Buried just beneath a layer of muskeg and forest in northern Alberta, Canada, lies a 50,000 square mile reservoir of heavy crude oil, possibly holding 2 trillion barrels of recoverable oil. These bitumen deposits require a lot of effort to extract, recover, and pre-process before the oil can be sent to conventional refineries. Most of the current extraction process takes place in open-pit mines, with massive machinery scraping up the tarry sandstone and moving it to facilities for processing. As the name "tar sands", or oil sands, implies, the heavy crude is found mixed in with sand, clay, and water, which must be removed, then the heavy crude must be "upgraded" to reduce viscosity and improve quality. Environmental activists have expressed concerns about the mining for years, citing destructive impacts on the land, the heavy carbon footprint of the laborious extraction and upgrade process, massive amounts of toxic byproducts, and studies that show oil sands crude emits more greenhouse gases than conventional crude oil. Oil companies continue to make efforts to reduce carbon emissions, manage toxic byproducts, and reclaim mined land, while ramping up production. The Alberta tar sands are currently producing around two million barrels of oil per day, with plans to increase that to nearly four million barrels per day by 2022. Reuters photographer Todd Korol recently traveled to Alberta to photograph some of the mines, facilities, and surrounding landscape.