Anyway, I don’t understand what kind of an argument “the climate has changed before” is supposed to be. We have also had wars and bubonic plague and genocide before. That doesn’t mean we wouldn’t try to prevent it from happening again, does it? “Don’t worry, toothache is something completely natural. It occurs every 3 to 4 years,” said the dentist. Would you then relax and keep eating sugar and smoking cigars?
The other big difference between the past and now is that we are 7.4 billion people, many of them living in places that were uninhabitable during previous dramatic climate periods. Desertification and floods already affect large areas now and if temperatures rise further, millions of people will have to move to moderate climatic zones, where pressure on space and resources will grow.