Controls on the oxygen isotopic composition of precipitation in Greenland and the Arctic during climate change, a modelling perspective

Increasingly earth system models are providing insight into past climate and the relationship of proxy tracers to climate. Results from several experiments from GISS ModelE-R, a fully coupled atmosphere-ocean general circulation model, where water isotopes are incorporated throughout the hydrologic cycle are presented. During abrupt climate change events, such as the 8.2 kyr event, and other larger freshwater perturbations, ensemble simulations suggest a freshwater catalyst is consistent with δ18Oice records in Greenland. The freshwater causes diminished ocean heat transport which alters sea surface temperatures; these surface changes cause enhanced atmospheric heat transport and other related feedbacks in the climate system. All these effects impact the climate and ultimately the oxygen isotope signal across the Arctic and in Greenland. During other types of climate change, such as the mid-Holocene when orbital forcing was different from today, simulated relationships between δ18O and climate (salinity, temperature, precipitation) are also different suggesting large scale, hydrologic cycle changes have the potential to impact the δ18O at longer time scales. Interestingly, climate to δ18O relationships during these millennial climate changes are different than those at decadal time scales.