PORTLAND, Ore. — Senator John McCain sought to distance himself from President Bush on Monday as he called for a mandatory limit on greenhouse gas emissions in the United States.

Mr. McCain, the presumptive Republican presidential nominee, also pledged to work with the European Union to impose punitive tariffs on China and India, two of the world’s biggest polluters, if those nations refused to participate in an international agreement to slow global warming.


In what his campaign promoted as a major speech on climate change, the Arizona senator renewed his support for a “cap-and-trade” system in which power plants and other polluters could meet limits on greenhouse gases by either reducing emissions on their own or buying credits from more efficient producers.

“Instead of idly debating the precise extent of global warming or the precise timeline of global warming, we need to deal with the central facts of rising temperatures, rising waters and all the endless troubles that global warming will bring,” Mr. McCain said at a wind power plant in Oregon, a state that is expected to be a political battleground in the general election and where the environment is a central issue for voters. “We stand warned by serious and credible scientists across the world that time is short and the dangers are great.”

Mr. McCain added pointedly: “I will not shirk the mantle of leadership that the United States bears. I will not permit eight long years to pass without serious action on serious challenges. The most relevant question now is whether our own government is equal to the challenge.”