Ice-cores, sediments and civilisation collapse: a cautionary tale from Lake Titicaca

The temptation to equate environmental change with archaeologically observed events is always with us, and matching a climatic downturn with civilisation collapse is perhaps more attractive then ever. The archaeologically observed collapse of the Tiwanaku civilisation in the twelfth century AD has been specifically related to a prolonged drought which would have affected the people’s ability to produce food. However, a careful scrutiny of the data from ice cores and lake sediments persuades the author that no such drought can be inferred: the evidence for climatic change is of quite a different scale and order to the archaeological changes and cannot be used as an explanation of social events.