SEWARD, Alaska — Vanta Shafer says it used to be a shorter walk to see Exit Glacier 14 years ago when she was a mother entertaining her children and not the mayor of nearby Seward.

Since then, the glacier has retreated hundreds of feet, almost too far to walk to, Shafer said.

"I feel sad to come out here anymore," she said of the glacier's retreat. "Don't you think that's awfully fast?"

Salt Lake City Mayor Rocky Anderson and more than 30 other U.S. mayors from 17 states had the chance to ponder that question Sunday and consider whether the glacier's retreat is linked to global warming. They are attending a three-day conference, "Strengthening Our Cities: Mayors Responding to Global Climate Change."

The sessions are being sponsored by the International Council for Local Environmental Initiatives, the municipality of Anchorage and the U.S. Conference of Mayors.

Sunday was the day for demonstrating the effects of warming, which are more pronounced near the Earth's poles, according to researchers.

Mayors looked at forests of white spruce bedeviled by destructive beetles that mature in one year instead of two because of warmer weather. They heard of tree lines creeping farther up Alaska mountainsides and farther north above the Arctic Circle. They heard that global sea levels are rising and a major reason is increasing temperatures, which cause water to expand. And they heard that 30 of the 32 named glaciers fed by the 700-square-mile Harding Ice Field, including Exit Glacier, are thinning and retreating.

Anderson said the issue grabbed him after he read a book by former Vice President Al Gore, "Earth in the Balance." He then became concerned by the lack of effective action to deal with the problem, he said, even as other issues, such as the elimination of ozone-depleting substances, were addressed.

"I kept expecting to see that kind of international problem-solving on the issue of global warming," he said. "Unfortunately, this country, along with Australia, has utterly failed in that regard."

Neither has signed the Kyoto Agreement, in which countries pledged to reduce their greenhouse gas emissions.

"The problems are urgent and require urgent and effective actions," he said.

Anderson said improved air quality, enhanced public health, fuel price fluctuations, national security, energy independence and global warming all could be addressed by focusing on two solutions: more conservation and efficiencies, and clean, renewable sources of energy.

Just as the world moved from the horse and buggy era to the Industrial Revolution, it must change again, away from fossil fuels, he said.

"It's time now that we move into the next stage," he said.