Oil is nasty stuff. When turned into gasoline or diesel and burned as fuel, it emits air pollution and carbon dioxide (a heat-trapping gas primarily responsible for global warming). But the extraction and refining processes that happen before you fill-up are, from a climate perspective, just as important—and they vary. Depending on where the oil is from, these “upstream” emissions can differ by a factor of 12, even though the final product—gasoline—appears the same.

Despite the climate implications, the oil industry does not disclose this type of information, and policy makers aren’t requiring it to do so. Fuel tracking policies that increase the transparency of the oil supply chain would help correct this, giving regulators the tools they need to assess the climate impacts of different oils.

As drivers switch to more-efficient vehicles and cleaner fuels, increased transparency will also help ensure that the oils we do use don’t get dirtier.

What is CO2e?

Extraction and refining oil to produce fuel can lead to different greenhouse gases being emitted. These gases (which include carbon dioxide, methane and nitrous oxide) each produce different amounts of warming. Because of this, scientists express the global warming potential of each greenhouse gas in terms of its carbon dioxide equivalent, or CO2e—the amount of carbon dioxide that would result in an equivalent amount of warming.

For this infographic, we used an average of the range of CO2e emissions associated with five different types of oil, as reported by the Carnegie Endowment for World Peace. Emissions are expressed in kilograms of CO2e per barrel of crude oil (“bbl crude”). One barrel of crude (42 gallons) typically results in just 19 gallons of gasoline and 12 gallons of diesel fuel.

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