Petroleum damages the environment at every stage of its lifecycle, from extraction and refining to combustion and disposal. Its effects span the atmosphere, oceans, soil, drinking water, and wildlife habitats. The energy sector, dominated by fossil fuels like petroleum, accounts for 75.7% of global greenhouse gas emissions, making oil one of the single largest drivers of environmental harm on the planet.
Air Pollution and Climate Change
Burning petroleum for transportation, heating, and electricity is one of the primary sources of carbon dioxide in the atmosphere. CO₂ makes up about 74% of all greenhouse gas emissions, and 92% of that comes from fossil fuel use. Transportation alone contributes 13.3% of global CO₂ emissions, with road vehicles responsible for most of that share. Since 1990, total global greenhouse gas emissions have grown by 51%.
Beyond combustion, the oil and gas industry itself is a major emitter. The production, transport, and processing of oil and gas released 5.1 billion tonnes of greenhouse gas emissions in 2022, accounting for roughly 15% of all energy-related emissions worldwide. That figure includes methane vented and flared during extraction, which adds potent short-term warming on top of the CO₂ released when the fuel is eventually burned.
Refineries also release hazardous air pollutants. The EPA has estimated that its regulations on petroleum refineries reduce emissions of eleven toxic compounds, including benzene (a known human carcinogen), by 53,000 tons per year. These pollutants are linked to cancer, reproductive harm, and birth defects in nearby communities.
Oil Spills and Ocean Contamination
Oil enters the ocean through tanker accidents, pipeline leaks, offshore drilling blowouts, and routine operational discharges. In 2024, approximately 10,000 tonnes of oil were lost to the environment from tanker spills alone, across six large spills and four medium-sized incidents. While that figure is far lower than the catastrophic spill years of the 1970s and 1980s, the damage from each event is severe and long-lasting.
Crude oil harms marine life through several pathways: direct poisoning, disruption of normal behavior and reproduction, physical coating of feathers and fur, absorption of toxic compounds into tissues, and destruction of habitat. The toxic components dissolved in seawater, particularly a class of compounds called PAHs, can poison fish embryos without the oil ever physically touching them. Embryos exposed to dissolved petroleum compounds develop edema, hemorrhaging, and heart abnormalities in a dose-dependent pattern, meaning even small concentrations cause measurable harm. Sub-lethal effects on marine organisms can begin at concentrations as low as 10 to 100 parts per billion.
For marine mammals and seabirds, oil coating is often fatal. It destroys the insulating properties of fur and feathers, leading to hypothermia, and animals that ingest oil while grooming suffer internal organ damage.
Noise Pollution From Exploration
Before oil is even extracted, the search for it causes environmental harm. Seismic surveys use powerful airguns to map underground rock formations, and the noise they produce blankets areas of up to 300,000 square kilometers. These sounds have been recorded as far as 4,000 kilometers from the source, traveling especially well in deep water.
This is a serious problem for species that rely on sound to navigate, communicate, and find mates. Off the coast of northern Angola, seismic surveys have been shown to disrupt humpback whale singing activity. The frequency range of airgun blasts overlaps with the hearing range of most fish and sharks, and can trigger neurological responses in squid and crustaceans. For animals that depend on a relatively quiet ocean to survive, industrial noise pollution is an invisible but widespread threat.
Soil Contamination
When petroleum leaks from pipelines, storage tanks, or drilling sites, it saturates the surrounding soil and disrupts the microbial ecosystems that keep it healthy. Research published in the journal Environmental Science and Pollution Research found that heavy petroleum contamination (above 20,000 milligrams per kilogram of soil) significantly reduces microbial diversity and degrades the soil’s ability to cycle carbon and nitrogen. These are fundamental biological processes: nitrogen-fixing bacteria help plants grow, and carbon cycling keeps soil fertile. At high contamination levels, the genes responsible for these functions become measurably less active.
Moderate contamination, between 4,000 and 20,000 mg/kg, is less destructive but still reshapes microbial communities in ways that alter how the ecosystem functions. The practical result is soil that can’t support the same plant life it once did, which cascades into effects on insects, birds, and other animals that depend on that vegetation.
Groundwater and Drinking Water
Petroleum contamination reaches groundwater primarily through leaking underground storage tanks, spills at fueling stations, and runoff from industrial sites. The compounds of greatest concern are benzene, toluene, and xylenes, collectively known as BTEX. These chemicals dissolve in water and travel through soil into aquifers.
Acute exposure causes skin irritation, respiratory problems, and central nervous system effects. Chronic exposure damages the kidneys, liver, and blood. Benzene is the most dangerous of the group. Workers exposed to high levels have shown increased rates of leukemia, and the EPA classifies it as a confirmed human carcinogen. The maximum allowable level of benzene in public drinking water is just 0.005 parts per million, set so that a lifetime of exposure at that concentration would cause no more than one to one hundred additional cancer cases per million people. Toluene and xylenes are permitted at higher levels (1 ppm and 10 ppm respectively) because their cancer risk is lower, though they still cause organ damage over time.
Plastic Pollution
Petroleum’s environmental footprint extends well beyond fuel. About 98% of single-use plastic is made from petrochemicals derived from oil and gas. Once produced, roughly 22% of all plastic waste ends up in the environment rather than being recycled or properly disposed of. Much of it reaches the ocean, where it breaks down into microplastics that enter the food chain, from plankton to fish to the seafood on your plate.
Plastic production is also energy-intensive, generating emissions at the refinery stage and during manufacturing. As global plastic output continues to rise, this represents a growing share of petroleum’s total environmental impact, one that persists for hundreds of years after the product is discarded.
How Contaminated Sites Get Cleaned Up
Restoring petroleum-contaminated environments is slow and expensive, but biological approaches have shown real promise. Certain bacteria can consume petroleum hydrocarbons as their sole food source, breaking them down into less harmful compounds. In lab conditions, one bacterial strain (Rhodococcus hoagii) degraded 87% of petroleum hydrocarbons within just 24 hours, an unusually fast rate. Other strains achieved between 23% and 96% reduction within 48 hours.
Plants also play a role. Switchgrass, for example, has been shown to remove 37% of certain petroleum compounds from contaminated soil, converting most of it into CO₂ and incorporating a small fraction into plant tissue. In practice, bioremediation works best in warm conditions and takes months to years at a real spill site, far slower than lab results suggest. Cold environments, deep contamination, and heavy crude oil all reduce effectiveness. Still, biological cleanup remains one of the most practical tools for sites where simply digging up contaminated soil isn’t feasible.