The climate impacts of oil sands are significant, and the greenhouse gas emissions for oil sands extraction and processing are significantly larger than for conventional crude oil. Using and extracting fossil fuels releases carbon dioxide and other greenhouse gases. There are two main components that make up the total released carbon dioxide, the first being the amount of CO2 released through the actual combustion and use of the fuel (in a vehicle, for example). For oil extracted in traditional methods and oil extracted from oil sands, this value is the same - 430 kilograms per barrel. Where the difference lies is in the amount of carbon dioxide released through the extraction, refining, and transport of the oil. Since bitumen from the oil sands is harder to extract and then must be upgraded into synthetic crudes that can be used, oil sands extraction releases comparatively more carbon dioxide into the atmosphere than traditional oil extraction.
In total, the production of a single barrel of synthetic crude oil from the oil sands releases around 134 kilograms of carbon dioxide. In contrast to these large emission values, average emissions per barrel of conventional crude oil are 35.2 kilograms of carbon dioxide in Canada and 24.5 kilograms in the US. The core difference in these emissions is a result of the extra upgrading that must be done to the crude bitumen extracted from the ground to obtain synthetic crude oils, a type of fuel that is "on par" with traditional crude oil. This upgrading process is energy-intensive. The released emissions including carbon dioxide contribute negatively to the effects of climate change and contribute to global warming overall, and contribute a more significant amount of these greenhouse gases than conventional oil does.
The graph below can be used to see the difference in emissions from synthetic crude oil and conventional crude oil. Although overall emissions are higher per barrel of synthetic crude oil from the oil sands, the largest portion of the emissions comes from the combustion and this value is the same for combustion of synthetic crude oil or traditional crude oil.