Great Lakes Ice Coverage is Shrinking

KEY CONCEPTS

• While there is significant year-to-year variability in ice coverage, trends show that annual maximum ice coverage on each of the Great Lakes has declined over time. Across all the Great Lakes, the annual maximum ice cover is, on average, 22% lower than it was a half-century ago. Furthermore, ice coverage is becoming less reliable, with more frequent years of extremely low ice coverage (like this year).

• The decline in lake ice coverage is driven by warming air and water temperatures due to climate change. The lake ice season is also contracting in many cases, with lakes now tending to freeze over later and thaw out sooner. 

• Not only are they vital sources of drinking water and irrigation for the country as a whole, cultural and recreational practices connected to the lakes and lake ice are deeply rooted in the surrounding communities. From ice fishing to skating, traditional ceremonial practice and the use of ice roads, the endurance of a rich variety of historical and cultural connections with Great Lakes ice is at risk of slipping through our fingers as a result of climate change.

Ice cover is currently below average on all of the Great Lakes. While there is significant year-to-year variability in ice coverage, trends show that annual maximum ice coverage on each of the Great Lakes has declined over time. Across all the Great Lakes, the annual maximum ice cover is, on average, 22% lower than it was a half-century ago. Furthermore, ice coverage is becoming less reliable, with more frequent years of extremely low ice coverage (like this year). The decline in lake ice coverage is driven by warming air and water temperatures due to climate change. The lake ice season is also contracting in many cases, with lakes now tending to freeze over later and thaw out sooner. Based on a new method for projecting ice cover, the NOAA Great Lakes Environmental Research Laboratory (GLERL) projects a maximum Great Lakes ice cover of 30% for this season, compared to the 53% average from 1973-2020.

Winter is the fastest warming season across much of the U.S but particularly in the Northeast and Great Lakes regions, where average winter temperatures have warmed by as much as 5℉ over the past half century. Warming can be difficult for us to perceive during the cold months, especially as it can, seemingly paradoxically, can contribute to more lake effect snow in some areas. Similarly, there are important potential impacts of reduced ice coverage on the lake ecosystem that are easy to overlook, such as lower water levels, warmer waters and increased sunlight penetration, which can in turn influence water quality and challenge the survival of native fish populations.

According to NOAA, the Great Lakes hold 90% of the freshwater in the United States, and 20% of the world’s supply. Not only are they vital sources of drinking water and irrigation for the country as a whole, cultural and recreational practices connected to the lakes and lake ice are deeply rooted in the surrounding communities. 

Great Lakes fishing contributed $2.2 billion to the U.S. economy in 2016, representing over 11 million fishing trips. Among these are ice fishing trips—a traditional, cultural practice originating among indigenous communities and popular among modern recreational anglers. In recent years, finding adequate ice cover and thickness has made the activity difficult and highly dangerous. The endurance of other historical and cultural connections with Great Lakes ice, such as ceremonial practices, ice skating and the use of ice roads, is at risk of slipping through our fingers as our climate only continues to warm.

Earthrise Media Imagery

Satellite data and imagery of the Great Lakes from Earthrise Media show the contrast between a year with typical ice cover (Lake Erie 2019 vs. 2021 at right) and this year. Earthrise Media is a technology-led creative agency that builds digital experiences to show environmental change. Imagery produced by Earthrise Media from NASA MODIS of all the lakes here.

LMA Covering Climate Collaborative

The Local Media Association (LMA) recently announced their ‘Covering Climate Collaborative’, in partnership with leaders in journalism and climate science, including Climate Matters in the Newsroom. Local newsrooms who are committed to covering climate change are invited to apply for one of 25 media partner openings through February 28th. You can learn more about the project and register to attend the informational webinar on Thursday, February 4th.

POTENTIAL LOCAL STORY ANGLES

Is climate change affecting fishing and other outdoor recreation in my area?
You can refer to the 2016 National Report of Fishing, Hunting and Wildlife-Associated Recreation for more information and statistics about the fishing and hunting recreation in the United States. The U.S. Fish and Wildlife service also provides a primer on the topic, including relevant tools and resources, and the USDA Climate Hubs details potential management practices. Reach out to local recreational organizations to learn more about how they perceive the effects of climate change in their activities.

How is climate change impacting winter activities near you?
You can contact the U.S. Ice Fishing Association (USIFA) for more information about their tournaments held across the northern United States. For information on climate change and the snow sports industry, check out Climate Central’s On Thin Ice report, Protect Our Winters website, or this Climate and Skiing report from NOAA. For more region specific data, the National Ski Areas Association (NSAA) has a list of different industry statistics to analyze.

LOCAL EXPERTS 

The SciLine service, 500 Women Scientists or the press offices of local universities may be able to connect you with local scientists who have expertise on climate-related disasters in your area. The American Association of State Climatologists is a professional scientific organization composed of all 50 state climatologists. 

NATIONAL EXPERTS 

• James Kessler, Physical Scientist, NOAA Great Lakes Environmental Research Lab
  Ann Arbor, MI 48108
  (734) 224-8287
  Expertise: Great Lakes ice cover statistics, hydrodynamic+ice modelling, coastal-coupling of numerical models

• Dr. Catherine O’Reilly, Professor, Department of Geography, Geology, and the Environment at Illinois State University
  (914) 475-7893
  oreilly@ilstu.edu
  Expertise: climate change impacts on lakes, lake ice cover, water quality, lake ecosystems.

• John Magnuson, Professor Emeritus, Department of Integrative Biology and the Center for Limnology at the University of Wisconsin-Madison.
  john.magnuson@wisc.edu
  (608) 233-2036
  Expertise: ecology of lake ecosystems, lake ice cover decline, fisheries ecology.

METHODOLOGY

Data on observations of annual maximum ice coverage for each of the Great Lakes was obtained from NOAA’s Great Lakes Environmental Research Laboratory (GLERL).