There’s grown up quite a cottage industry in the last few years blaming the disappearance of various ancient cultures on man-induced climate change. Since internal combustion engines were nonexistent thousands of years ago, other explanations have to be used; clear cutting of forests being the most popular. As a fad it says quite a lot about the phobias of the present day, although it says little about what actually happened in thousands of years ago.
Let it only be said that if we look solely at civilizations which have a mass of historical documentation attached to them, man-induced climate change cannot be blamed for the demise of any. However, when dealing with civilizations that we don’t know very much about (such as the Nazca) avenues are opened for all sorts of extrapolations. Von Daniken looks at the Nasca and sees evidence for extraterrestrial visitation. Why? Because that’s what he wants to see and with a convenient dearth of historical information it’s difficult to be proven wrong. When environmentalist look at the Nazca they also see what they want to see - and for much the same reason.
Spot on - all these global warmingesque theories are merely the fashion of the day.