First, there is doubt about the extent and f this warming. Initial evidence comes from weather stations. However, most of these are in cities, which are warmer than rural areas nis explains much of the increase in average temperature. Even if we acknowledge that the world has warmed, this warming is probably part of a natural cycle. The earth naturally warms and cools. At the time of the dinosaurs it was warmer than today, during the last ice age, it was much cooler. In addition, the rise in temperature over the last 200 years has not been constant. Average temperatures fell during the period from 1940 to 1970. If warming is caused by CO2, how can we explain this? On top of that, although there does appear to be a link between