The evidence I have presented in this book tells me the climate IS changing, that it is changing in the direction of becoming warmer, that in some parts of the world it is becoming drier, while in others it is becoming wetter. It is also evident to me that the reason the climate is changing is not because the Sun is getting hotter but because we have changed the composition of the atmosphere by adding CO2.

It is true, as geologists point out, that the Earth is accustomed to climate change. Temperatures have been far warmer than they are now; atmospheric CO2 has been far higher than it is now, though not during the past 450 000 years. In 450 000 years there is time for 450 000 generations of most insects, 200 000 generations of most animals and birds, 45 000 generations of most plants and 12 000 or so generations of people. The climate changes of those long years of successive glaciations were slow. Organisms had time to move, to remain within their comfort zones, or to evolve in order to survive.