Thin ice: How historically low ice coverage affects Apostle Islands, Great Lakes

Ice at the water's edge - Jeff Rennicke photo

January 10, 2024

It’s open water – not ice – as far as the eye can see. Not only in the Apostle Islands National Lakeshore but across all of the Great Lakes. As of New Year’s Day, less than 1% of Lake Superior was ice-covered – a tiny percentage but still the largest percentage of any Great Lake. Combined, ice covered roughly one-third of one percent of the surface area of all of the lakes as of the first of the year; that’s the lowest level in 50 years and the percentage is growing very slowly.

As you can see on the map from the US National Ice Center, ice on Lake Superior is now mostly confined to the bays on the northern-most edge of the lake.

Lake Superior Ice Map - US National Ice Center January 9, 2024
As of January 10th and NOAA’s Great Lakes Environmental Research Laboratory (GLERL) reports Lake Superior’s ice cover amounts to 1.29%. These numbers are still far below the historical average of around 10% coverage for this time period. One reason: December was the warmest on record for Duluth, Green Bay and the region around the lake. You can see daily ice coverage data here.


Image of open water at the mainland sea caves - WISC-Watch camera January 10th 2024
Image of open water at the mainland sea caves - WISC-Watch camera January 10th 2024

Open water at mainland sea caves – WISC-Watch photos

You can also see open water stretching to the horizon on the WISC-Watch web cameras. Ice formations are starting to build up on the sandstone cliffs above the mainland sea caves but there’s no sign of it on the lake below.

It’s been many years since the mainland ice caves near Meyers Beach were open to the public. Tens of thousands flocked to the caves in 2014. The caves have not been open in recent years because conditions have not been safe.

The National Park Service says, “Cold is super important, because obviously that makes ice. But wind is a major component as well. Due to the caves position on the northwest side of the peninsula with a lot of open water in front of them (all the way to the North Shore of MN), the right winds can wreak havoc on ice formation. In the past, we’ve seen good ice start to build up and then disappear overnight, due to a strong north wind and the waves it can create.”

Read more about what conditions it takes to open the caves to the public, on the National Park Service website.

On the chart below, you can see that ice cover on Lake Superior normally peaks in late February and early March. While a lot change in the next 3 months, we’re off to a very slow start, so far as making ice in 2024.
NOAA graph of ice cover of the years. 2024 is far below average.

The dark blue line in the lower left shows this year’s Lake Superior ice cover. The red line represents average ice cover. Source: NOAA

Below-normal ice (and snow) certainly affects winter tourism in and around the park. If you plan to hike the Lakeshore Trail above the sea caves this winter, please keep safety in mind. Depending on conditions, ice cleats, trekking poles or snowshoes may be in order. Chequamegon Bay generally ices over long before the open lake, but conditions that enable ice fishing still depend on extended cold periods. The annual Book Across the Bay race, scheduled for Saturday February 17th at Ashland, also depends on safe ice. Organizers said on January 10th that “While it’s not currently substantial for a race, with weeks to go our trail team is confident we’ll have safe ice!” Mount Ashwabay Ski and Recreation Area is starting to groom cross country trails and is making snow for downhill skiing and snowboarding on the hill. With snow in the forecast, they say “It looks like our conditions will be improving greatly.” The Madeline Island Ferry started the new year reporting “Due to the lack of ice – effective tomorrow (January 3) we will continue to run the current schedule until further notice.”

Beyond tourism, warmer winters affect the islands and their animal inhabitants. Waves driven by winter storms can cause serious shoreline erosion and damage the docks in the park. Inspecting and repairing those docks is a springtime ritual for the National Park Service. Some animals travel from island to island. They can’t when the ice isn’t there. The lack of ice cover also affects fish populations. To learn about how climate change could affect the Apostle Islands, watch a video presentation from the 50th Anniversary Resource Stewardship Symposium.

The short-term forecast does call for colder weather in mid to late January but it’s impossible to predict how this winter – and ice formation – will go. We do know that during a strong El Niño winter an unusual warming of the Pacific Ocean generally results in warmer than average winters in the midwest. And the long-term trend foretells even less lake ice in the decades ahead. The best advice for now: bundle up and make the most of what mother nature gives us.

Featured photograph: At the water’s edge by Jeff Rennicke

Jon Okerstrom
Jon Okerstrom is a Friends of the Apostle Islands National Lakeshore board member and digital and social media volunteer with a background in digital and television journalism, photography and graphic design.

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