[Hippikos]

About CO2, here´s another interesting article about examing ice cores that put things like levels of ppm in some other perspective:

Remarkably, levels of CO2 in the atmosphere over this 400,000 year period showed an almost identical rise and fall to the changes in temperature. This poses an interesting question. Did the level of CO2 in the atmosphere cause the temperature to rise, or was it the other way about?

One reason for believing the latter is the solubility of CO2 in water, as the domestic soda syphon demonstrates. The sea contains massive amounts of dissolved CO2 - over 1000 billion tonnes of it are dissolved in the surface water alone, according to UNEP estimates. But like most gases CO2 dissolves most easily in cold water. So if the sea warmed up one would expect CO2 to be given off. This could be a possible reason for the correlation between
temperature and CO2 level found in the ice cores.

Thirdly, the cores show that past CO2 concentrations have varied between 180 parts per million (ppm) in the ice-ages and 280 ppm in warmer times. Contrast this with the level in today's atmosphere of 358 ppm. On the basis of the ice core evidence this would suggest a temperature level some 8 degrees hotter than at present - a level which may indeed correlate with some locally observed phenomena in the Arctic.

What has caused this rise in the CO2 level from 280 ppm to 358ppm - an increase that has taken place at an accelerating pace over the past 100 years? The widely held answer is human activities; principally burning fossil fuels, which send 7 billion tonnes of CO2 into the atmosphere each year. This may seem a staggeringly large figure but the climate world is full of even bigger numbers. According to UNEP, the 7 billion tonnes of human-made CO2 pales into insignificance beside the 150 billion tonnes entering the atmosphere each year as a result of natural causes such as decay of vegetation, and the 750 billion tonnes already there. Most of this CO2 is, of course, absorbed by terrestrial and marine plants leaving an annual atmospheric increase of just 3.5 billion tonnes, or about 1.7 ppm.

Whether or not it is the prime cause of global warming, increasing concentrations of CO2 in the atmosphere will certainly make the situation worse. This was the reason for the Kyoyo Protocol now being discussed in the Hague which commits governments to reducing their CO2 emissions. In looking for ways to implement the Protocol governments are focussing to some extent not just on fossil fuel burning but on the process of natural absorption as well. After all, even if we were never to burn another lump of coal or to drive another mile that would only save some 5 billion tonnes per year: even if fully implemented, the Kyoto Protocol, which calls for stabilisation of emissions at the 1990 level, would deliver only a small part of this.