YOUR second leader takes the US to task for dragging their heels in reducing their production of greenhouse gases. I hear that at the CHOGM the Australians are trying to make a case for burning more of their abundant coal which would mean more carbon dioxide. That is frequently said to be a greenhouse gas that needs to be held in check. I find that very hard to follow.

According to Kaye and Laby the mass of the earth's atmosphere is just over 5 x 1018 kg and CO2 is present at about 0.03% by volume, so there are roughly 2300 billion tonnes in the atmosphere. That concentration would seem to be necessary since CO2 is an essential plant nutrient. The concentration will be higher near cities, industrial areas, and power stations, but that will have little bearing on the greenhouse effect.

Carbon dioxide is one of the very big-tonnage active chemicals of the earth. Each year about 200 billion tonnes are generated by animals breathing, decay of organic matter, volcanoes, forest fires, etc. That is roughly in balance with the amount taken up by green plants so the atmospheric content remains roughly constant.

Artificial CO2 produced by people burning fuel in fires that vary from small wood stoves, vehicle engines, up to very large power station furnaces amounts to about seven billion tonnes a year, and we can at best only save a small part of that. That small part is a drop in the bucket compared with that naturally generated. It is even less significant compared with that already in the atmosphere.

A long time ago the earth's atmosphere contained a lot more CO2 than it does now but plants fixed that and it is now locked in limestone mountains. Why don't we trust green plants to keep surplus CO2 in check now? James Lovelock's Gaia hypothesis suggests that this is happening.

If the Australians scrub the other serious pollutants out of their flue gases, releasing carbon dioxide won't do much harm.

Chris Parton,

40 Bellshill Road, Uddingston.

October 25.