Enhancing Coastal Climate Resilience with Advanced Projections: High-Resolution 3D Modeling of the Great Lakes Thermal Structure for the 21st Century

The North American Great Lakes - Superior, Michigan, Huron, Erie, and Ontario - rank within the world’s 15 largest freshwater lakes in terms of both surface area and volume. With approximately 38 million inhabitants residing within its expansive 520,000 km² drainage basin, the Great Lakes also support one of the largest regional economies in the world. The Great Lakes, however, have been a hotspot for climate change in the last few decades with the lakes warming disproportionately faster than the overlying air under climate change. Such warming has led to expanding surface heatwaves, diminishing ice cover, increasing lake-effect snowfall, disappearance of crucial ice roads, redistribution of fish habitat, and promotion of harmful algal blooms. Therefore, the evolution and projection of the Great Lakes and its regional climate under climate change has been identified as a top research priority by the scientific community. Our work presents a new state-of-the-art publicly accessible dataset, GLARM-Proj1, that delivers a comprehensive outlook on the future of the Great Lakes under climate change. It is a high-resolution daily climate dataset that was developed by dynamically downscaling Coupled Model Intercomparison Project Phase 5 (CMIP5) Global Climate Models (GCMs) using the Great Lakes Atmosphere-Regional Model (GLARM), which is a state-of-the-art regional climate modeling system that simulates the Great Lakes using a two-way coupled three-dimensional (3D) hydrodynamic lake and ice model based on the Finite Volume Community Ocean Model (FVCOM). GLARM-Proj1 spans from 1981 to 2099 and considers two future emission scenarios, Representative Concentration Pathway (RCP) 4.5 and 8.5. The Great Lakes in GLARM are simulated at a 1-4 km horizontal and a <5 m vertical resolution through FVCOM, and GLARM-Proj1 provides a 3D field of daily water temperature and a two-dimensional (2D) field of daily ice cover. A 2D field of 2-meter air temperature is also provided in GLARM-Proj1 at an 18 km horizontal resolution over the entire Great Lakes basin. GLARM-Proj1 serves as a crucial asset for the climate resilience research and planning in the Great Lakes region with the new Center for Climate-driven Hazard Adaptation, Resilience, and Mitigation (C-CHARM) already leveraging GLARM-Proj1 to address the challenges posed by climate-related hazards and low resilience in the Western Upper Peninsula of Michigan.