How the oil sands could very quickly become unviable

It was reported today that Exxon-Mobil will begin disclosing the degree to which its assets are exposed to future greenhouse gas policies. This risk is at the heart of what has become known as the carbon bubble, a term advanced by UK group Carbon Tracker, which suggests that assets may be over-valued as a result of not accounting for potential future limits on fossil fuel extraction imposed to fight climate change.