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

Dennis Hession, mayor of Spokane, Wash., said it was one thing to see warming's effects in his own community and another to see it affect a whole ecosystem, as speakers indicated Sunday. In Spokane, winters have been warmer.

"That's all great for us," he said. "The question is, at what cost do we enjoy that?"

He said his trip to Alaska showed him his community needs to pay attention to effects elsewhere.

"There are real world impacts," he said. "There are direct impacts on people, businesses, cultures that we just don't see and are demonstrable."

Kitty Piercy, mayor of Eugene, Ore., said seeing effects of warming in Alaska gives her a stronger voice than just reading about them.

"This is a good way for me to talk to my community and keep moving us forward," Piercy said.

Pegeen Hanrahan, mayor of Gainesville, Fla., said changes don't have to be sold as reactions to global warming. The changes mayors are discussing are good for other reasons, she said.

Timing traffic lights saves gas for drivers. Changing them to LED lights saves power.

"I think everybody is going to come at this from a slightly different issue," she said.