“Waste ponds can be seen at the Athabasca oil sands in Canada. The area contains the largest known deposits of bitumen on Earth. Bitumen is a semi-solid form of crude oil that naturally occurs as a mixture of sand, clay, and water. The additional energy required to mine and then remove the sand from the bitumen leads to the release of more carbon emissions than in any other form of oil production. Extraction takes place by injecting hot water into deep wells so the sands liquefy and can be pumped up to the surface. This waste pond is roughly four square miles (10 square kilometers).”