X-axis is the range of potential resource in billions of barrels. Y-axis is grams of Carbon per MegaJoule of final fuel.
The Canadian tar sands are substantially dirtier than conventional oil as the chart above shows (longer analysis here). They may contain enough carbon-intensive fuel to make stabilizing atmospheric concentrations of carbon dioxide at non-catastrophic levels all but impossible.
And that is the point of Dr. James Hansen in a must-read essay on the proposed Keystone XL Pipeline to bring that dirty fuel into this country, “Silence Is Deadly: I’m Speaking Out Against Canada-U.S. Tar Sands Pipeline.”
Hansen, director of NASA’s Goddard Institute for Space Studies, has been right longer about the climate than just about anyone else (see “Right for 27 years: 1981 Hansen study finds warming trend that could raise sea levels“). So he deserves to be heard.
Here is his essay, to which I’ve added some commentary with links: