…[I]n the northern part of [Alberta, Canada] there are vast deposits of bitumen - black, tarlike goo that is mixed up with sand, clay, water and oil…It is possible to turn Alberta's crud into crude, but it's awfully hard…Until quite recently, that made no economic sense…All the majors, save BP, have rushed to northern Alberta: ExxonMobil, Chevron and Total…And that's the Alberta tar sands for you: the industry already contributing to climate change more than any other is frantically turning up the heat. The process of refining bitumen emits three to four times the greenhouse gases produced by extracting oil from traditional wells…[also refers to Shell]