Canadian tar sands could quench U.S. thirst.

• Position: Oil Reserves

Canadian tar sands deposits hold an estimated 1.7 trillion barrels of crude oil, second in the world only to Saudi Arabia, but the environmental impact of mining them far exceeds that of conventional oil, writes Dan Woynillowicz for the Woddwatch Institute, Washington, D.C.

The energy-intensive process of extracting crude bitumen from the mixture of sand, clay, and silt releases up to three times more greenhouse gas pollution than conventional oil extraction and wreaks havoc on local forests, wildlife, fresh water resources, and air quality, Woynillowicz maintains. "Everything about the tar sands is big, most significantly its global warming and environmental implications--leading some to now describe the tar sands as 'Canada's dirty secret.'"

The tar sands deposits underlie more than 140,000 square kilometers of relatively pristine boreal forest, which accounts for one-quarter of the world's remaining intact woodlands. If currently planned development projects go forward, approximately 3,000 square kilometers of forest could be cleared, drained, and strip-mined. The remaining forest stands to be compromised by the extraction process used for deeper reserves, which...