Some speakers said scientific evidence supports the listing and urged the U.S. Fish and Wildlife Service to adopt protections so polar bears would be present for future generations.
"We need to ultimately recognize the threat that global warming poses not just to polar bears but countless other species, from Caribbean corals to the California butterflies to us as well," said Melissa Waage of the Center for Biological Diversity at Monday night's hearing.
But others said listing the polar bear as threatened could hurt the hunting industry, whose revenues help local economies.
"The scientific underpinnings of the proposal are woefully inadequate," said Richard Krause, senior director of regulatory relations for the American Farm Bureau Federation. "Rather than basing the proposal on direct scientific observations, the Service bases its proposal on speculative predictions and assumptions that may or may not be valid."
The Fish and Wildlife Service's review comes amid concerns that global warming is melting away the icy habitats where the animals live. In December, Interior Secretary Dirk Kempthorne proposed listing polar bears as a threatened species.
If the polar bear were listed as a threatened species, all federal agencies would have to ensure that anything they authorize that might affect polar bears will not jeopardize their survival or the sea ice where they live. That could include oil and gas exploration, commercial shipping or even releases of toxic contaminants or climate-affecting pollution.
Environmentalists hope that invoking the Endangered Species Act protections might eventually lead the government to reduce carbon dioxide emissions and other heat-trapping "greenhouse" gases blamed for warming the atmosphere.
"The Interior Deparment has pretty much explicitly said that they don't think they have the authority to regulate greenhouse gas emission, but we know that the Endangered Species Act goes well beyond these walls, that it's taken into account by other agencies," said Kert Davies, research director for Greenpeace.
Chris Miller, a real estate agent from Woodbridge, Virginia, expressed a personal connection to the animal after she came face to face with a polar bear on a trip to Canada.
"I feel I have a responsibility," Miller said. "He gave me a second chance and I feel I owe it to them to try to give back."
About 30 people in the crowd showed their support for the animal by sporting orange life perservers and white baseball caps with a polar bear face and ears. One of them, 8-year-old Kate Muffett of Washington, said, "I am also affected by polar bears disappearing for I would love to see polar bears."
But Patterk Netser, an environmental minister for the Nunavut Territory of Canada, said: "They are not endangered. They are not threatened at the moment. We have an abudance of them in our area."
A final decision on the listing is due by January 2008. The Fish and Wildlife Service is taking public comments on the proposed listing until April 9. It held a public hearing last week in Anchorage, Alaska, and another is scheduled for Wednesday in Barrow, Alaska, reports AP.
Greenland and Norway have the most polar bears, while a quarter of them live mainly in Alaska and travel to Canada and Russia.