For the 34 million people who call the US’s Great Lakes region home, last winter was a particularly gloomy one due to a dearth of sunlight – a reality that could afflict residents’ mental health in years to come.
Grand Rapids, Michigan, saw just five minutes of sun during the first eight days of January 2023. The same month was the cloudiest January in Chicago in 129 years. At one stage, the 6.3 million people living in the greater Toronto area didn’t see the sun for more than three weeks.
These observations aren’t just anecdotes. Research by the European Centre for Medium-Range Weather Forecasts found that January 2023 was one of the cloudiest for a number of Great Lakes cities since 1950.
While experts say it’s difficult to establish a direct link between climate change and wintertime cloud cover, unfrozen lakes allow moisture to be absorbed from the water into the atmosphere, which can then fuel clouds and lake-effect snow.
“[Last winter] clouds were extreme over much of the Great Lakes states, coinciding with extremely low ice cover over the Great Lakes,” says Steve Vavrus, the Wisconsin state climatologist and director of the state’s climatology office.
“We know that open lakes favor more snowfall because more evaporation occurs over ice-free waters.”
The five Great Lakes have been experiencing less ice formation for decades. While the average ice cover at the turn of the year was 9%, there was just 0.4% observed on 1 January this year, the lowest since records began in 1973.
That has serious mental health implications for the millions of people who live on or close to the Great Lakes. Experts say less sunlight could produce negative mental health consequences for people, according to experts.
“Seasonal affective disorder (Sad) is linked to changes in light, so cloud cover can have a significant impact on someone’s mood,” Dr Kia-Rai Prewitt, a psychologist at Cleveland Clinic in Ohio, said.
“People may notice they feel more depressed, have low energy, sleep more, overeat, crave carbohydrates and engage less with others, especially during the winter and fall months.”
About 5% of American adults suffer from seasonal affective disorder, a form of depression linked to reduced access to sunlight in winter, according to the American Psychiatric Association.
While the exact cause of Sad isn’t known, less access to sunlight is thought to play a significant role.
“Sad is more common for people who live in parts of the country that have fewer daylight hours,” Prewitt said, adding that her home town of Cleveland “is definitely one of those areas of the country”.
One study based on Google search results and other information found that three of the top five US states where residents researched terms such as “seasonal depression” and “seasonal affective disorder” are in the Great Lakes region. Ohio – which borders Lake Erie for 262 miles (421.7km) along its southern shoreline – ranked second, after Alaska. Minnesota and Michigan are the other two Great Lakes states in the top five.
Research covering 1998 to 2016 by the National Renewable Energy Laboratory shows that Great Lakes states and Ontario experience far low levels of radiant energy from the sun compared to the rest of North America.
While Cleveland and Chicago may be infamous for their winter cloud cover, their relatively low latitude means they see more daylight during the depths of winter than many other regional metropolitan centers.
Duluth, Minnesota, and Thunder Bay, Ontario – cities on the shore of Lake Superior, the Great Lakes’ most northerly body of water – get only about 9hrs and 15min of daylight at this time of the year. Even other dreary northern cities such as New York City – by comparison – receive 30 more minutes of daylight a day.
And although scientists say that a difficulty in simulating clouds in research modeling makes it hard to definitively say that cloudier days are a certainty in the years to come, it is likely that will be the case.
“The possible direction of causality (linking climate change to increased cloud cover) is hard to determine because while the open lakes may have contributed to the cloudiness regionally, winter clouds also help to keep the lakes warmer than usual,” said Vavrus, the Wisconsin state climatologist.
“That said … less ice on the Great Lakes should favor more cloudiness, both locally and downstream of the lakes.”
Declining ice cover that has already fallen by 71% between 1973 and 2010 is likely to continue in the decades ahead. Experts add that ice will probably form only in the Great Lakes’ shallowest parts, such as the western basin of Lake Erie – where the water is 25 to 30ft deep – or along the lakes’ shorelines. Despite the recent Arctic air blast that brought sub-zero temperatures to much of North America, ice cover on Lake Erie is well below the historical average. Ice on the far larger, deeper Lake Superior lags even further behind.
“The seasonality, thickness and duration of the ice will change,” said Richard Rood, professor emeritus of climate and space sciences and engineering at the University of Michigan, who notes that the cause is global warming from carbon dioxide and methane gas releases.
“We are likely to see the formation of ice, primarily, with short-term weather events, cold air outbreaks, in midwinter. This ice will be quite different in character than the persistent, seasonal ice common prior to 2000.”