Simulation of the Potential Responses of Regional Climate and Surface Processes in Western North America to a Canonical Heinrich Event

We apply a hierarchy of atmospheric and process models to assess the response in Western North America to a canonical North Atlantic Heinrich event that is characterized by lowering of the Laurentide Ice Sheet (LIS) and subsequent warming of North Atlantic sea surface temperatures (SSTs). Global responses to changes in the LIS and SSTs are simulated by the GENESIS general circulation model. Lateral boundary conditions for a high-resolution regional climate model (RegCM) that is run over Western North America are derived from the GENESIS simulations, and output from the RegCM simulations is used as input to a suit of models that we apply to investigate responses of alpine glaciers, lakes, vegetation, and coastal upwelling. The combined expression of synopticand regional-scale circulations yields spatially variable climatologies over WNA in each phase of our H2 event that reinforce, cancel, or reverse climatic patterns (e.g. temperature and precipitation) of previous phases. The response of terrestrial and marine processes is complex, and illustrates the possibility of spatially heterogeneous registration of millennial-scale climatic variations both within a particular phase and among the various phases of those variations.