Transportation fuels produced solely from oil sands result in well-to-wheels life-cycle greenhouse gas (GHG) emissions 5 to 15 percent higher than the average crude refined in the United States. Well-to-wheels emissions include those produced during crude oil extraction, processing, distribution, and combustion in an engine. Many analyses of oil sands GHG emissions focus on emissions in the extraction through refining phases, also known as the well-to-retail pump portion of the life cycle. However, 70 to 80 percent of GHG emissions for all sources of crude oil, including oil sands, occur at the combustion phase. combustion emissions do not vary for a given fuel among sources of crude oil. oil suppliers influence only the well-to-retail pump emissions, which account for 20 to 30 percent of total life-cycle GHG emissions.