As the Copenhagen climate-change summit approaches, environmental activists are stepping up their attacks on the vast Alberta oil sands as a prime example of the world’s dependence on “dirty” energy.

Greenpeace protestors have driven home their message in recent weeks by disrupting operations at Royal Dutch Shell and Suncor projects. Others entered a Total refinery in Normandy, France, to protest against that company’s investments in the oil sands, and defaced Total billboards around Edmonton, the Alberta capital, accusing it of "environmental destruction".