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Project October 4, 2023

Climate Change in the Great Lakes May Be Causing History To Repeat Itself


Karen Alofs became an ecologist to study things she could see in the environment around her—and what Alofs is seeing is history repeating itself.

Alofs specializes in freshwater fish, and she was interested in if fish were moving north as man-made climate change caused the temperatures of the Great Lakes to warm. She’s found the answer buried in the past.

Fish first colonized the Great Lakes 14,000 years ago at the end of the last ice age, moving from what is now the Atlantic seaboard and the Mississippi Valley through rivers and streams that no longer exist into the ecologically empty Great Lakes. Once there, they thrived in the open habitat and on unexploited food sources.

Now, Alofs’ research shows the same processes that fish used to colonize the Great Lakes are allowing them to invade waters to the north. Climate change has warmed rivers and streams that were once too cold for these fish. However, instead of finding open waters with plentiful food, Alof’s research shows, these new arrivals are moving into a fragmented environment degraded by habitat loss, out-competing and displacing the species already there and upsetting an already fragile ecosystem.


A woman walks along a dock with a boat nearby


Connected Coastlines

Connected Coastlines


yellow halftone illustration of an elephant


Environment and Climate Change

Environment and Climate Change