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Climate change

According to a study by professors at the University of Minnesota Duluth, Lake Superior may have warmed faster than its surrounding area. Summer surface temperatures in the lake appeared to have increased by about 4.5 °F (2.5 °C) between 1979 and 2007, compared with an approximately 2.7 °F (1.5 °C) increase in the surrounding average air temperature. The increase in the lake's surface temperature may be related to the decreasing ice cover. Less winter ice cover allows more solar radiation to penetrate and warm the water. If trends continue, Lake Superior, which freezes over completely once every 20 years, could routinely be ice-free by 2040 although more current data through 2021 does not support this trend.

Warmer temperatures could lead to more snow in the lake effect snow belts along the shores of the lake, especially in the Upper Peninsula of Michigan. Two recent consecutive winters (2013–2014 and 2014–2015) brought high ice coverage to the Great Lakes, and on March 6, 2014, overall ice coverage peaked at 92.5%, the second-highest in recorded history. Lake Superior's ice coverage further beat 2014's record in 2019, reaching 95% coverage.