HOLOCENE TEMPERATURE AND HYDROLOGIC VARIABILITY IN THE CATSKILL MOUNTAINS: ALKENONE AND LEAF WAX RECORDS FROM PERCH LAKE, ANDES, NY

The Catskill Mountains are a dissected plateau in southern New York marking the northeastern boundary of the Allegheny Plateau, and contain reservoirs that provide water to over 10 million people in the greater New York City region. The 20th century was characterized by abundant rainfall in the Catskills, but tree ring research suggests that the region has experienced much greater hydroclimate variability than is captured in the instrumental record, including prolonged drought conditions. Documenting the full range of climate variability in the Catskills is important to anticipate possible future climate changes. Here we report a quantitative temperature reconstruction based on lacustrine alkenone paleothermometry (U^K₃₇) and a leaf wax-based reconstruction of hydrogen isotopes (∂²H) in precipitation from Perch Lake (42.12° N, 74.80° W), Andes, NY. The U^K₃₇-inferred summer lake water temperature record spans the latest deglacial through the middle Holocene (~12.2 to 5.4 ka BP). It documents warming at 11.3 ka BP followed by temperature variability characterized by a number of centuries-long cooling intervals, each coincident with a previously documented episode of meltwater discharge from Hudson Strait associated with early-Holocene Laurentide Ice Sheet (LIS) glacial events. The early Holocene was an interval of volatile climate variability in the greater North Atlantic region, as the melting LIS impacted ocean circulation and regional climate. The new Perch Lake temperature record helps quantify the climate response in the northeastern US to meltwater input to the Labrador Sea and will be used to assess general circulation model results from freshwater forcing experiments. ∂²H values of leaf waxes (n-alkanes) capture intervals of inferred drying during the Holocene and, together with n-alkane distributions and macrofossil analyses, can be used to infer hydroclimate variability, ecosystem changes, and changes in atmospheric dynamics over the Catskill Mountains during the past ~14 ka.