Energy systems
Fossil Fuels
Carbon-rich fuels formed from the remains of ancient organisms — coal, petroleum, and natural gas — that supply most of the world's energy and most of its greenhouse gas emissions.
Definition
Fossil fuels are hydrocarbon-containing materials of biological origin, formed from the buried remains of plants and animals over geological time, that are burned to release energy. The category includes coal, petroleum and its refined products, and natural gas, along with derivatives such as oil shales, bitumens, tar sands, and heavy oils. They are non-renewable resources.
References
definition and energy share
Overview
What it means
Fossil fuels powered industrialisation and still supply more than 80% of energy in industrialised countries, but their combustion is the dominant source of anthropogenic carbon dioxide and a major source of air pollution. Their geological origin means reserves are finite and unevenly distributed, shaping global trade and geopolitics.
How it is used
The term frames the central divide in energy policy between conventional and renewable sources; it appears throughout climate negotiations, national energy statistics, and decarbonisation planning.
Why it matters
Understanding what counts as a fossil fuel — and what "unabated" use means — is a prerequisite for reading phase-out commitments, carbon budgets, and energy-transition scenarios.
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