The Great Lakes region is composed of two Canadian provinces – Ontario and Quebec; eight U.S. states – Illinois, Indiana, Michigan, Minnesota, New York, Ohio, Pennsylvania, and Wisconsin; and the watersheds, lakes, and rivers that surround the five primary lakes – Superior, Michigan, Huron, Erie, and Ontario. This includes the St. Lawrence River, which is the primary outlet to the Atlantic Ocean, and several other rivers (e.g., Chicago, Calumet, St. Marys, St. Clair, Ottawa, Detroit, Niagara) and lakes (e.g., Saint Clair, Nipigon, Champlain).

The region contains 21% of the world’s freshwater supply and 84% of North America’s surface freshwater supply.² Climate change is having and will continue to have significant effects on the freshwater resources and human communities in the region; these changes are manifesting in air and water temperatures, precipitation patterns, lake levels, and water chemistry. Direct and indirect effects of climate change will put various elements of the natural and built environments of the Great Lakes region at risk; many of these environments are already vulnerable because of non-climatic stressors, such as increased urban/suburban development, pollution, habitat degradation, and invasive species.

Practitioners need to prepare for and respond to these impacts through mitigation and adaptation measures. Mitigation refers to those efforts to reduce greenhouse gas emission reductions or enhance carbon storage; adaptation refers to those actions that aim to minimize the negative effects or exploit the potential opportunities presented by climate change. Neither mitigation nor adaptation alone will be sufficient; both approaches are needed for an integrated climate change response strategy. Practitioners in the Great Lakes region are utilizing both approaches to address climate change through capacity building, policy approaches, natural resource management actions, and planning efforts.