There is, of course, no denying that we are still at a very early stage in understanding weather. The effects of such variables as rainfall, cloud formation, the seas and oceans, gases such as methane and ozone, or even solar energy are still not really understood, and therefore the predictions about their effects cannot always be relied on. Dr. James Hansen, in 1988, was predicting that the likely effects of global warming would be a rising of world temperature which would have disastrous consequences for mankind: "a strong cause and effect relationship between the current climate and human alteration of the atmosphere". He now believes that, rather than getting hotter, our planet is getting greener as a result of the carbon dioxide increase, with the prospect of increasing vegetation in areas which in recent history have been frozen wastelands. In addition, if we look at the much reported rise in global temperature over the last century, a close analysis reveals that the lion's share of that increase, almost three quarters in total, occurred before man began to 'poison' his world with industrial processes and the accompanying greenhouse gas emissions in the second half of the twentieth century.