Last Glacial droughts and fire regimes in the central Mexican highlands

Abstract

ABSTRACTOver the last glacial cycle, climate variations in the Neotropics were related to diverse forcing mechanisms whose understanding has been limited because of the scarcity of continuous long records. Here we use high‐resolution charcoal particle accumulation, inorganic carbon precipitation and magnetic susceptibility data from Lake Chalco, located in high‐altitude tropical central Mexico, to assess the fire regimes and drought periods between ∼85 and 10.8k cal a BP. Overall, drought intervals were characterized by high carbonate deposition and were contemporary with high spring insolation. Most of the high fire activity periods were coupled with droughts, whereas some of them seem to have responded to volcanic activity in the basin. Periods of more fire activity during the latest part of Marine Isotope Stage 3 were associated with a long interval of higher spring insolation. Increase in drought frequency during 47–27k cal a BP were possibly linked to a more active Laurentide Ice Sheet influencing the oceanic and atmospheric controls of the tropical climatic system. In fact, Chalco and Cariaco records show similar millennial‐scale trends, suggesting a role of the Intertropical Convergence Zone in modulating moisture availability in the region.