The emerging global shift from light oil to heavy oil will bring with it new chain of environmental threats in terms of increasing emissions of carbon dioxide, severe degradation of surface water and ground-water qualities as well as damage to aquatic life and bio-diversity.

The so-called Tar Sand (http://sv.m.wikipedia.org/wiki/Oljesand) has severe negative impacts on  climate, natural water quality and aquatic life if protection and conservation strategies are not properly implemented in association with mining and processing.

http://www.livescience.com/49004-environmentalists-fear-tar-sands-lake-toxicity-lobbyist-video.html