Oil is one of the single largest drivers of climate change. Fossil fuels (coal, oil, and gas combined) account for nearly 90% of all carbon dioxide emissions and about 68% of total greenhouse gas emissions worldwide. Oil’s contribution runs deeper than just burning gasoline: it releases heat-trapping gases at every stage, from drilling to refining to the tailpipe, and triggers environmental feedback loops that accelerate warming further.
Why CO2 From Oil Traps Heat
When oil is burned in engines, furnaces, or power plants, the carbon locked inside it combines with oxygen to produce carbon dioxide. Once in the atmosphere, CO2 molecules do something that the nitrogen and oxygen making up most of our air cannot: they absorb infrared radiation, the heat energy that Earth’s surface radiates back toward space. A CO2 molecule captures that energy and vibrates, then either re-emits the heat in a random direction (often back toward the ground) or bumps into neighboring gas molecules, speeding them up. Faster-moving molecules mean higher temperatures. That is the greenhouse effect in its simplest form, and every barrel of oil burned adds to it.
Emissions at Every Stage of Production
Burning fuel in your car or heating your home is the most visible source of oil-related emissions, but the climate impact starts long before that. Extracting crude oil from underground requires energy-intensive drilling, pumping, and processing. Refining that crude into usable products like gasoline, diesel, and jet fuel adds roughly 14 to 72 kilograms of CO2-equivalent per barrel, with a global average around 41 kilograms per barrel. That refining step alone, applied to the roughly 100 million barrels the world processes daily, represents a massive emissions source before anyone fills a tank.
Then there’s flaring, the practice of burning off excess natural gas at oil wells when capturing it isn’t economical. Gas flaring released 350 million tonnes of CO2 globally in 2018. It’s essentially waste: energy burned for no productive purpose, heating the atmosphere as a byproduct of oil extraction.
Methane: Oil’s Other Greenhouse Gas
Carbon dioxide gets most of the attention, but methane leaking from oil and gas operations is a potent short-term warming agent. Methane traps far more heat per molecule than CO2 over a 20-year window, making even small leaks significant. A NOAA-funded study found that actual methane emissions from U.S. oil and gas operations between 2010 and 2019 were 70% higher than the Environmental Protection Agency had previously estimated.
There is a modest bright spot. Methane intensity, the ratio of methane leaked to methane produced, dropped from 3.7% in 2010 to 2.5% in 2019 in the U.S. If that trend continues, it could yield a 32% reduction in emissions by 2030. But the overall volume of methane released still grew during that period because oil and gas production itself increased so sharply.
Transportation: The Biggest Slice
Oil dominates the transportation sector like no other fuel. Cars, trucks, ships, and planes run overwhelmingly on petroleum products, and transport accounts for nearly one quarter of all global energy-related CO2 emissions. This is the sector where oil’s climate impact is most visible and most difficult to replace quickly, because vehicles last 10 to 15 years on the road, shipping infrastructure turns over slowly, and aviation has few viable alternatives to jet fuel at scale today.
Arctic Drilling and Permafrost Feedback Loops
Oil extraction in Arctic regions creates a particularly damaging feedback loop. Permafrost, the permanently frozen ground across northern Alaska, Canada, and Siberia, stores enormous quantities of organic carbon, some of it thousands of years old. When oil companies build drilling pads and infrastructure on this ground, the structures radiate heat into the surrounding soil. Research published in Scientific Reports documented localized warming and permafrost thaw expanding outward from oil well pads into the surrounding landscape.
As that frozen ground thaws, it releases stored carbon as CO2 and methane, which further warms the atmosphere, which accelerates more thawing. The secondary effects compound: increased water flow, surface warming, vegetation changes, and ongoing pollution. This isn’t a theoretical concern. All four study sites examined in the research showed measurable warming and thaw spreading laterally from drilling infrastructure into previously undisturbed permafrost.
How the Oceans Absorb the Cost
Natural systems partially buffer oil’s climate impact, but at a steep price. Plants and oceans together absorb roughly half of the CO2 that humans emit from fossil fuel burning. The ocean has been doing an outsized share of that work, and the chemistry of seawater is shifting as a result. Since the start of the Industrial Revolution, ocean surface pH has dropped from 8.21 to 8.10. That sounds small, but pH is a logarithmic scale: a 0.1-unit drop represents a 30% increase in acidity. This acidification threatens coral reefs, shellfish, and the marine food chains that billions of people depend on for protein.
The ocean’s role as a carbon sink also has limits. As water temperatures rise, seawater holds less dissolved gas, which means the ocean’s ability to keep absorbing CO2 at its current rate will likely diminish over time, leaving more emissions in the atmosphere.
What Cutting Oil Use Would Require
The International Energy Agency’s net-zero roadmap lays out stark numbers. To hold global warming to 1.5 degrees Celsius, oil consumption would need to fall by 75%, from around 90 million barrels per day in 2020 to 24 million barrels per day by 2050. That scale of reduction means electrifying most road transport, dramatically improving energy efficiency in industry and buildings, and finding alternatives for the hardest sectors to decarbonize, particularly aviation and petrochemicals.
The gap between current trajectory and that target is enormous. Global oil demand has continued rising in recent years, not falling. Every new oil well drilled locks in decades of future emissions, both from the fuel it produces and from the infrastructure built to support it. The climate math is straightforward: the carbon in oil stayed underground for millions of years, and burning it releases that stored carbon into an atmosphere that is already warmer than at any point in modern human history.