A new report highlighting the environmental ramifications of approving the Keystone XL Pipeline.
Washington's Congressional Research Service holds oil sands crude is 20 to 40 per cent more emissions intensive than conventionally derived fuels.
Analysts say the TransCanada project, and the resulting industry expansion, could cause the country's carbon emissions to spike by as much as 21 million metric tonnes, each year.
Citing environmental concerns, American President Barack Obama rejected the $ 7.6 billion Alberta to Texas oil sands link earlier this year.
The contraversial oil sands link would transport 830,000 barrels of crude per day.