The spawn of the devil, this CO2! Day in, day out we have scientists and politicians telling us that the very weal and woe of humanity depend on cutting emissions of it. The debates sound like disarmament negotiations or tribunals.

So CO2 is a kind of chemical weapon, is it? Yet it seems so harmless: non-toxic, colourless and almost odourless. Since one atom of carbon is combined with two atoms of oxygen with double bonds to each other, it’s a pretty stable compound. As a gas, it is distributed almost unchecked between the Earth’s mantle and the stratosphere. Nothing less than insidious. It’s evidently responsible for catastrophic damage: floods, whirlwinds, drought – it all gets laid at CO2’s disaster-ridden door. The collective term for all these atrocities is greenhouse effect. Let’s just get rid of it!

You could be forgiven for thinking this is the answer. And it’s true that the horrifying news of the disasters caused by global warming, i.e. by CO2, is not fiction. On the other hand, life could not exist on Earth if there were no CO2. It is emitted into the atmosphere by every living organism as it generates energy. When we breathe, we exhale CO2. CO2 is a natural component of the atmosphere. This and other gases ensure that the sun’s rays which are reflected by the Earth cannot all escape into space but are reflected towards the Earth again. This explains why we have an average temperature of about 15 degrees, at which life is possible, instead of around minus 18 degrees. So we owe our existence to the natural greenhouse effect.

The short-term CO2 cycle, which is completed over the annual cycle of the seasons, is one of the key natural cycles. It transports carbon, which is vital for all living organisms, between the air, water and soil. Plants absorb so much CO2 from the atmosphere via photosynthesis during their growth phase that the concentration decreases towards autumn. After that, more CO2 is discharged into the air again as the plants decompose.

There is also a long-term CO2 cycle which extends over millions of years and whose results are laid down for us in the fossil record. As man uses coal and oil as fuels, burning them, for example, for transport or heating purposes, he emits additional CO2 into the atmosphere. The more such gas there is available, the less heat from the sun radiates back into space, and the warmer the Earth becomes. Man is thus transferring CO2 from the long-term to the short-term CO2 cycle, upsetting the entire evolutionarily balanced system which ensures the mutual equilibrium of matter.
Although the surplus of CO2 also acts as a plant fertiliser, this benefit is negligible compared with the consequences of global warming such as melting poles and glaciers and the resulting rise in sea levels.

The proportion of CO2 in the atmosphere is now about one-third higher than before the Industrial Revolution of 200 years ago. CO2 emissions worldwide saw a 45 per cent rise between 1975 and 2000. This means that the problem is not CO2 in itself, but that man is producing more of it than our flexible yet sensitive climate system can cope with. The CO2 level will continue to rise, that much is certain. How much, depends on our approach to energy usage.