SIR – Malcolm Wood (T&A, May 4) should know by now that global warming can’t be judged by one seasonal event. That is the weather, and climate is the average over 30 years.

If he wants to quote the coldish winter, then he should also, in fairness, point out that Tennessee had 19 inches of rainfall in two days recently, and that Australia, South Africa and South America set record high temperatures just months back. He conveniently forgets that in the northern hemisphere, last winter was the warmest on record.

Keith Thomson, Heights Lane, Bradford