SIR – Mr Parker (Letters, May 5) does not seem able to remember what he wrote in his first letter re aeroplane pollution.

This was written in the present tense as if it were something that is happening now (Quote ‘planes that continually fly’). In his second letter it has become an ‘intention’, ie it is hypothetical.

He also stated that you don’t see (long chemtrails) from passenger jets. As your photograph shows, we are all familiar with vapour trails, so, discounting little green men, that leaves only military aircraft. The truth is that most of his letter was nonsense.

Many schemes for countering global warming have been proposed. However, few, if any, will prove to be technically or financially viable (20 million tonnes of aluminium!). In any case, why do anything if, as he claims, global warming is mythical?

Mr Parker really should take more care in writing about ‘imagineering’ as if it is established practice.

Ron Harding, Beck Houses, Bingley