NOAA/WDS Paleoclimatology - Lake Titicaca 60 kyr Leaf Wax Hydrogen Isotope Data

A record of the hydrogen isotopic composition of terrestrial leaf waxes (dDwax) in sediment cores from Lake Titicaca provides new insight into the precipitation history of the Central Andes and controls of South American Summer Monsoon (SASM) variability since the last glacial period. Comparison of the dDwax record with a 19-kyr dD record from the nearby Illimani ice core supports the interpretation that precipitation dD is the primary control on dDwax with a lesser but significant role for local evapotranspiration and other secondary influences on dDwax. The Titicaca dDwax record confirms overall wetter conditions in the Central Andes during the last glacial period relative to a drier Holocene. During the last deglaciation, abrupt dDwax shifts correspond to millennial-scale events observed in the high-latitude North Atlantic, with dry conditions corresponding to the Bolling-Allerød and early Holocene periods and wetter conditions during late glacial and Younger Dryas intervals. We observe a trend of increasing monsoonal precipitation from the early to the late Holocene, consistent with summer insolation forcing of the SASM, but similar hydrologic variability on precessional timescales is not apparent during the last glacial period. Overall, this study demonstrates the relative importance of high-latitude versus tropical forcing as a dominant control on glacial SASM precipitation variability.