paleoWeather: CESM-HR simulations with water isotopes for the Last Glacial Maximum

Supported by an Accelerated Scientific Discovery (ASD) Derecho computing grant (ACGD0008 to Otto-Bliesner; paleo-Weather), high-resolution Community Earth System Model (CESM-HR) simulation of the Last Glacial Maximum (LGM, 21 thousand years ago) has been completed. The high-resolution simulation includes water isotope capability, enabling direct comparisons with isotope records of past and present climate change from a range of archives. The simulation followed the protocols of the Paleo-climate Model Intercomparison Project phase 4 (PMIP4) and was run with atmospheric CO2 concentrations of 190 ppmv and ice-sheet conditions from the ICE-6G reconstruction. The simulation was initialized from a near-equilibrated, low-resolution companion simulation and integrated for 60 years.

The LGM dataset is one of four high-resolution simulation datasets produced through the ASD paleo-Weather project. The other datasets represent the Preindustrial, mid-Piacenzian Warm Period, and two Early Eocene Climatic Optimum. Establishing separate GDEX dataset records for each period will allow the respective leads who set up and ran the simulations to serve as leads for the corresponding DOI. Each GDEX landing page will include links to the other paleo-Weather simulations, enabling discovery and comparison across climate periods.

To our knowledge, the ASD paleo-Weather collection represents the first high-resolution paleo-climate simulation suite of this kind made available to the community. Its horizontal grid spacing is approximately ten times finer than traditional climate-model configurations, which typically use resolutions of 1 to 2 degrees. The CESM-HR resolution more realistically represents synoptic- and mesoscale atmospheric and oceanic phenomena, together with their interactions with large-scale circulation.

The LGM dataset will support research on weather/climate interactions in a cold-climate state, including studies of extreme events such as heat waves, atmospheric rivers, and tropical cyclones. More broadly, the paleo-Weather simulations complement the MESACLIP historical and future simulations, providing opportunities to investigate links between climate and weather extremes across past, present, and future climate states.