The effect of Pacific climatology on the North American Ice Sheet at the Last Glacial Maximum

Surface ocean conditions and atmospheric dynamics can affect the surface mass balance (SMB) of remote ice sheets via their influence on heat and moisture transport. Here, we use the FAMOUS-ice coupled climate-ice sheet model, coupled to a slab ocean, to simulate the Last Glacial Maximum (LGM). The model was run hundreds of times to produce a large ensemble that captures a range of uncertain model inputs (parameter values). We investigate the range of simulated atmospheric circulation patterns in the 16 ‘best’ ensemble members based on constraints, such as global temperature, their relationship to sea surface conditions in the North Pacific and the interactions with the North American ice sheet. We present evidence of upper tropospheric planetary waves that facilitate communication between the tropical Pacific and extratropical Laurentide ice sheet region, yet there are clear differences in upper tropopsheric dynamics when compared to recent historical period. There is limited evidence for this tropical-extra-tropical relationship being directly responsible for regional differences in Laurentide SMB evolution.