Re-evaluation of Climate Change in Lowland Central America During the Last Glacial Maximum Using New Sediment Cores from Lake Petén Itzá, Guatemala

Glaciological data derived from moraines, and multiproxy data from lake sediment cores (e.g. fossil pollen, diatoms, and isotope data) indicate cooling in the Central American tropics during the last ice age. Contrary to prior inferences, however, new lake core data from Lake Petén Itzá, lowland Guatemala, indicate that climate was not particularly dry on the Yucatan Peninsula during the last glacial maximum (LGM) chronozone, around 23,000–19,000 cal. yr BP. We present pollen and lithologic data from Lake Petén Itzá and an improved chronology for climate changes in lowland Central America over the last 25,000 years. The driest period of the last glaciation was not the LGM, but rather the deglacial period (∼18,000–11,000 cal. yr BP). Causes of climate shifts during the last glaciation are ascribed to precessional changes in insolation, the position of the Inter-Tropical Convergence Zone, and southward penetration of polar air masses