A map is always a good place to start. I live in Michigan’s lower peninsula (the mitten), at the southeast corner.
Here are some fun facts about the great Great Lakes.
Lake Superior is the largest freshwater lake in the world by surface area [at almost 32,000 square miles].
Lake Michigan’s shore is home to the largest freshwater sand dunes in the world.
The Great Lakes are the largest freshwater system in the world [with] more than 20% of all the world’s freshwater.
Lake Superior contains half of the water in all the Great Lakes.
Michigan has the most freshwater coastline of any U.S. state.
[The Great Lakes region] accounts for more than 90% of the surface fresh water in the United States.
During the more than 20 years I worked in downtown Detroit, I frequently watched the Detroit River from my 19th floor perch. I took lunchtime strolls along the Detroit Riverwalk, getting a closer view. I looked forward to the first fishing boat sighting as a sign of spring. And I was always on the lookout for the big freighters, like the Paul R. Tregurtha, the “Queen of the Lakes” at 1,013 feet long.
Wintertime brought the ice watch. Some winters I could see none. A couple winters were cold enough that snowmobilers ventured onto the river, with ice covering the entire width and not moving for weeks. Some years looked to be ice-free, yet a cold snap saw ice forming fairly quickly.
This winter, thanks to retirement and good health, I’ve braved the weather to get a closer look at ice forming on the river and on Lakes Erie and St. Clair. Here’s a map of my patch of the Great Lakes-- the small area along the base of the mitten’s thumb, from the heart-shaped Lake St. Clair to the Detroit River and Lake Erie.
My limited observations got me wondering about long term trends. OceanDiver gave me a gentle hint that this might make a good Bucket topic, and reminded me of the late Bucketeer Dr Arcadia, who used to report on Great Lakes ice cover. So, in memory of Dr Arcadia, I put together this update.
The depth of the lakes is a big factor in ice formation. This profile shows the depth of the Great Lakes water system all the way to the Atlantic Ocean. Given the relative shallowness of Lake St. Clair and Lake Erie, it’s not surprising that I’ve seen rapid ice formation this year. But what about the rest of the lakes?
I found a wealth of information at the U.S. National Ice Center (USNIC). This multi-agency organization, primarily with the U.S. Navy, NOAA and the U.S. Coast Guard, monitors ice globally, including in the Arctic Ocean, Antarctica, and lucky for me, the Great Lakes. With assistance from the Canadian Ice Center, USNIC posts daily maps of Great Lakes ice concentration (top left) and thickness (top right), with both combined in the lower right map. Last year’s ice on that date is in the lower left panel for comparison.
The Canadian Ice Center also assists USNIC in producing forecasts. These include a 30-day forecast twice a month, an annual seasonal outlook, and a season end summary. They also have a text version of current and near-term conditions. Today’s ice is far ahead of the ice at this time last year.
But if there’s one thing I’ve learned from observation and researching this Bucket, it’s that there is a lot of variation from year to year. This January 24, 2022 chart from NOAA shows average Great Lakes ice cover, this year’s ice to date, and past years back to 1973, when it first started keeping records.
Ice formation this season started late, but is heading to be an average year. It went from just below average to above average in five days.
This link from NOAA’s Great Lakes Environmental Research Laboratory has a nifty animated map of Great Lakes ice formation, also going back to 1973.
That left me wondering what the long term trend is. This next graph shows that there’s cause for concern.
To understand what this downward trend might mean, I turned to Great Lakes Integrated Sciences and Assessments (GLISA). GLISA is a NOAA supported program that
works at the boundary between climate science and decision-makers, striving to enhance Great Lakes Communities’ capacity to understand, plan for, and respond to climate impacts now and in the future.
The program targets decision-makers in agriculture, cities and Tribal communities, and has an impressive 175 partners across the U.S. Here’s a summary of some of their findings about the steady loss of winter ice:
The number of days per winter with lake ice coverage has declined since the start of record in 1973.
In most areas, ice coverage declines were a sudden shift as opposed to a gradual decline. For Lakes Michigan, Erie, and Ontario the shift occurred in the mid-1980s, but for Lakes Superior and Huron the shift occurred during the 1997/98 winter.
Ice cover has decreased the most in the north (i.e., Lake Superior, Northern Lake Michigan and Huron) and in coastal areas.
Ice cover on the Great Lakes will likely continue to decrease in the future, however, these decreases are expected to be interrupted by high-ice winters associated with cold air outbreaks.
Reduced ice cover results in more winter lake-effect precipitation and increased winter wave activity.
According to GLISA, the effects of the reduced ice cover include:
The surface water temperature of the Great Lakes is warming faster than area air temperature.
Shorter winters and less ice amplify the trend of those warmer summer air temperatures.
Less ice means more evaporation over winter, which lowers lake levels.
Warmer water means less protection for plankton and native cold-water fish.
Less ice coverage also means more lake stratification, with warmer and longer summers in turn warming upper water strata. More lake stratification means that
oxygen can become depleted in the lakes’ productive lower levels, leading to “dead zones”. Increases in extreme precipitation, runoff, and nutrient loading can create conditions favorable to toxic algal bloom formation.
Not everyone is a fan of ice. Even this early in the ice season, waterfront homeowners and Great Lakes shipping companies have their headaches. The ice collects at narrow points, like along the St. Clair River, and at Lake St. Clair where the Detroit River starts. Wind can exacerbate the situation by pushing the ice, as this news report shows. That means water backs up behind the ice. This year’s ice has already prompted a recent flood advisory for Lake St. Clair.
The sustained cold, like we’ve experienced the past few weeks, means thicker ice, making freighter passage hazardous. Two freighters have had to be rescued by the Canadian Coast Guard after getting ice bound on the St. Clair River. Depending on where the ice forms and the thickness, shipping can come to a halt. In 2020, opening day didn’t come until March 25th. Hmmm. Two more months maybe. Spring sure seems like a long ways off in SE Michigan.
So that’s the exciting world of Great Lakes winter ice. What’s up in nature in your area?
The Daily Bucket is a nature refuge. We amicably discuss animals, weather, climate, soil, plants, waters and note life’s patterns.
We invite you to note what you are seeing around you in your own part of the world, and to share your observations in the comments below.
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