Interpreting precession-driven δ18O variability in the South Asian monsoon region

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 and water-tagging capability to deconstruct the precession signal found in SASM speleothem records. Our results show that cycles of precession-eccentricity produce changes in SASM intensity that correlate with local temperature, precipitation, and delta O-18. However, neither the amount effect nor temperature differences are responsible for the majority of the SASM delta O-18 variability.