Canadian businessmen claim that by means of the Kyoto Protocol European Union tries to gain commercial advantage over other countries.
Canada's decision on ratification is expected to have a crucial effect on the long-term future of the United Nation's efforts to curb climate change even though its approval is not essential for the protocol to come into force.
The dispute has escalated since there was announced plans to put the protocol to a vote in parliament this year. There is an opinion that by this ratification European Union tries to gain commercial advantage over other countries.
The debate has been hampered by a lack of information about the costs of measures that would be required to implement the protocol, which requires Canada to cut its greenhouse gas emissions by 6 per cent from 1990 levels by 2008-2012.
A government assessment, prepared with the provinces and industry, concluded that by 2012, Kyoto might leave GDP unchanged or cut growth by as much as two percentage points. But it did not analyse the potential impact of the protocol on sales to the US, which buys most Canadian exports.
The paper also assumed Canada would get credits for clean energy exports, such as hydro-electricity, which displace dirtier fuels like coal. This proposal, which would require a reopening of negotiations on the Kyoto Protocol, has been flatly rejected by Margot Wallström, the EU's environment commissioner.
The paper also predicted that Canada would buy emission credits from Russia, a step that has been attacked by business representatives as a significant transfer of wealth for no return. These emission credits - which allow pollution allowances to be transferred - stem from the decline of Russia's industrial base since 1990, allowing it to overshoot its Kyoto targets.
Russia joined Canada at the Johannesburg summit in indicating it would ratify the protocol. Russia's participation is critical for the protocol to enter into force, which requires the ratification of countries representing 55 per cent of the industrialised world's emissions.
Canada does not emit enough greenhouse gases for its approval to have a decisive influence but a rejection would be significant because it would mean that there were no countries in the Americas taking on legally-binding emission targets.