ANCHORAGE — Anyone doubting the effects of human activity on global climate change should talk to the people of Alaska and the Yukon, U.S. Sen. John McCain said yesterday.

Fresh from a trip to Barrow, America's northernmost city, the Arizona senator said anecdotes from Alaskans and residents of the Yukon Territory confirm scientific evidence of global warming.

"We are convinced that the overwhelming scientific evidence indicated that climate change is taking place and human activities play a very large role," he said.

McCain, accompanied by Sens. Hillary Rodham Clinton, D-N.Y., Susan Collins, R-Maine, and Lindsey Graham, R-S.C., spoke to villagers in Canada whose spruce trees are being attacked by the northward spread of spruce beetles.

"I don't think there is any doubt left for anyone who actually looks at the science," Clinton said. "There are still some holdouts, but they are fighting a losing battle. The science is overwhelming, but what is deeply concerning is that climate change is accelerating."

Graham, who declared himself "on the fence" about climate-change legislation, said an academic debate about global warming is different in the far north. "If you can go to the Native people and listen to their stories and walk away with any doubt that something's going on, I just think you're not listening," he said.

McCain and Sen. Joe Lieberman, D-Conn., are sponsoring legislation to limit greenhouse-gas emissions from utilities and industry.

Opponents of the legislation, including Sen. Ted Stevens, R-Alaska, chairman of the Senate Commerce, Science and Transportation Committee, attribute warming to natural cycles.