An assessment of the impacts of climate change on the Great Lakes: 2025 report

This report confirms climate change is affecting the Great Lakes region through warmer and wetter weather, greater fluctuation in lake levels and disappearing fish populations. In 2019, the Environmental Law & Policy Center commissioned a study of the effects of climate change on the Great Lakes, which provide drinking water to 40 million people. In this updated report, more than a dozen scientists said the study’s findings ring true as temperatures continue to rise.

The report found average annual temperatures were 1.1 degrees Fahrenheit warmer in the Great Lakes region from 2017-24 compared to the prior four decades, and the number of days with at least 2 inches of rain or snow was 6 percent higher. Since 1951, average air temperatures have increased almost 3 degrees in the region and precipitation has gone up 15 percent. The updated assessment builds on the previous research and includes more findings that show warming at the surface and deeper waters of the lakes. Summer water temperatures on Lake Superior warmed by 4.8 degrees between 1979 and 2023. Last year, Lakes Michigan, Huron, Erie and Ontario all saw record-high average temperatures.