LAKE PLACID — The strongest sign of a changing climate comes from ice.

Sea ice and glaciers, even at the highest elevations on Earth, are retreating faster than science has predicted.

It's taking weeks longer for ice to cover the lakes in the Northeast, if it does at all. Northern Lake Champlain doesn't freeze over every year anymore.

The most complete record of ice-over data in the North Country comes from ice-in dates recorded on Mirror Lake.

The lake, 128 acres in the heart of Lake Placid, is freezing two weeks later than it did 100 years ago.

Ice-in has been tracked since 1903. The data carries enough statistical relevance to be seen as a solid indicator of change.

SLOW FREEZE
Dr. Curt Stager, climate scientist at Paul Smith's College, is working with these numbers, amid tables of other weather data, to assess a changing Adirondack climate.

"Here, the lakes are warming, like the glaciers. It's the clearest sign we have so far that warming is coming to the Adirondacks."

As a scientist, Stager reads numbers after the fact.

He says science is the ultimate skeptic; it's the work of science to substantiate, not plan.

But climate science is under increasing pressure to inform policymakers so communities can make appropriate plans to adapt.

Stager sees the two-week change in freeze on Mirror Lake as a sign of bigger changes, pointing to a future when the lakes in the Adirondacks don't freeze over at all.

"The question will be how soon that happens; it could be on the order of a century or two. But throughout, you're shortening the time for recreational activities on Adirondack lakes."

There are other signs, too, of shifts in Adirondack climate, Stager said.

"Since 1975, June and September have warmed significantly — June, by almost 3 degrees Fahrenheit, and September has warmed a little more than 4.5 degrees."

Long-reaching impacts of this change aren't clear, but Stager suspects it has some effect on ice.

"I'm guessing, and this is speculative, but that's why the ice on the lakes is freezing later."

RECEDING GLACIERS
Stager's work in the Adirondacks is a telescopic view of ongoing global phenomenon.

Meeting with a group of scientists and reporters gathered recently at Ohio State University, Dr. Lonnie Thompson said retreating glaciers are the most striking evidence of a changing climate.

"They are like canaries in the coal mine for the global climate system. Glaciers integrate and respond to temperature, cloud cover, rain and radiation."

Fresh water stored in them provides humans with natural water towers.

And the increased pace of melting is causing oceans to rise.

If even 8 percent of glacial ice melts, New Orleans disappears, Thompson said.

Data suggests the oceans will rise a meter, about three feet, by the end of the 21st century.

"Climatologically, we are in unfamiliar territory, and the world's ice cover is responding dramatically," Thompson said.

"Unfortunately, for many of our high-elevation tropical glaciers, their fate has already been decided. The only question is, how long will it take?"

PREDICTIONS
The world's leading glaciologist, Thompson has spent 40 years studying ice and ancient climates trapped in air bubbles, pulling ice cores from glaciers around the planet.

By 2020, he predicts, there will be no ice at all on Mount Kilimanjaro in Kenya. And in 30 years, there will be no glaciers in Glacier National Park.

The vast majority of scientists agree that greenhouse gases from human industry have pushed normal climate change toward a tipping point.

Dr. Ian Hawitt, on Thompson's staff at Byrd Polar Research Center, likened the situation to a one-armed boxing match between Earth's climate and ice sheets.

"Every 50 years, climate punches the ice sheet," Hawitt said.

And for thousands of years, ice recovered between punches.

"But now it's a climate on steroids," Hawitt said. "And in 20 or 30 years, it will deliver another punch that will be even harder. We can see this change, but it's part of a larger signal we don't understand."

CRUCIAL TIME
Many scientists say 2009 is a pivotal year for setting policy to address the changing climate, both in energy conservation and in adaptation.

Stager will present the dinner address for the Adirondack Response to Climate Change conference at the Wild Center in Tupper Lake on Tuesday and Wednesday.

His topic centers on climate skeptics.

"The main theme is going to be, while science is pretty firmly demonstrating climate change is under way, there is still room for healthy skepticism, and how do we distinguish the two?"

E-mail Kim Smith Dedam at: kdedam@pressrepublican.com