NOAA/WDS Paleoclimatology - Lake Kail, Guatemala 6,000 Year Stable Isotope and Physical Properties Data

Long-term perspectives on past hydroclimate variability provide context for evaluating the potential future impacts of changes in Northern Hemisphere temperatures and oceanic-atmospheric circulation on the timing and distribution of precipitation in Central America. Here we use the isotopic composition of fine-grained (< 63 um), endogenic CaCO3 (d18Ocalcite and d13Ccalcite) from Lake Kail, located in the western highlands of Guatemala, to infer multi-decadal to multi-centennial-scale variability in the balance between precipitation and evaporation (P/E) over the last ~6000 years. The sediment age model is based on 210Pb and 41 14C ages, with chronological uncertainty estimated using Bayesian methods. A model that couples lake hydrology and isotope mass balance is applied to characterize the isotopic responses of lake water and calcite to changes in drought-controlling climate variables such as precipitation, temperature and relative humidity. The d18Ocalcite variations indicate intermediate-to-dry P/E conditions during the late-middle Holocene from ~6000 to ~4100 cal yr BP. There was then a shift to drier conditions at the start of the late Holocene until ~3050 cal yr BP, followed by a trend to wetter conditions until ~1500 cal yr BP. The most recent ~1500 years is characterized by high and relatively stable P/E, with particularly wet intervals from ~1500 to 1170 cal yr BP and from 470 to 260 cal yr BP. Comparisons of the Lake Kail d18Ocalcite record with Central American/circum-Caribbean proxy datasets spanning the late-middle and late Holocene indicate northern tropical hydroclimate changes were highly variable across space and time and were likely driven by regional oceanic-atmospheric responses with a secondary influence by insolation forcing.