Yale Environment 360: These satellite images, taken from July 1984 through May 2011, reveal the development of the Athabasca oil sands, commonly called "tar sands," which lie at the heart of Albertas oil deposits. Tar sands mining, which has become a significant issue for environmentalists, has been rapid and extensive, growing to cover nearly 260 square miles of the Canadian province by 2011. It has also proven lucrative for Alberta: Nearly 2 million barrels of oil are produced every day, according to the provincial...