Will global warming raise water levels in Lake Michigan like it will in the oceans?
— Mick Bulakowski, Palatine
No. The level of Lake Michigan will not increase because the lake is not a final repository of water. Water enters Lake Michigan from rivers, precipitation, movement of groundwater and condensation onto the lake surface from the air (mainly in the summer). It exits the Lake Michigan/Huron system through the St. Clair River. (Lakes Michigan and Huron are actually a single lake, connected by the Straits of Mackinac.) Evaporation from the lake surface, mainly during the winter, also accounts for water loss.
Only the level of the world ocean is affected by global warming because only it is the final repository of water. Melting of land-based ice and snow and an increase in the volume of ocean water due to warming are responsible for rises in the ocean level.
Global warming will not raise water levels on Lake Michigan.