Canada has officially ratified the Kyoto Protocol on greenhouse gases. Prime Minister Jean Chrétien signed the document at a ceremony at his office Monday afternoon.

"Because we believe in international institutions, we believed that we could play a positive role," he told a beaming Environment Minister David Anderson after signing the document. "This is very important for future generations."

Anderson will fly to New York Tuesday to present the document to the United Nations.

Under the accord, Canada has until 2012 to lower its greenhouse gas emissions to six per cent below what they were in 1990.

That would require a cut of 20 to 30 per cent from current levels.

Parliament ratified the treaty in a largely symbolic vote last Tuesday.

Alberta, oil interests opposed

Monday's signing ceremony comes after months of debate.

Critics, led by members of the petroleum industry and the Alberta government, complained that the accord will cost the Canadian economy billions of dollars.

But Chrétien said he believes Canadian individuals and businesses will support the effort to reduce the production of greenhouse gases implicated in global warming.

"We have 10 years to solve the problems now," he told reporters.

He said negotiations are already under way with some of the heaviest polluters and that he's confident that an agreement can be reached.

More than 160 countries negotiated the international agreement in 1997 in Kyoto, Japan.

In order to take effect, it must be ratified by enough countries to account for 55 per cent of emissions covered by the protocol.

More than 95 countries have ratified so far, including the entire European Union, Japan, Norway and New Zealand.

Russia's ratification, which is expected soon, is still needed to reach the 55 per cent emissions level.