Transportation activities have a great impact on the environment because they fracture natural habitats and create pollution. Roads intrude into natural habitats, separating ecosystems and permanently altering the landscape. Road building has undesirable effects on species that require large tracts of undisturbed land. The main impact of transportation is due to vehicles large consumption of fossil fuels. This consumes the fossil fuel reserves, as well as releasing greenhouse gasses into the atmosphere. There is a radical difference between high road density in the settled parts of southern Canada, and virtually no roads in the Arctic ecosystems. The map shows the length of roads per ecoregion (in kilometres).