Conventional oil and gas production: Impact on the biosphere

Blowouts, spills, flaring and a huge methane leak

What this tab covers Effects on human, animal, plant, fungal and microbial life and on whole ecosystems: in the short term (construction and early years), medium term (operating life) and long term (decommissioning and legacy).

Producing oil and gas causes local harm from spills, flaring and habitat disturbance, a large methane burden, and, once the fuels are burned, heavy air pollution and climate change. Large offshore blowouts are rare but severe.

Deaths per TWh, oil (accidents and air pollution) 18.43¹¹ Deaths per TWh, gas (accidents and air pollution) 2.82¹¹ Upstream carbon intensity of crude (world average, 2015) 10.3 g CO2e per MJ⁸ Methane from oil and gas operations (2025) 81 Mt (45 oil plus 36 gas, calculated)⁹ Largest spills Ixtoc I 3.5 million barrels (1979); Deepwater Horizon 4.9 million barrels (2010)⁶

Effects over time

Life affected	Short term	Medium term	Long term
Humans¹²¹¹	Blowouts and fires: 11 workers died on Deepwater Horizon (2010)	Air pollution from the oil chain: 18.43 deaths per TWh; gas 2.82	Climate change from combustion and methane
Animals⁶¹²	Oil coating and ingestion harm seabirds, sea turtles, marine mammals and fish	Ecosystems may recover within 2 to 10 years of a spill, even after heavy mortality	Little evidence of effect quantified in our sources
Plants⁶	Vegetation cleared for well pads, roads and pipeline routes (area not quantified in our sources)	Little evidence of effect quantified in our sources	Little evidence of effect
Fungi and soil life⁶	Little evidence of effect	Little evidence of effect	Little evidence of effect
Ecosystems⁶¹²⁹	Deepwater Horizon released 4.9 million barrels (134 million gallons) over 87 days	Methane from oil operations 45 Mt and gas 36 Mt a year (2025)	Leaking decommissioned pipelines and wells remain a risk

How the effects are reduced

Blowout preventers, well-integrity rules and spill response planning reduce the risk of large spills. Ending routine flaring and fixing leaks are the cheapest climate measures: nearly 30 Mt of upstream oil and gas methane could be abated at no net cost at 2025 prices. Electrifying platforms from shore cuts on-site combustion. Proper plugging of old wells and removal of offshore structures limits legacy leaks.

Sources

Third World Ocean Assessment, Chapter 3, Subchapter 3b: Offshore hydrocarbons United Nations, 2025
Global carbon intensity of crude oil production (Masnadi et al., Science 361(6405): 851-853) Science (AAAS), 2018
Global Methane Tracker 2026: Key findings International Energy Agency, 2026
What are the safest and cleanest sources of energy? Our World in Data, 2024
10 Years After Deepwater Horizon, We're Optimistic About the Future NOAA Fisheries, 2020