A model of the 4000-year paleohydrology (δ18O) record from Lake Salpetén, Guatemala

• We modeled effects of climate and vegetation change on lake water δ18O in the Maya area.
• Past shifts in vegetation cover fail to fully account for changes in lake water δ18O.
• Model results reveal late Holocene rainfall variability in the Maya Lowlands.
• Model results indicate protracted aridity between 1500 and 800 cal yr BP.
• The period of intense aridity is associated with Classic Maya cultural decline.

A simple mass-balance model provides insights into the influence of catchment vegetation changes and climate variability on the hydrologic and stable oxygen isotope (δ18O) evolution of Lake Salpetén, in the Maya Lowlands of northern Guatemala. Model simulations for the last 4000 years incorporate pollen-inferred changes in vegetation cover and account for 75% of the variance observed in the biogenic carbonate δ18O record from a long lake sediment core. Vegetation-driven hydrologic changes, however, failed to capture the full range of late Holocene sediment core δ18O variability. The model requires incorporation of additional shifts in catchment vegetation cover, inclusion of regional precipitation changes, or likely both, to explain the fluctuations observed in the lake core oxygen isotope record. Climatic interpretation of the model results suggests that there was relatively greater moisture availability between about 2400 and 1800 years ago, but increased δ18O values centered at ~ 3300, 2900, 500, and 200 calendar years before present (cal yr BP) indicate abrupt precipitation decreases. There is evidence for protracted aridity between 1500 and 800 cal yr BP.