July 16, 2025

The Impacts of Climate Change on the Great Lakes

More than a dozen leading scientists and experts from Midwestern U.S. and Canadian universities and research institutions released a report update highlighting the climate change impacts on the Great Lakes region.

In recent years, our planet has experienced some of the warmest temperatures ever recorded, record-breaking weather extremes, powerful storms, increasing tragic flooding from rising sea levels and associated storm surge, huge wildfires, and continued melting of glaciers and polar sea ice. The accelerating pattern of changes affect communities around the globe, but they are also is affecting us here at home. Climate change is causing significant and far-reaching impacts on the Great Lakes and the Great Lakes region.

In 2019, ELPC published a special assessment by leading university research scientists that examined the current and projected impacts of Climate Change on the Great Lakes and the surrounding region, drawing from an array of existing research. In this new 2025 update, the scholars are back to highlight new observations, research, and lessons learned over the past six years. They found that the 2019 assessment continues to be a sound, valid examination. Continuing to update, assess, and understand how climate change impacts the Great Lakes region is important to policymaking and advancing resilience.

Key Findings Include:

• 

  Observed Yearly Mean Temperatures are rising in the Great Lakes states of MN, WI, IL, IN, MI, OH, PA, & NY

  The Midwest is Warming: Since 1951, annual average air temperatures have increased by 2.9°F in the U.S. Great Lakes region (GLISA 2025). Moreover, since the 2019 report, the Midwest has already warmed another two-thirds as much (1.1°F) as it did in the decades before that (1.6°F), so warming is accelerating. 

• More Dangerous Heat: Urban areas like Chicago may experience over 200 hours above 95°F by the 2030s, up from just 30 hours in recent years. This spike in extreme heat increases energy costs and endangers vulnerable residents. 
• Declining Ice Cover: 2024 recorded the lowest average winter ice cover on record for the Great Lakes (only 4.3% average). Less ice disrupts ecosystems, worsens shoreline erosion, and hurts tourism and fishing economies. 
• Harmful Algal Blooms Expanding: Significant rise in industrial agricultural runoff and warming lakes are driving toxic algal blooms—even in typically pristine Lake Superior—threatening human and pets’ health, drinking water, aquatic life, the tourism economy, and recreation. 
• Economic Toll: Reduced snowfall is undermining winter sports industries, while stronger storms and flooding strain infrastructure, impede outdoor industries, and raise insurance and maintenance costs. 
• Vanishing Fish Populations: Whitefish—a staple of the Great Lakes ecosystem and economy—could disappear from parts of Lake Michigan within five years, even if commercial fishing halts. Invasive mussels and warming waters are decimating food sources and spawning conditions. 
• Tick and Disease Expansion: Invasive ticks like the Asian longhorned tick and Lone Star tick are spreading across the Midwest, increasing risks of Lyme disease and other illnesses. 
• Older Tree Growth Fosters More Carbon Sequestration: A new study of tree ring data in Northern Wisconsin offers new evidence that many varieties of older trees sequester more carbon than previously believed, strengthening the argument that forest managers so delaying harvests to allow vigorous growth also are enabling can enable higher levels of carbon sequestration. Uncut forests act as carbon sinks for atmospheric CO2 and thus play a key role in modulating greenhouse warming and climate change. 

We cannot take the vast natural resources of the Great Lakes for granted. Scientific analyses clearly show that climate change has already greatly affected the region and that these impacts will continue and expand as the pace of climate change accelerates. More than 40 million people rely on the Great Lakes for drinking water, fisheries, recreation, commerce, and industry, all of which are impacted by climate change. The lakes sustain more than 170 species of fish and habitats for over 3,500 species of plants and animals, many of which are rare or found nowhere else. People value this unique region for its ecological diversity, economic opportunity, and invaluable cultural importance. For all these reasons, we must reduce the effects of climate change on the Great Lakes.

Learn more about ELPC’s climate work here