The Great Lakes are running low on ice cover

Today’s Image of the Day from NASA Earth Observatory features the Great Lakes, which were “conspicuously free of ice” by late February of 2024.

“Owing to warmer winter weather and above-average surface water temperatures, ice cover stood at historic lows,” said NASA.

“Since satellite-based measurements began in 1973, ice coverage at its maximum winter extent exceeds, on average, 40 percent. In late February 2024, it stood at only about one-tenth of the average maximum.”

“The extent to which the lakes freeze is highly variable. In 2014, for example, coverage surpassed 80 percent. Since 1973, however, levels have been trending down.”

According to NOAA’s Great Lakes Environmental Research Laboratory (GLERL), annual maximum ice coverage on the Great Lakes has decreased by approximately five percent per decade due to warming winters.

Jia Wang, an ice climatologist at GLERL, noted that air temperatures are strongly correlated with ice cover and four patterns of climate variability influence temperature over the Great Lakes. This year, three of the four patterns exerted a strong influence, said Wang. “El Niño, the Atlantic Multidecadal Oscillation, and the Pacific Decadal Oscillation simultaneously imposed warming to the Great Lakes.”

NASA pointed out that an absence of Great Lakes ice can make shorelines and infrastructure more susceptible to damage from strong wind and waves. “It can also leave some fish species without protection from predators during spawning season.” 

“In addition, a lack of ice cover may influence water levels by allowing more evaporation to occur. However, NOAA reported no significant impact on water level as of late February; lake and air temperatures are similar, keeping evaporation rates low.”

The image was captured on February 24, 2024 by the Visible Infrared Imaging Radiometer Suite (VIIRS) sensor on the Suomi NPP satellite.

Image Credit: NASA Earth Observatory

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