text: In the first place, it explicitly takes no account of any future developments in bio-engineering and genetic modification, which are likely to enable farmers to plant drought-resistant crops designed to thrive at warmer temperatures, should these occur. Second, and equally important, it takes no account whatever of another effect of increased atmospheric carbon dioxide, and one which is more certain and better documented than the warming effect. Namely, the stimulus to plant growth: what the scientists call the "fertilisation effect". Over the past 30 years or so, the earth has become observably greener, and this has even affected most parts of the Sahel. It is generally agreed that a major contributor to this has been the growth in atmospheric CO2 from the burning of fossil fuels.