Press Release

July 16, 2025

Update to Scientific Report Finds Climate Change Threatens Great Lakes

“The Great Lakes region is undergoing rapid environmental change, and the science is pointing to increasingly serious impacts in the years ahead”

CHICAGO, IL — The Environmental Law & Policy Center (ELPC) today released a major scientific update on climate change in the Great Lakes region, finding that the area is continuing its rapid rate of warming with sweeping implications for ecosystems, public health, infrastructure, and local economies.

The 2025 Update to the Assessment of Climate Change Impacts on the Great Lakes, developed by top scientists from major Midwest universities, confirms the region is already experiencing hotter summers, fewer cold nights, worsening storms, and rising lake temperatures. Left unchecked, these trends will increase public health risks, reduce fish populations, degrade water quality, and drive up energy costs across eight U.S. states and Ontario, Canada.

The updated assessment builds on a previous 80-page report released in 2019 that was commissioned pro bono by ELPC and the Chicago Council on Global Affairs (CCGA) to educate policymakers and the public about the significant changes affecting the Great Lakes, and the vital importance of taking immediate actions to protect our natural resources. More than a dozen leading scientists and experts from Midwestern U.S. and Canadian universities and research institutions conducted the 2019 report.

“The Great Lakes is where we live, work, and play. The leading Midwest university scientists who wrote this report explain how climate change is causing more real-world threats and problems in our Great Lakes,” said Howard Learner, Executive Director of the Environmental Law & Policy Center. “The scientists’ report explains how more extreme weather impacts Great Lakes water levels and shoreline infrastructure, harms ecological health, and puts constraints on outdoor recreational enjoyment and our economy.”

“This update makes clear that the projections we made in 2019 are not only on track, they’re being confirmed across many scientific fields,” said Dr. Donald Wuebbles, lead author and professor at the University of Illinois. “The Great Lakes region is undergoing rapid environmental change, and the science is pointing to increasingly serious impacts in the years ahead.”

 Key Findings Include:

• 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 evidence that older trees sequester more carbon than previously believed, so delaying harvests to allow vigorous growth 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.

Indigenous Communities on the Frontlines

The report also highlights how Indigenous peoples in the Great Lakes basin are disproportionately impacted, facing threats to cultural practices, food sources, and treaty-protected natural resources.

People of all backgrounds who live in the region believe that protection of the Great Lakes is critical, according to the Second Binational Great Lakes Basin Poll of residents in the Great Lakes basin conducted by the International Joint Commission (IJC) in 2018. In addition to IJC, other public opinion polls conducted more recently by ELPC, Healing Our Waters, and others consistently show the high value Midwesterners place on protecting and restoring the Great Lakes. It has bipartisan and indeed, nonpartisan support.

Download the Report Update:

Available online: https://elpc.org/resources/the-impacts-of-climate-change-on-the-great-lakes