How significant has climate been in the fall of civilizations in the past? Traditional historians and archaeologists have hardly greeted climate historians with open arms. Those reconstructing the fate of ancient civilization already have to deal with a full plate of competing factors that could bring down a civilization without having to consider one such as climate. An archaeologist who has been studying a matrix of trade relations, warfare, internal strife, and political intrigue is not going to drop everything when a paleoclimatologist says, 'The weather did it.' In certain cases, however, the evidence is pretty compelling, not just in linking weather to a particular event, but also in specifying ways in which a changing climate may have undermined the legitimacy of rulers. In some cases, climate change fostered the spread of disease; in others, climate change might have set in motion a chain of events that led to migration and warfare. In one well-documented case, the cold alone made life untenable. The interplay of climate, politics, and economies is complex, but there is evidence from the past that climate change has either destroyed or at least been an accomplice in the fall of several civilizations.