J BRADLEY (HAS, June 9) asks a reasonable question when he asks why climate change came to prominence when working class people could afford a motor car in the 1960s – or was it coincidence?

Apart from misbehaviour of our sun such as the Maunder Minimum around 1645 to 1715 when the Thames froze over, the main controller of our planet’s temperature is the percentage of carbon dioxide in the atmosphere. More CO2 increases temperature as it impedes re-radiation of solar radiation to space.

This percentage is the result of absorbers, such as plants, offsetting emitters such as volcanoes and burning fossil fuels.

An observatory in Hawaii, where the global air is well mixed, has measured the CO2 percentage every few hours since 1958 and year-by-year it has risen to about 414 parts per million today. The general consensus among the scientific community (but not Donald Trump!) is that man’s activities are to blame.

Before a few hundred years ago the CO2 value was set purely by nature but since then, we’ve been burning fossil fuels at an increasing rate and the absorbers haven’t been able to keep up. Coal fires were the first large emitters and then we found petroleum!

It seems that science first woke up to this phenomenon after the Second World War and the shouting has grown louder ever since. Whether anything can realistically be done now about it remains to be seen.

So, no, the trouble didn’t just start in the 1960s when more people got cars – that was just part of the on-going problem.

Incidentally, air pollution is a completely different matter. In many ways, high altitude pollution reduces the temperature as it increases the amount of heat reflected into space before it reaches the surface – it is not a solution to the CO2 problem however!

Anthony J Foster, Peterlee