An ecological catastrophe might be on the cards if a drive to get oil from unconventional fossil fuel sources continues, a report has warned.
With oil prices hitting record highs, the extraction of tar sands and oil shale is an increasingly attractive option.
But according to a study by WWF and the Co-operative Financial Services, the fuels are massively energy intensive - creating as much as eight times as many carbon emissions in their production as conventional oil.
If all the estimated 1,115 billion barrels of the recoverable fuels found in Canada and the US were to be extracted, the report estimates it would release 980 billion tonnes of CO2.
According to the study, the emissions could push atmospheric levels of CO2 well past the point at which it is estimated would trigger global temperature rises of more than 2C, causing dangerous climate change and putting the Earth at risk of mass extinction of species.
The researchers said oil giants including Shell and BP are planning to invest 125 billion Canadian dollars (£62 billion) in the fuels by 2015 and are intending to produce hundreds of thousands of barrels a day by 2020.
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