billion.

What is more important is that carbon dioxide’s ability to absorb and emit infrared radiation is essentially saturated, so that even a doubling of its concentration would have a negligible impact on the climate. The impact on the climate of increases of carbon dioxide, methane and nitrous oxide are undetectably small. Water dominates both in terms of its concentration and its dominance of the infrared spectrum.

Prof Webb accuses Gareth Jones of confusing short-term weather effects with long-term climatic changes, and yet he does exactly the same. He seems to think that recent extreme weather events are symptomatic of climate change.

The IPCC says that there is no evidence linking extreme weather events with a warming world. Historical evidence is that extreme weather events are more frequent and more severe during periods when the world is cooler (such as during the Little Ice Age over 200 years ago).

Dr Phillip Bratby (retired physicist) Rackenford, Devon