Stable water isotopes in paleoclimate simulations – results from the ECHAM5/MPI-OM and MPI-ESM model

During the past two decades, several atmospheric and oceanic general circulation models (GCMs) have been enhanced by the capability to explicitly simulate the hydrological cycle of the two stable water isotopes H218O and HDO. They have provided a wealth of understanding regarding changes of the water isotope signals in various archives under different past climate conditions. Fully coupled atmosphere-ocean GCMs with explicit water isotope diagnostics are required for a more comprehensive simulation of both past climates as well as related isotope changes in the Earth’s hydrological cycle. 

In this study, we present a compilation of latest results from our working group, based on stable water isotope simulations with a set of fully-coupled Earth system models of increasing complexity and resolution (ECHAM5/MPI-OM, MPI-ESM, AWI-ESM). Performed paleoclimate simulations follow the various PMIP protocols and include, among others, the pre-industrial, last millennial, mid-Holocene, LGM, and Last Interglacial climate. Focus of the analyses is an in-depth model-data comparison to various recent compilations of isotope records (e.g. ice cores, speleothems) and the validity of the isotopic paleothermometer on various time scales.