SIR – Councillor Roger Taylor is right (T&A, January 18) – climate has changed many times over billions of years, mainly without the help of mankind. Until now.

CO2 is not the only forcing agent, and just complements the influence of an increasingly-hotter sun, cyclical changes in the Earth’s orbit around it, tilt towards it, and the way the axis wobbles.

Add the reflectivity from different surfaces, the albedo, and greenhouse gases to this and the climate will change.

Fifteen-thousand years ago, the Ice Age ended as the temperature had warmed because changes in the orbit produced more solar radiation in the northern hemisphere summer, so the ice began to melt.

The darker uncovered land and sea absorbed more heat, so it became warmer and more ice melted.

As CO2 is less soluble in warmer water, it outgassed from its dissolved state and began to act as an amplifying greenhouse gas, and the result is the present interglacial period that we now threaten with even more CO2.

Keith Thomson, Heights Lane, Bradford