Iqaluit (Aug 28/06) - There are troubling signs of climate change on the bottoms of Nunavut's Northern lakes, according to a prominent scientist.

On the heels of 5,000 years of "relative stability," the past century has brought radical change in lake sediment, said John Smol, a professor in the department of biology at Queen's University in Kingston, Ont.

"I would argue that nothing has happened like we're seeing now," Smol said upon returning from three weeks of gathering additional data on Devon Island.

As temperatures continue to rise, Northern lakes are thawing for longer periods, thereby allowing different types of organisms to settle at the bottom. Over the past 100 years, the layers of sediment - containing carbon particles, pollen grains, mineral particles, insect remains, fossils and other substances - have varied greatly from the distant past, which is represented by the deeper deposits, Smol's analysis has shown.

This underwater source of long-term information is crucial because it's one of the few people can access, Smol said. Environment Canada's temperature readings in the Arctic, for example, only date back about 50 years.

Other changes in the Northern ecosystem include more mosses and nutrient values and higher pH levels (referring to alkalinity and acidity).

Smol also attributes these deviations primarily to climate warming. The Arctic, he noted, is considered a bell-weather or "early warning" system for elsewhere in the world.

If no action is taken, he envisions a loss of habitat, major decreases in sea ice, and water levels rising globally, causing flooding.

"We have to do something," said Smol, who is Canada's research chairperson in environmental change and has been conducting studies in the Arctic for 24 years.

"The consequences are horrendous if we're not taking action."

Weaning ourselves off of greenhouse-producing fuels would be a wise move, he said.

Most of the 30 people at the recent presentation, held at the Nunatta Sunakkutaangit museum, seemed receptive to the message.

But one man, who refused to give his name publicly, repeatedly challenged the researchers on their assertions. The man admitted to being somewhat of a skeptic.

"I hate to see anybody state (human-caused climate change) as fact. It's a theory," he said, but acknowledged that it has considerable support.

He made reference to flooding in southern Manitoba over the past several decades that has been blamed on global warming, but pointed out that the greatest flood occurred in the 1800s, prior to the phenomenon.

Smol conceded that there are "multiple stressors" on the environment, making it difficult if not impossible to study any one of those factors in isolation. Yet he also noted that, historically, scientists have tended to understate potential perils.

He suggested that human innovation could lead to a solution.

He cited the example of cloro-fluoro carbons (CFCs), which were found to cause ozone depletion.

Manufacturers have not only rid their products of the chemicals, but have found better and cheaper alternatives, said Smol.