Orbital and internal forcing of climate on the Yucatan Peninsula for the past ca. 36 ka

A 19.6 m sedimentary sequence from Lake Quexil, Guatemala, is presented as'a'proxy record of climatic change on the low-lying Yucatan Peninsula over the last ca. 36 ka. Long-term climatic fluctuations are'attributed to orbital forcing of insolation, while abrupt changes during the late glacial period are the result of internal forcing mechanisms that remain imperfectly modelled. GCMs simulating meltwater cooling of the Gulf of Mexico may'predict some but not all climatic responses in the Circum-Caribbean. Lake Quexil did not experience greater aridity than predicted by orbital forcing during late glacial zones Q-LG 1 and 2, which were drier only in comparison with Holocene cond!tions, Q-LG 1 appears to have been colder than expected based on insolation alone, and is contemporary with the Younger Dryas event between meltwater pulses IA and lB. Thus, other feedbacks also may have cooled surface temperatures in the Gulf of Mexico, such as unique late glacial circulation pattems, increased albedo for the Florida and Yucatan Peninsulas, or surface temperatures on the North American continent. Additional terrestrial sequences are needed to improve the chronology and confirm the distribution of sub-regional climatic variability in the Circum-Caribbean.