Eurasian Holocene climate trends in transient coupled climate simulations and stable oxygen isotope records

Transient simulations of the global fully coupled climate model COSMOS under realistic varying orbital and greenhouse gas forcings are systematically compared to diatom oxygen isotope ( delta 18 O diatom) records from Russian lakes with focus on Eurasian Holocene climate trends. The measured delta 18 O diatom decrease and other temperature proxies are interpreted as large-scale cooling throughout the Holocene while the model simulations are biased too warm, likely through missing radiative forcings. This large-scale warm bias also dictates the modeled delta 18 O precipitation. Hence, at locations where the signs of model and proxy temperature/precipitation trends agree, measured delta 18 O diatom and modeled delta 18 O precipitation trends show notable accordance. An increased temporal variability of modeled delta 18 O precipitation is linked to persistent atmospheric circulation patterns. Applying the transient forcings in an accelerated way (every 10th year only) yields a similar, yet weaker or delayed model response, especially in the ocean.