OTTAWA - The leaders of the world's wealthiest countries are headed for a showdown next month on how to tackle climate change, with the United States pitted against European nations on how to move forward.

Where Canada stands on this major rift remains a mystery leading up to the G8 meetings in Heiligendamm, Germany, beginning June 6.

The three days of meetings are widely regarded as a bellwether for the success of the United Nations-led efforts to start a second phase of the Kyoto Protocol on climate change. Talks on that second phase, which would include countries such as India and China, begin December in Bali.

International news agencies reported Friday the United States was balking at the text of a final statement from the G8 meeting, being drafted now by representatives from the various countries including Canada. The U.S. is opposed to any commitment that mentions targets or a date for reducing global greenhouse-gas emissions.

Washington also wants removed a statement of support for carbon trading markets, and will not support a line that reaffirms the negotiating mandate of the Bali talks for an international agreement with a deadline of 2009.

Environment Minister John Baird was asked about the controversy Sunday, but did not specifically comment on the U.S. position. He said he saw Canada acting as a "bridge" between the divergent opinions.

"We need a genuine effort to get the United States, China, India to join with Canada and other European countries on worldwide efforts to reduce greenhouse-gas emissions," Baird said in Toronto.

"But we've got to take action at home. Talk is cheap. Canadians have seen too much talk and not enough action, and we're committed to the action side."

Baird also said Canada supports the European-backed idea of a 50 per cent reduction in greenhouse-gas emissions by 2050, although he uses a much different base year for the reduction: 2006 versus 1990.

He has said in the past that Canada supports the Kyoto process and the United Nations' role in it.

A spokesman for Foreign Affairs Minister Peter MacKay, whose department is involved in the drafting of the G8 declaration, would not comment.

Louise Comeau of the Sage Centre's climate project interpreted Baird's remarks about Canada acting as a bridge as meaning the Conservative government will inevitably help water down G8 declaration by insisting Washington's views be included.

She said the biggest threat posed by the U.S. is to the United Nations' role as the main forum for striking an international agreement. She wants Canada to come out forcefully in defence of the UN process.

"There's nothing unreasonable in the German proposals and Canada should be supporting them," said Comeau. "If that means Canada isolating the U.S. this time around, then that's what we have to do."

Liberal Leader Stephane Dion sent an open letter to Prime Minister Stephen Harper over the weekend, urging him to take a hard stand against Washington's position.

"I am deeply troubled by Canada's silence in the face of recent reports that U.S. President George Bush is seeking to weaken the proposed G8 Declaration on Climate Change and Energy Efficiency," Dion wrote.

"I am writing to urge you to recognize the moral imperative of urgent action, to seize the mantle of international leadership, and to speak out forcefully against the United States' efforts to dilute the global action plan. We must be ambitious, because failure is not an option."

German Chancellor Angela Merkel, host of the G8 summit, has already dampened expectations of consensus.

"As the G8 we must come to a common understanding on how we can fight climate change. But as I stand here today, I am not sure that we will manage this in Heiligendamm," she said in the German parliament last week.

This week is a busy one on the environmental file. Federal and provincial environment ministers meet in Toronto on Monday, and will discuss the federal government's regulatory plan for greenhouse-gas reductions and how it will mesh with their own initiatives. On the same day, environmental groups will table their assessment of the government's plan. Baird appears before the House of Commons environment committee on Tuesday.