For their calculations, the two assumed that where there was a gap between demand and conventional supply it would be filled with synthetic fuels, first with tar-sands oil and later with oil from coal and shale. (According to high-end estimates, coal and oil shale could together yield some ten trillion barrels of unconventional crude.) They then calculated what the impact would be on global carbon-dioxide levels.

NEWYORKER: Unconventional Crude

The greens may not be able to stop the Canadians from extracting oil from the Alberta tar sands, but they would succeed in wiping out American coal-fired power.

WSJ: Review & Outlook: Carbon Power Politics