Max Holmes grew up near the shores of Michigan's Grand Traverse Bay. He recalled playing on the frozen lake as a kid — ice skating, which he hated, and ice fishing with his family, which was a lot more fun.
But as the world warms, winters on Grand Traverse Bay — and many other lakes — aren't what they used to be. The bay recently had two ice-free years in a row, a change that Holmes — now a senior scientist at the Woodwell Climate Research Center in Woods Hole, Mass. — called "dramatic."
"I certainly know from all the work I do that climate change is happening, but this brought it home in a little bit different way," said Holmes, who primarily studies climate change in the Arctic. "This lake that I grew up on used to freeze, now it doesn't. You're losing something."
Grand Traverse Bay was one of 122 lakes worldwide included in a new study on disappearing lake ice. Researchers at York University in Toronto looked at nearly 80 years of lake-ice data from the National Snow and Ice Data Center, and counted the ice-free years. (If a lake did not have 100% ice cover for at least one day, the researchers considered it an ice-free year. The study did not account for the thickness or duration of the ice.) They found the number of ice-free winters among the lakes had more than tripled since 1978.
“This isn’t just happening in one lake in the northern United States,” said Alessandro Filazzola, lead author of the new study. “It’s happening in thousands of lakes around the world.”
While many lakes in New England — including New Hampshire's Lake Winnipesaukee and Massachusetts' Houghton's Pond — consistently froze over every year of the last 80, others did not. Maine's Sebago Lake went from freezing about 80% of the time, to only about half the time. Vermont's Lake Champlain used to freeze over two years out of three; now it's about one out of three.
Holmes, who was not involved in the study, said while the results were not surprising given the steady trend toward warmer winters, the amount and type of data the researchers used produced a "really powerful" study.
Study author Filazzola said he found the pace of the more recent changes "shocking."
"We noticed that even in the last two decades, there's a lot more lakes that are becoming ice-free," Filazzola said. "We're already observing patterns that are becoming more common."
Lost lake ice can have far-reaching ecological, cultural and economic impacts. Winter recreation activities like ice fishing derbies and ice festivals are an economic boon for many lake communities, for instance, and lakes without ice have more waves through the winter, leading to shoreline erosion. Lakes are also warmer in years without ice cover, making them more prone to toxic algae blooms that can harm fish, pets and people.
Filazzola said the trend toward less lake ice will likely continue.
"Even an extreme reduction of carbon emission won’t return us back to pre-1940s conditions," he said. "The best we can hope for is stabilizing at this level. But that doesn’t mean we shouldn’t do anything, because if we continue emitting the way we are, it’s going to get much worse."