There is a geological maxim that the present is the key to the past, but when it comes to considering current global change, the past is the key to future. This module deals with the nature of climate change in the Quaternary period of time during which major ice ages occurred and significant evolution of the human genome occurred followed by the growth of civilizations in the post-glacial period. It focuses on the science, looking at the types of record (e.g. ice cores, marine and lake sediments, cave deposits) and the types of proxies for climate that are used. These proxies include oxygen isotopes, accumulation rates, trace elements, species present and many others. What is revealed is a rich array of information on past environments and climates and the behaviour of the climate system as a whole that we can use to inform models that predict the future path of change.