In its latest global warming report, released this month, the Intergovernmental Panel on Climate Change said that minimum summer sea ice cover in the region has shrunk by about 7.4 percent a decade since the 1970s.
Large areas of the Arctic Ocean could be ice free by the end of this century, the panel warned.
Steger, with 40 years of experience as a polar explorer, bears witness to such changes.
"The weather is much more variable," he said. "You get more sun, more clouds, more storms—just crazy-type weather. We've experienced a lot of that this winter.
"It's unusually warm," he added.
At the time of the interview Steger reported the temperature to be about 23 degrees Fahrenheit (-5 degrees Celsius). Normally it would be about -20 degrees Fahrenheit (-29 degrees Celsius), he said.
Steger said the Arctic is probably warming faster than anywhere else because earlier springs and later falls have shortened the time period during which snow and ice extensively cover the region.
"The reflective snow and ice areas used to act as a mirror, reflecting sunlight [and thus heat] into outer space," he said. Less ice means the ground and water absorb more heat, creating a positive feedback loop.
To document the way such changes are affecting local cultures, the expedition will travel north up the east coast of Baffin Island before crossing the rugged central mountains and heading east.
Along the way the team plans to spend a week in each of five Inuit communities.
"These people are intuitively attuned to their surroundings and have good records in their oral history of what the winter once was," Steger said.
"Each community has a different story."
Already the three Inuit hunters who will be driving the team's dogsleds are only too aware of the threats, Steger said.
Their home village of Iglulik, the last stop on Steger's trip, has lost seven hunters to thinning sea ice in the last 18 months.
Steger said the intuition of these and other Arctic hunters—based on traditional signs such as wind direction—is being fatally undermined by the fast-changing climate.
"Hunters go out on the ice and it seems like it's going to be safe. But actually it's unsafe and the wind gets up and the ice breaks up," he said. "They make fatal errors. Their traditional knowledge is just not working anymore."
In addition to increased dangers, opportunities for hunting on the ice have been receding with the shortening winters, the Global Warming 101 team said.
Recent warming has reduced the hunting season in the region by 50 percent, expedition organizers noted on the Global Warming 101 Web site.
Caribou, walruses, seals, and fish such as Arctic char are the traditional mainstays of Arctic communities. But increasingly people have had to rely on grocery stores, Steger said.
These stores are expensive, the explorer added. But without them communities could face starvation.
Richard Branson is due to join the team for three weeks during the final 300-mile (480-kilometer) leg of the expedition.
The billionaire businessman said in a statement that he hopes the Global Warming 101 expedition "will contribute something to raising awareness of the uncertainties, risks, and effects of climate change before it is too late to save something of our frozen heritage at the poles."
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