Arthur Riley of Kalamazoo has a fond memory from Charlevoix, where he lived years ago. He said winters Up North started out snowy and gray. “But then the Lake froze,” – Lake Michigan – “And then we had a lot of sun. It was absolutely beautiful." (When the Lake freezes it cuts down on lake effect snow – more on that soon.)
Southwest Michigan is not known for its brilliant blue winter skies. And Arthur’s wondering if we might see even less sun in the future if climate change warms up Lake Michigan, and ramps up the lake effect.
“Are we going to have even more clouds and more cloudy days, more rain, more snow?”
Arthur and I asked a couple of experts. We learned global warming is having an effect on the lake and that in turn could change the weather inland. How things change in the long term depends on how warm it gets.
Warmer and wetter
Before we talk about the Lake, let’s consider how Michigan’s climate has already changed. Duane Hampton studies ground and surface water at Western Michigan University. A few years ago one of his students looked at weather records for 26 cities around the state, going back to 1970.
“What we found was that most of the cities had an increase in precipitation,” Hampton said.
These cities got more rain – but most also saw a decrease in snowfall.
“Now to try and make sense of that, more precip less snow, we also looked at the temperature signal in those 26 towns,” he added.
They found all but one had trended warmer since 1970. Hampton said the warmer the air, the more water the air can hold. So that might explain the extra rain.
“And why less snow?” he asked. “Well, it’s warmer!”
Hampton said, not only is it raining more in Michigan, we’re getting more rain all at once – in downpours like the ones that hit Kalamazoo on June 19 and 20 of 2019.
That led to floods around Kalamazoo – including at Waldo Stadium. Footage from a WOOD-TV newscast showed the turf under maybe half a foot of water, “turning it from a gridiron into a swimming pool,” as the anchor quipped.
The National Weather Service noted that June 2019 was the 11th month of unusually wet weather in Southwest Michigan.
Michigan is trending hotter and rainier. But Arthur wants to know about the Lake. How is climate change changing Lake Michigan and how that will affect our weather inland? WMU biologist Dave Karowe researches the effects of climate change. Unsurprisingly, he said the Lake is warming at least at the surface.
“Not quite as much as Lake Superior, but most of the surface of Lake Michigan has warmed detectably,” he explained. It’s warming up faster Up North than down here.
Karowe thinks there are two ways a warmer Lake could lead to more rain and snow in the region. First, Karowe says, if the water in the lake is warmer, “for sure that means that the air above the lake is warmer. So not only can the air hold more moisture, but the water of the lake has an easier time evaporating if it is warmer.”
But also, Karowe points out a warmer lake is naturally not going to freeze as much. And we don’t have to wait for that change.
When the Lake freezes, that stops water from evaporating from the surface and coming back down as snow or rain. It’s why Arthur recalls the sun coming out in Charlevoix after the lake froze. More ice meant less lake effect snow, and fewer clouds. But Karowe says with less ice, “that means in principle at least that the opportunity for lake effect precipitation’s much greater.”
We didn’t see much of that this year, he added. “It’ll fluctuate from year to year,” he said. “But I think that at least over the next 30 years or so, it’s a pretty good assumption that we’ll see more lake effect snow.”
And after 30 years? Karowe says that depends on whether the goals of the Paris Agreement are met. If countries work together to slash carbon emissions and keep warming to about 2 degrees Celsius, Karowe doesn’t expect our seasons 80 years from now to look radically different. But if we don’t make those cuts, scientists predict “that by the end of the century about 80 percent of Michigan’s winter precipitation will be as rain. Not as snow.”
To sum up, The Great Lakes are warming, including Lake Michigan. That certainly could mean more evaporation, more lake effect snow and rain and presumably more clouds for Southwest Michigan.
As Arthur puts it, “warmer Lake, warmer air, more water in the warmer air.”