Earliest recorded ’ice-out’ date on Douglas Lake at U-M Biological Station in northern Michigan

PELLSTON-The earliest "ice-out- ever recorded on Douglas Lake at the University of Michigan Biological Station occurred last month, setting another record for the mild winter in northern Michigan.

The ice-out, declared on March 16 this year, comes after the latest-recorded Douglas Lake "ice-in- occurred on Jan. 6-making this the shortest season of lake ice cover recorded at the U-M Biological Station, at 70 days.

For 93 years, scientists at the Biological Station, the 10,000-acre research and teaching campus nestled along Douglas Lake near Pellston in the northern Lower Peninsula, have made the calls based on their observations of the lake.

The Douglas Lake ice-out date is when consensus determines that 75% of ice cover is gone from South Fishtail Bay, the deepest part of the south end of the lake. The ice-in date is when 75% of the bay is covered in ice.

The historic field station, founded in 1909, has maintained statistics on ice-out dates for Douglas Lake dating back to 1931.

Previously, the record for earliest ice-out was March 20, 2012.

Last year’s ice-out date on Douglas Lake was April 13, 2023. Ten years ago, ice-out was declared on April 29, 2014. In 1996, it was May 4. Fifty years ago, it was April 21, 1974. In 1931, ice-out was declared on April 12.

Adam Schubel, the Biological Station’s resident biologist, said winter weather has been "variable or noisy- during his eight years there.

When he returned from a family vacation in mid-March, Schubel was surprised to see that he’d have to again move up the annual staff contest to guess the spring ice-out date.

"Historically the deadline for our contest was March 25, but we’ve moved it up earlier each of the past three years,- Schubel said. "The variability is what makes it a riveting contest.-

In the long term, there’s only a slight trend toward earlier ice-out-about one day per decade. But in the short term, this year’s ice-out was 45 days earlier than it was just six years ago.

"We had close to our latest ever recorded ice-out in 2018, which was on May 1,- Schubel said.

On March 13, three days before declaring ice-out on Douglas Lake this year, Schubel had to hop over a liquid gap at the beach to lightly tread out to the historic ice thickness measuring site, where he measured an ice thickness of 5.5 inches.

"It was melting remarkably fast,- he said. "Temperature was the primary driver. Wind seemed to be a major factor near the end, when the ice sheet had broken up.-

Schubel and John Lenters, senior research specialist at the Biological Station, both won the 2024 trophy three days later.

"Interestingly, the bay iced in on Dec. 1, 2023, and then melted less than two weeks later on Dec. 10. Then it iced in for the season on Jan. 6, 2024,- Schubel said. "It’s done something like this the past two years. One thing I note from my observations is that waterfowl seem to appear on open water immediately, whenever it appears, as if they’re just monitoring lakes, waiting for them to thaw.-

Lenters studies changing winters in Michigan. He has a long-term interest in understanding the effects of changing lake temperature and ice cover on Great Lakes evaporation.

"It’s been a very warm winter throughout much of the Midwest this year, which is what we typically expect to see during an El Niño,- Lenters said. "But this year broke a lot of records, and it was even warmer than past strong El Niños such as 1997-98 and 2015-16. So what we saw this year was a combination of El Niño with the long-term warming effects of climate change. Sort of a double whammy.-

The U-M Biological Station has been home to scientific discovery since its founding in 1909. Its core mission is to advance environmental field research, engage students in scientific discovery and provide information needed to understand and sustain ecosystems from local to global scales.

In the station’s cross-disciplinary, interactive community, students, faculty and researchers from around the globe come together to learn about and from the natural world and to seek solutions to the critical environmental challenges of our time.