Evidence for Persistent Drought Over Mesoamerica Between 1400 and 1600 CE

The Little Ice Age (LIA) (c. 1350 to 1850 CE) was a major period of anomalously cold conditions over much of the Earth. However, strong heterogeneity of reconstructed climatic anomalies renders the spatial and temporal characterization of the LIA in the tropics an enduring gap to be filled. Here, we describe hydroclimatic variations reconstructed using a speleothem (GU-Xi-1) from the southern Yucat & aacute;n peninsula that precipitated aragonite since 1000 CE. Stable oxygen isotope ratios from GU-Xi-1 are interpreted as a proxy for past rainfall amounts, for which they allow to resolve variability on interannual time scales. The reconstructed precipitation record demonstrates drier than normal conditions between around 1400 and 1600 CE, which we term the Mesoamerican Dry Event (MDE) with an abrupt - within two decades - onset and termination. The beginning of the MDE occurred at the same time as estimates of the start of the LIA, indicating that there may be a link between the two events. The MDE is associated with surface cooling of the Intra-Americas Sea: between 1400 and 1600 CE, Caribbean sea-surface temperatures fell below the threshold required to sustain deep atmospheric convection, leading to prolonged drying in Mesoamerica.