Lake Michigan surface temperature in November – hovering around 50 degrees – “really hot for this time of year” | PA

CHICAGO – A few weeks before the official start of the winter season, the surface temperatures of the Great Lakes are still above average, after summer and fall evenings that have not cooled down, a feature of climate change in Illinois.

“What was a little shocking was the consistency of warmer than normal conditions,” said state climatologist Trent Ford. “And the lack of cool nights.

Above-average temperatures have warmed the Great Lakes Basin all summer. Minnesota and Wisconsin recorded their third hottest June on record; parts of New York City, including Syracuse, experienced one of their hottest summers on record. Lake Huron warmed to nearly 74 degrees in late August, another record.

Illinois experienced an extended period of high minimum temperatures statewide in the summer and fall. The July-October average minimum temperature was the second highest on record in the state, lower than 2016, according to National Oceanic and Atmospheric Administration records dating back to 1895. The October average minimum temperature is the highest never recorded for the state – about 8 degrees above average.

This lack of cooling has spread to neighboring states, which also recorded high minimum temperatures in October, including Indiana, Michigan and Ohio. From June to October, Michigan and Ohio also experienced their highest average minimum temperature on record for that time period.

“Getting a record number of nights at 60 degrees or more in October is not like getting a record number of days at 100 degrees in July,” said Ford. “But there are definitely impacts to that, although they can be a bit more subtle.”

A severe frost did not cool much of the state until the last week of October, Ford said. The allergy season may have been longer than usual. Ticks and mosquitoes had more time to bite. Some areas have seen a delay in leaf color. Ford noticed it in his own backyard; he was picking tomatoes near Halloween.

The increase in minimum temperatures is a sign of the warmer and wetter conditions expected for Illinois, as human actions – the burning of fossil fuels and the resulting emissions – continue to fuel rapid climate change.

The most pronounced warming in Illinois has occurred during the winter season, and a continued decrease in extreme cold is predicted for the state. In parts of Illinois, minimum winter temperatures have already warmed by more than 3 degrees.

Last November in Chicago, in what the National Weather Service called a “remarkable stretch of heat,” a record-breaking week in the 1970s warmed the city, with two consecutive days reaching 76 degrees. The month ended as the hottest November 4th on record in Chicago. Overall it was the hottest November on record.

The approach of winter with warmer air temperatures may delay the cooling of lake temperatures. And warmer water that extends into winter can increase the potential for lake-effect snowfall, Ford said, as the difference in temperature gradients fuel winter storms. Lake effect snow tends to decrease with the onset of ice cover, but warmer waters can delay this as well.

Ice cover, which peaks between February and March in the Great Lakes, plays a key role in determining summer and fall conditions; last season’s maximum ice cover was below average. There is annual variability, but ice cover has declined in recent decades as the temperature of some lakes warms up faster than the air temperature.

The weak ice cover forecast for 2022 could prepare the Great Lakes for another summer and fall of above-average temperatures.

Due to changes in the strength of complex global sea-level pressure patterns, including a strong La Nina, the Great Lakes could see warm weather continuing into the winter season, said Jia Wang, ice climatologist at the NOAA Great Lakes Environmental Research Laboratory.

Above-average surface water temperatures and below-average ice cover are projected in the Great Lakes, Wang said.

Ice can lessen the effects of coastal erosion, a constant concern of Great Lakes communities, even though lake levels have declined from record levels. And warming waters – even the deep waters of Lake Michigan warm in winter – present their own ecological challenges, welcoming some invasive species, potentially fueling harmful algal blooms and transforming ecosystems.

According to National Oceanic and Atmospheric Administration CoastWatch data dating back to 1995, Lake Michigan’s surface temperature still tends to rise a few degrees above average. Throughout the fall, Lake Michigan experienced above-average temperatures, with temperatures in late November hovering around 50 degrees.

“Which is really hot for this time of year,” said Andrea Vander Woude, physics researcher at NOAA’s Great Lakes Environmental Research Laboratory.

Lake Michigan is not an anomaly; the Great Lakes as a whole are warmer than average.

All the lakes set records at the start of October, said Vander Woude. But particularly noticeable is the prolonged period of high temperatures.

“Study after study shows that the impacts of climate change that we are feeling here in Illinois, or Chicago in particular, are proportional to the amount of global warming,” said Ford. “The extent of climate change that we are seeing here in the state and the city is directly related to what is happening on a global level.”

Globally, even fractions of a degree can make the difference in avoiding the worst climate consequences. But after the big climate conference this month in Glasgow, Scotland, some experts left with little hope of staying within 1.5 degrees Celsius of warming – the threshold scientists warn against overtaking to avoid serious impacts.

In Illinois, scientists expect to see extremes, including unusually hot days, more intense rains and longer droughts, become more frequent. The average daily temperature has already risen by 2 degrees across much of the state, and an Illinois climate assessment found that a warming of 4 degrees or more is possible by the turn of the century, according to various emission scenarios.

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