Mankind came late on the scene-2-3 million years ago.

Most of that time the world has been cool and human life has evolved around that .The 0 on the graph reflects a current temperature of 13/14 degrees centigrade and thus the warmest prediction for world temperature is 18/19 degrees centigrade a rise of 5 degrees.On the most optimistic forecasts there will be a rise of 2 degrees by 2100. It is the implication of a fairly rapid rise  of global temperature upon our environment and upon our lives which needs examination

Technology, intelligence and adventure have allowed men to work at the equator, at the poles or under the sea.

But for most of us, most of the time, we function best  in a fairly limited comfort zone 5-25 degrees centigrade