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Wednesday, June 5, 2024 | Back issues
Courthouse News Service Courthouse News Service

Great Lakes saw record low ice coverage in 2023-24

Less ice coverage on the lakes could lead to increased coastline erosion, more severe winter weather and greater disruptions to local ecosystems.

CHICAGO (CN) — Ice coverage on the Great Lakes hit record lows this past winter, researchers with the National Oceanic and Atmospheric Administration's Great Lakes Environmental Research Laboratory have announced.

Between late November and late April, ice covered only 4.3% of the lakes' surfaces on average. That's the lowest figure recorded since scientists began tracking Great Lakes ice levels in 1973. Taken individually, Lakes Superior, Michigan, and Huron also saw record low averages; none of them experienced ice coverage averaging above 8%.

"The northernmost regions of Lake Superior often have lake ice throughout April, even during particularly mild winters like 2023-2024," Great Lakes Environmental Research Laboratory spokesperson Gabrielle Farina said in a summary of the laboratory's findings. "This year, Great Lakes ice cover officially hit 0.0% on April 20th."

The annual maximum extent of ice coverage on the lakes was also near record-low levels, reaching 16% in January. Only three years — 1998, 2002 and 2012 — saw lower maximum ice cover.

News of the record low ice levels comes amid other disturbing climate figures. This week NOAA declared April 2024 the hottest April it had ever seen, continuing the 11-month trend of each month since June 2023 being the hottest respective month on record. The administration also predicted this week that 2024 had a 61% chance of being the hottest year ever recorded, with absolute certainty that it would at least rank in the top five.

For the Great Lakes region specifically, the reduced surface ice levels could have profound impacts on local weather, ecology and even geography.

"The extent of ice coverage, especially near the shore, acts as a buffer to coastline erosion," Illinois State Climatologist Trent Ford said in an interview Friday.

Without that buffer, shorelines are at increased danger of collapsing into the lakes, Ford said. In recent years, shoreline erosion has affected communities in all U.S. Great Lakes states and in Ontario, Canada. Less ice to protect the coasts against waves and winter weather means the erosion will likely continue apace.

"Communities on the coast... sort of rely on those winter buffers," Ford said.

Lake water cools more slowly than air in the cold months, so less ice also means more heat energy to drive that severe weather.

"The lakes, even fairly deep into winter, act as an energy reservoir for the atmosphere," Ford said. "Having less ice cover means a greater reservoir of energy for lake effect snow."

More winter storms and lake effect snow means more stress on lakeside communities' infrastructure, especially if the effect is compounded over years.

"My concern is not so much having one-off hot years, but if we string many of these years together," Ford said.

Strings of years with little lake ice could become increasingly common in the future, Ford explained, as each year that sees reduced ice coverage decreases the likelihood of ice forming the following year. Water that is already relatively warm and iceless when spring starts will only get hotter over the summer, and stay warmer longer into the fall and winter — making it more difficult for the lakes' surfaces to freeze.

It's a feedback loop scientists have also noted in the Arctic and Antarctic, where as of April average sea ice extent is trending below that observed in prior decades.

"Both hemispheres are well below the 1981 to 2010 reference period average, but neither are near record-low extents," the National Snow & Ice Data Center reported earlier this month.

Warmer, less icy lakes could impact local ecosystems, both on land and in the lakes themselves. The Environmental Law and Policy Center, an environmental advocacy think tank, concluded in a 2019 climate change impact assessment that higher temperatures in the lakes have already increased bacteria levels. The increased air and water temperatures also facilitate the spread of invasive species that prefer warmer conditions. Already, moose populations in the northern stretches of the region have declined, while white-tailed deer continue to move north into traditional moose territory.

"More than 3,500 species of plants and animals use [the Great Lakes Basin's] large network of streams, lakes, inland wetlands, coastal marshes and forests," the Environmental Law and Policy Center wrote in its report. "Many of these species are rare or are found nowhere else."

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Categories / Environment, Science, Weather

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