Near-record-low ice coverage on the Great Lakes this past winter

The mild winter of 2023-2024 produced the fourth-lowest maximum ice coverage on record for the Great Lakes.

Peak ice coverage for all the lakes combined was just 16 percent during a short stretch in January. The long-term average annual maximum extent is closer to 30 percent, according to the NOAA report.

The average ice coverage for the Great Lakes from early January to mid-March was just 5.3 percent, which was the lowest on record for the period.

There were a total of 15 days in February that set a new daily record low for ice coverage.

The primary reason for the lack of ice this past winter was the lack of sustained cold, due in part to climate change and a potent El Niño.

Usually, if there is a year with low ice coverage, there is an increased risk for extreme lake-effect snowfall. However, in addition to open water, you need very cold air, and that was mostly absent this past winter, thus lake-effect snowfall was below average.

What are some of the other impacts of a lack of winter ice on the Great Lakes? Ice can act as a barrier, protecting coastal communities along the lakes from big winter storms that can cause lakeshore flooding. Without the ice, there is less protection and the risk of damaging flooding is greater.

With less ice, the waters will tend to warm more quickly in the spring, increasing the risk of unusually warm water in the summer, which can promote harmful algal blooms. This can also have a negative impact on some species of fish.

Unfortunately, the future does not look very encouraging for ice coverage in the Great Lakes. Climate models show that the average, annual maximum ice coverage over the Great Lakes may decrease to 15 percent to as low as 3 percent by the end of the century depending on the lake.

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