MANKIND has no effect on the planet, according to Andrew Stephenson (HAS, Jan 4).

I see many effects of human activity on the planet.

You don’t need to look too hard – unless you already have blinkers on. Deforestation, pollution, overfishing, acid rain, soil erosion, water shortages, coral bleaching, mineral exhaustion and overpopulation are but a few.

If there were no humans on earth, the planet would still have it’s own many fluctuating climates, held in place by the insulating properties of the atmosphere. The insulating materials are primarily water vapour, methane and carbon dioxide. If you artificially increase the quantity of those insulating materials in the atmosphere, what do you think will happen? Will the earth heat up (overall) or cool down?

If you think it will cool down, you either don’t understand the laws of physics, or are just denying them.

The science involved isn’t that difficult to understand. If you insulate something more, it stays warmer when heated.

It’s very easy to measure the quantity of “greenhouse gases” in the atmosphere. They are rising inexorably up at the moment. How would you explain this?

The earth may have its own natural climatic variations, but where do the gases produced by humans go in a closed system? If the measured levels are going up, they certainly aren’t being absorbed, so they will contribute to the insulation effect.

If your house was on fire, would you throw oil on it, or water? Why exacerbate the problem by pouring even more insulators into the atmosphere?

I suggest you go back to school and pay more attention this time.

Dave O’Hara, Ferryhill.