As warm spring weather approaches, an icy Lake Erie usually thaws.
This year, that isn’t happening. The lake doesn’t have to thaw. It’s not frozen.
Ice on the lake melted entirely in mid-February, the time of year when ice cover is typically at its peak.
And Lake Erie isn’t alone.
James Kessler, a physical scientist with the National Oceanic and Atmospheric Administration’s Great Lakes Environmental Research Lab, said a quarter of the five lakes are usually frozen in mid-March.
This spring, just 6 percent of their area is ice-covered.
“It’s not a record low,” he said, “but certainly, certainly below average.”
This year’s low ice cover doesn’t surprise Kessler.
It fits into a trend of declining ice cover that’s been happening since the National Oceanic and Atmospheric Administration started tracking data 50 years ago.
Some years during that time frame have been icy. In 1979, the Great Lakes were almost entirely frozen over.
In other years, ice was scarce.
But the overall trend is clear: the Great Lakes are not freezing as much as they used to.
Kessler said lake ice has declined by about 5 percent each decade since monitoring began.
“It’s not random chance,” he said. “There is a negative trend.”
That negative trend can largely be attributed to warming air temperatures.
This January, for example, the average temperature in the continental U.S. was 35 degrees Fahrenheit. That’s the seventh warmest January on record.
Those warming temperatures have consequences.
What are the effects of declining ice cover?
As ice cover on Lake Erie gradually declines, communities along the shore are increasingly susceptible to severe weather, like strong winter storms.
That’s because ice cover prevents water from the lakes from quickly evaporating.
“So, you’re not going to get much lake effect snow,” Kessler said. “On the other hand, if a lake has very low ice cover, then there's the chance for lake effect snow.”
Ice cover also protects the shoreline from high waves, which cause erosion and can lead to flooding.
Then, there’s the impact ice has on plants and animals.
Kessler said micro-organisms which live in the lake depend on ice cover in the winter for protection from storms and waves.
“When there's low ice cover, these species have a harder time establishing themselves,” he said. “And a lot of them are the basis for the food web, so it has implications for larger species and fish that we eat.”
Additionally, because low ice cover leads to more extreme rain and snow events, it can lead to more agricultural run-off spilling into water bodies like Lake Erie.
That can increase the likelihood of toxic algae blooms, which consume oxygen and block sunlight from other underwater plants.
What will happen in the future?
So can we expect Lake Erie to have even less ice cover next year?
Kessler said it’s not that simple.
“Due to the year-to-year variability, you don't have to go back very far to find these high ice years,” he said.
Just four years ago, in 2019, more than 80 percent of the Great Lakes was covered in ice.
“If you think about it, that’s four-fifths of the way frozen,” Kessler said.
Because climate change leads to more extreme variations in weather from year to year, predicting which years will have lots of ice and which years will have none isn’t easy.
So, scientists don’t know what will happen to the Great Lakes next winter.
But if the current trend continues, they have a good idea about what’s in store for the next decade – and that’s even less ice than this year.
