Key points

• Crude oil production, refining, and combustion all produce heat and generate carbon dioxide (CO₂), a powerful greenhouse gas.

How much heat is generated from burning one barrel of crude oil? According to Statistics Canada¹, burning 1 barrel of crude oil = 6.193 gigajoules, or 0.6193 terajoules (TJ) of heat. For comparison’s sake, the Little Boy² atomic bomb dropped on Hiroshima released 62.8 to 66.9 ± 8.4 TJ—about 10,470 times more energy than is in a single barrel of oil.

In 2024 Alberta’s total GHG emissions were 260.1 MtCO₂e (260,100,000 tonnes). Oil sands (mining, in situ, upgrading) was 32.73% of that, oil and gas transmission and refining was 4.19%, and conventional oil production was 7.08%³, so (leaving out natural gas production and processing at 15.05%) 44% of Alberta’s GHG emissions in 2024 were from oil (114,444,000 tons of CO₂).

In 2024 Alberta produced an average of 3.98 million barrels per day, or 1453.695 million per year. We can therefore deduce that for Alberta crude oil production, one tonne of CO₂ is released in the generation of 12.7022 barrels of oil (1,453,695,000 barrels / 114,444,000 tons of CO₂). This is an impressive figure, if accurate: I’ve seen estimates that are several times higher. But let’s use the official Alberta government figures.
• N.B.: The radiative forcing caused by greenhouse gases released from oil production, refining, and combustion equals the heat that came from these activities very quickly: after only about 45 days.

According to “Time scales and ratios of climate forcing due to thermal versus carbon dioxide emissions from fossil fuels” ⁴ by Xiaochun Zhang and Ken Caldeira, the radiative forcing from released CO₂ exceeds the amount of heat generated by burning oil after about 45 days, and about 34 days for coal, and about 59 days for methane (natural gas).

This datum is key to understanding the rate and scale of anthropogenic global heating.
• Only a small amount of those greenhouse gases are quickly absorbed by plants or the ocean; the rest stays in the atmosphere for a long time.

The Bern Simple Climate Model (BernSCM) v1.0⁵ published by the European Geosciences Union Geoscientific Model Development (Articles, Volume 11, Issue 5, 25 May 2018) describes types of carbon sequestration that operate at different time scales:

• plants and upper ocean (years to decades),
• deep ocean (centuries), and
• geological processes (millennia).

Using a Pulse Response Model, these three significant processes get summed to provide the annual amount of carbon sequestered from a pulse of CO₂ released into the atmosphere. Unfortunately, all three are two-way processes—not so much “sinks” as “banks”.

• When a plant grows it absorbs CO₂, but when it dies it releases CO₂.
• The upper ocean absorbs CO₂ (and becomes more acidic, but that’s a different problem), but depending upon the partial pressure, will release that CO₂.
• The deep ocean only absorbs CO₂ if and when the thermohaline circulation is effective, such as that driving the AMOC (Atlantic Meridional Overturning Circulation), and that’s becoming less effective as surface water becomes less salty due to melting ice caps.
• Even the rocks may be two-way streets for CO₂: a recent paper in Nature⁶ reports that rock organic carbon oxidation CO₂ release offsets the silicate weathering sink, rivalling or even exceeding the CO₂ drawdown by silicate weathering at the global scale. Therefore, the geological component of the Pulse Response Model may be functionally zero, at least on human timescales.

Therefore, the naïve notion that CO₂ is quickly and permanently absorbed by growing plants does not accurately or adequately explain what we’re seeing, which is a continuous and accelerating buildup of CO₂ ever since we first began to measure it. Some of what we put into the air now is still going to be there in thousands of years, and is going to be duplicating the heat from combustion every 45 days. Nevertheless, some CO₂ is indeed absorbed, so once we estimate the annual reduction of CO₂, we can derive a matching reduction in radiative forcing due to that CO₂.
• Since we know how much heat is generated by burning a barrel of crude oil, if we also know how much CO₂ is released in the process, we can model how much CO₂ is absorbed over time, and how much remains to continue to trap infrared radiation and heat the planet.

How much CO₂ is released per barrel burned? Envorem Calculations And Sources Used Across Our Site says that 2.79 mass units (e.g. kilograms) of CO₂ are generated per mass unit of oil burned, although I’ve seen higher figures such as 3.15. And What Is a Barrel of Oil Weight and Why Does It Matter in Industrial Applications? says that a barrel of crude oil masses between 136 and 143 kilograms. Therefore, I deduce that between 379.44 and 399 kg of CO₂ is released per barrel burned (or using the 3.15 ratio, 428.4 to 450.45 kg of CO₂). The extra mass in the CO₂ comes from the oxygen in the air.

Having a ratio between CO₂ released from crude oil production and CO₂ released from crude oil combustion allows us to infer the ratio between the produced heat and the burned heat.

We also have data about the effects of refining. The Union of Concerned Scientists reports that “a typical oil refinery in the United States consumes between 540 and 690 MJ and emits between 97 and 111 lbs of CO₂ per barrel of crude oil refined.”⁷ Therefore, we can similarly deduce a ratio between the heat from refining and the heat from combustion.
• Therefore, we can calculate the actual amount of global heating due to radiative forcing caused by greenhouse gases emitted from a specific number of barrels of crude oil over a long time period. This is its “carbon legacy”.

I don’t think “carbon footprint” is an appropriate term for what we’re discussing here. You use “carbon footprint” to estimate your current consumption of resources, but the CO₂ left in the atmosphere is your “carbon legacy”—what you leave for posterity.

Alberta current produces over four million barrels of crude oil per day, or almost 1.5 billion barrels per year. To a first approximation, multiply the heat generated by burning oil by 8 to get the amount of heat generated annually from the CO₂ released by burning. This ratio goes down as CO₂ is absorbed, but this is not a quick process.

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• Applying this calculation to current and planned oil production from Alberta’s oil sands reveals interesting results.

In 2026 Prime Minister Carney and Premier Danielle Smith announced plans for a new pipeline to transport a million barrels per day of crude oil from the Alberta oil sands to a deep-water Pacific port in British Columbia. Furthermore, the Alberta government has announced its intent by 2035 to increase production to 8 million barrels of oil per day ⁸ despite the fact that the Alberta oil sands are among the most carbon-intensive sources of crude oil in North America⁹.

Alberta, along with the Canadian federal goverment, has announced a plan to reduce the carbon dioxide emitted during production. The Pathways Project¹⁰ aims to keep 16 million tons of CO₂ out of the atmosphere every year, reducing the emissions from the production process. However, this would only handle about 1% of the total emissions from producing, refining, and burning 8 million barrels of oil - it’s a bandaid on a gaping wound, and uses unproven technology in any case. Carbon sequestration projects have a habit of over-promising and under-performing, especially when required to scale up to meaningful results.¹¹

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