A trillion dollars’ worth of heavy crude oil has attracted the world’s oil titans to western Canada — and they’re making a mess. The World and GlobalPost’s GroundTruth Project head to the skies for a look at the sweeping impact of oil extraction from the Alberta Tar Sands.A trillion dollars’ worth of heavy crude oil has attracted the world’s oil titans to western Canada — and they’re making a mess. The World and GlobalPost’s GroundTruth Project head to the skies for a look at the sweeping impact of oil extraction from the Alberta Tar Sands.