A MARTINEZ, HOST:
Climate change has contributed to reducing ice on northern lakes and ponds in wintertime with important consequences for their ecosystems. Reporter Emma Jacobs introduces us to some of the citizen scientists helping to document those changes in the northern U.S.
EMMA JACOBS, BYLINE: In the 1980s, an enthusiastic lake researcher named Ken Stewart started looking for volunteers.
GERALD BOVE: He would recruit people using the local chamber of commerce, sporting goods stores. He would go in and speak to people about who might live on a lake.
JACOBS: This is Stewart's former student, Gerald Bove. He says Stewart's recruits started recording the dates of the winter freeze and spring thaw for their lakes, more than a thousand across five northern states. They sent them by postcard to Stewart, nicknamed the Ice Man by his colleagues at the University at Buffalo.
BOVE: His wife, Ardis (ph), made him retire from actually going out on the ice at some point in his early 80s. She said, I really don't want you going out on too many more frozen lakes.
JACOBS: Stewart's now 90. But his network is still collecting data.
DOUG FITZGERALD: So there's a little skim of ice here. Not right there.
JACOBS: Doug Fitzgerald (ph) has trudged out by foot and in his truck to track seven lakes and ponds in northern New York since 1992.
FITZGERALD: Well, I was a young man when I started. So (laughter) now, not so much. So...
JACOBS: Air temperature is, of course, key for water to freeze. But Fitzgerald's lakes all lie within a seven-mile radius and still freeze on different dates because some are deeper or more exposed to wind or light.
FITZGERALD: There's one pond where there's a distinct flow of water through. So that stays open longer. So I do make a judgment call on that. But what I try to do is be consistent every year.
JACOBS: Consistent so it's useful to scientists, like Sapna Sharma, an ecologist at York University in Toronto.
SAPNA SHARMA: Ice acts like a lid for a lake. You can think of it acts like a lid on a lake in the winter.
JACOBS: Sharma has come on to co-run the lake ice project. She explains the number of days ice covers the surface, days that lid is on, has year-round impacts on water quality and temperature.
SHARMA: What's happening to your dissolved oxygen levels in the lake? Oxygen is incredibly important for all those creatures living in the lake.
JACOBS: Her recent research has shown ice season is getting shorter across the northern hemisphere. And that trend is speeding up. She says tens of thousands of lakes could stop freezing consistently even under optimistic warming scenarios. She says analysis of the volunteers' data could help forecast how fast individual lakes and local ecosystems will change.
NANCY QUILLIAN: OK. So the white house is where I lived when I was born.
JACOBS: Nancy Quillian (ph) has lived her whole life with a view of Glen Lake in Queensbury, N.Y. She's sent in data for decades without thinking too much about it but noticed some change herself.
QUILLIAN: My memory as a kid is we were always skating by Christmas. And now it's a little iffy.
JACOBS: At 73, she also notes another challenge facing the new heads of the research effort, bringing on a new generation of data gatherers.
QUILLIAN: Probably should pass it on to somebody much younger (laughter).
JACOBS: Someday, there may no longer be dates to record for Glen Lake if it's among those that stop freezing altogether. Then the data would become a historical record of a past era in North American winters.
For NPR News, I'm Emma Jacobs.
[POST-BROADCAST CORRECTION: Gerald Bove, identified in this story as a "former student," is now a research scientist at the University of the Virgin Islands and co-runs the lake ice research project with Sapna Sharma.]
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