Late Holocene Climate Change in Central Mexico and the Decline of Teotihuacan

For decades, scientists have been trying to determine the causes that led to the decline of Teotihuacan, and they have suggested several possible factors, including wars, social conflict, and droughts. The causality remains unclear, however, and interest in the topic has hardly subsided. In this study, we assess the plausibility of the drought hypothesis by exploring the drought mechanisms in late Holocene central Mexico. Our δ18O records provide valuable information regarding climate variations in late Holocene central Mexico. For example, El Nino–Southern Oscillation decoupled from the Intertropical Convergence Zone (ITCZ) mainly drove late Holocene climate, particularly between 900 and 1550 CE, causing a dry Medieval Climate Anomaly and a wet early Little Ice Age. Most interesting, our results indicate that the decline of Teotihuacan could be partially attributed to seventh-century droughts induced by a coupling of pronounced El Nino and reduced solar output (i.e., a more southern location of the ITCZ)...