Climate Change to blame for high Lake Michigan water levels

Photo: Near record Lake Michigan water levels threaten to inundate the beach and staircase at Camps Leelanau & Kohana north of Glen Arbor.

By Linda Alice Dewey

Sun contributor

Some seek to explain what is happening with our Great Lakes water levels as a natural cycle. They point to other swings in water levels over the past 100 years. But what is happening now has not, in fact, ever happened before. Here’s how it’s different, and why.

In May 2019, Lake Michigan-Huron, considered one body of water hydrologically because the lakes are joined at the straits, rose 9 inches. That’s nine verticalinches. This brought it to within 6 inches of the all-time record set in October 1986. 

Heavy June rains ensured continued rising water, and, as of June 21, it did, in fact, hit a new June record. The other Great Lakes broke records as well.

According to Dr. Andrew Gronewold, associate professor at the University of Michigan’s School for Environment and Sustainability in the Department of Civil and Environmental Engineering, the Great Lakes’ water levels are driven by three factors: precipitation (rain and snow), evaporation (due to air and water temperatures), and runoff (influenced by precipitation over land, snow cover, and soil moisture). Gronewoldwas a hydrologist and physical scientist at the National Oceanic and Atmospheric Administration (NOAA) Great Lakes Environmental Research Laboratory prior to U of M. He has a Ph.D. from Duke and a B.S. from Cornell.

Recently, there’s been an obvious increase in rain and snow. Add to that our below-average temperatures this past winter and spring, which resulted in lower evaporation rates, and lake water levels increased.

These things happen, right? You get more precipitation for a period of time, then a few years of less. Temperatures rise and fall. We had hot summers the past several years, but this year is cold, and what about that Polar Vortex of 2014?

Turning point 

Let’s look at that Polar Vortex of 2014. It seems to be the turning point from record low lake levels in 2013 to these current record highs.  

At that time, we had just come off a 15-year period of water levels so low that ships couldn’t come into port in Duluth. There were big problems with the rivers, and hydrologists were studying methods of changing navigation methods on our waterways. Great Lakes communities were becoming more protective of their fresh water, which is, after all, approximately 20% of the total fresh water on earth.

Yet during those 15 years, we did have increasingly frequent heavy rain and snow events. Even so, that precipitation was counteracted by very warm weather and Great Lakes higher water temperatures, which led to greater evaporation. The lakes diminished but for a new reason. 

Something had already changed. Prior to this, lake levels generally went up and down parallel with precipitation levels. Now the warmer air and water temperatures were coming more into play, monkeying with normal seasonal levels of evaporation. It might rain, but the water didn’t rise.

“The reason water levels didn’t go up is because of the extraordinary period of evaporation,” Dr. Gronewold told the Sun. So, our water began to dry up—until 2013, when that long period of evaporation stopped. “And the reason it stopped? The switch got flipped.”

Enter the Polar Vortex of 2014. The entire world was affected. “The Arctic polar vortex that year is not a Great Lakes thing,” Gronewold said. “That’s a global phenomenon.” He explained that it had to do with warm air over the Arctic pushing the Polar Vortex air mass so it wobbled out of place.

Unprecedented

In 2014, the jet stream really wobbled. “Scientists tell us that the extent that the air mass wobbled, and the instability of that … affected the entire] region,” Gronewold said. “That sequence of events never happened before.” In fact, he added, those two water level drivers, “the evaporation and the cold snap that stopped it? That never happened before.” 

We had a 15-year period of intense evaporation followed by a cold snap (the Polar Vortex) in a sequence that was unprecedented. The weather turned. Quickly. 

The ensuing Polar Vortex of 2014 covered the Great Lakes in ice. Icebergs floated around into May, and water temperatures never really recuperated that summer. 

Lake levels rose at an unprecedented rate from 2014-2016, the fastest of any two-year period on record (since 1919). They’ve been on an upward climb since. 

This year, cooler temps have brought more precipitation. According to NOAA, the past 12 months have been“the wettest 12–month period on record in the U.S., with 37.68 inches, 7.73 inch above average.”

The rapidity of the change in water levels alone sets our current pattern apart from previous cycles. Usually, a cycle occurs over 20-30 years. We have just witnessed a swing between two extremes in less than six years.

This, in itself, indicates a change. The range is new and the speed of the swing is new. “If you have events that are not part of your historical record that represent a change in conditions, that’sthe definition of climate change,” said Gronewold.

Now, instead of dredging and searching for ways to bring ships to docks, many of those docks and piers are under water. Here in Leelanau, it affects tourist activities. People go home if it’s rainy or cool. Beach walkers can no longer walk along some of their favorite Lake Michigan beaches. Events like Fishtown’s fundraiser kickoff to raise Fishtown from the rising water are being moved or cancelled. 

Landowners along Lake Michigan’s coast are losing measurable real estate. Some riparians are taking things into their own hands by clearing sea grass down to the water so they’ll have a beach. There, survey stakes marking the Ordinary High Water Mark, (581.5 feet above sea level) which normally indicates the legal boundary beginning the public portion of the beach, is in the water anyway.

Away from the shore, Leelanau’s water table is rising. Many property owners, who built homes in low areas during dry years, find themselves digging moats around their homes, then filling them with gravel and installing sump pumps. In the forests, swaths of land that hadn’t seen water in 30 years are covered with water once again. Smaller streams leading to Lake Michigan are still. If they’re not moving, says Leelanau drain commissioner Steve Christensen, they’re backing up.

New pattern, “new normal”

We haven’t seen the end of it. The Army Corps of Engineers, which keeps tabs on Great Lakes levels, predicted on June 21 that Lake Michigan-Huron will be 15 inches above its average for June 2018. And that, you’ll remember, was already high. Levels are expected to match 1986 levels for July and August, as well. That means they’ll continue to rise. We’ll see what the fall brings.

Our Great Lakes regional weather—and lake levels—will probably continue to swing from high to low, and perhaps from cold to hot, but Dr. Gronewold and his colleagues believe the lakes’ cycles will become more rapid and extreme. 

On June 10, Gronewold published an article in Earth & Space Science News, titled “Climate change is driving rapid shifts between high and low water levels on the Great Lakes.” In it, he and co-author, hydrology and climate science researcher Richard Rood, state, “[W]e believe rapid transitions between extreme high and low water levels in the Great Lakes represent the ‘new normal … Increasing precipitation, the threat of recurring periods of high evaporation, and a combination of both routine and unusual climate events — such as extreme cold air outbursts — are putting the region in uncharted territory.”