Over the last thirty years issues of climate change have crossed the bridge between theory, history and science on one side and public awareness and international politics on the other. Can the activities of one small animal species really be affecting the chemistry of the sky and the vagaries of the weather?

The answer is that they can and are. According to recent polls, most people in Britain are concerned about climate change, although divided over what should be done about it. To many it is just too big a problem. In any case, greater warmth seems more desirable than greater cold: