Abstract: Speleothem records from the South Asian summer monsoon (SASM) region display variability in the ratio of O-18 and O-16 (d O-18) in calcium carbonate at orbital frequencies. The dominant mode of variability in many of these records reflects cycles of precession. There are several potential explanations for why SASM speleothem records show a strong precession signal, including changes in temperature, precipitation, and circulation. Here we use an Earth system model with water isotope tracers an…