A fossil fuel is a
hydrocarbon-containing material formed naturally in the
Earth's crust
Earth's crust is Earth's thin outer shell of rock, referring to less than 1% of Earth's radius and volume. It is the top component of the lithosphere, a division of Earth's layers that includes the crust and the upper part of the mantle. The ...
from the remains of dead plants and animals that is extracted and
burned
Burned or burnt may refer to:
* Anything which has undergone combustion
* Burned (image), quality of an image transformed with loss of detail in all portions lighter than some limit, and/or those darker than some limit
* ''Burnt'' (film), a 2015 ...
as a
fuel
A fuel is any material that can be made to react with other substances so that it releases energy as thermal energy or to be used for work. The concept was originally applied solely to those materials capable of releasing chemical energy but ...
. The main fossil fuels are
coal,
oil, and
natural gas. Fossil fuels may be burned to provide heat for use directly (such as for cooking or heating), to power engines (such as
internal combustion engines in motor vehicles), or to
generate electricity. Some fossil fuels are refined into derivatives such as
kerosene,
gasoline and
propane
Propane () is a three-carbon alkane with the molecular formula . It is a gas at standard temperature and pressure, but compressible to a transportable liquid. A by-product of natural gas processing and petroleum refining, it is commonly used a ...
before burning. The origin of fossil fuels is the
anaerobic decomposition of buried dead
organisms, containing
organic molecules
In chemistry, organic compounds are generally any chemical compounds that contain carbon-hydrogen or carbon-carbon bonds. Due to carbon's ability to catenate (form chains with other carbon atoms), millions of organic compounds are known. The s ...
created by
photosynthesis.
The conversion from these materials to high-carbon fossil fuels typically require a geological process of millions of years.
In 2019, 84% of
primary energy consumption in the world and 64% of its electricity was from fossil fuels. The large-scale burning of fossil fuels causes serious
environmental damage. Over 80% of the
carbon dioxide (CO
2) generated by human activity comes from burning them: around 35 billion
tonnes a year, compared to 4 billion from
land development
Land development is the alteration of landscape in any number of ways such as:
* Changing landforms from a natural or semi-natural state for a purpose such as agriculture or housing
* Subdividing real estate into lots, typically for the purpose ...
.
Natural processes on Earth, mostly
absorption by the ocean, can only remove a small part of this. Therefore, there is a net increase of many billion tonnes of atmospheric carbon dioxide per year. Although
methane leaks are significant, the burning of fossil fuels is the main source of
greenhouse gas
A greenhouse gas (GHG or GhG) is a gas that Absorption (electromagnetic radiation), absorbs and Emission (electromagnetic radiation), emits radiant energy within the thermal infrared range, causing the greenhouse effect. The primary greenhouse ...
emissions causing
global warming and
ocean acidification. Additionally, most air pollution deaths are due to fossil fuel
particulates and noxious gases. It is estimated that this costs over 3% of the global
gross domestic product and that
fossil fuel phase-out
Fossil fuel phase-out is the gradual reduction of the use and production of fossil fuels to zero.
It is part of the ongoing renewable energy transition. Current efforts in fossil fuel phase-out involve replacing fossil fuels with sustainab ...
would save millions of lives each year.
Recognition of the
climate crisis,
pollution and other negative impacts caused by fossil fuels has led to a widespread
policy transition and
activist movement focused on ending their use in favor of
sustainable energy
Energy is sustainable if it "meets the needs of the present without compromising the ability of future generations to meet their own needs". Most definitions of sustainable energy include considerations of environmental aspects such as greenh ...
. However, because the
fossil-fuel industry
A fossil fuel is a hydrocarbon-containing material formed naturally in the Earth's crust from the remains of dead plants and animals that is extracted and burned as a fuel. The main fossil fuels are coal, oil, and natural gas. Fossil fuels may ...
is so heavily integrated in the global economy and
heavily subsidized, this transition is expected to have significant economic impacts. Many stakeholders argue that this change needs to be a
just transition
Just transition is a framework developed by the trade union movement to encompass a range of social interventions needed to secure workers' rights and livelihoods when economies are shifting to sustainable production, primarily combating climat ...
and create policy that addresses the societal burdens created by the
stranded assets of the fossil fuel industry.
International policy, in the form of United Nations sustainable development goals for
affordable and clean energy and
climate action
Climate change mitigation is action to limit climate change by reducing emissions of greenhouse gases or removing those gases from the atmosphere. The recent rise in global average temperature is mostly caused by emissions from fossil fuels b ...
, as well as the
Paris Climate Agreement, is designed to facilitate this transition at a global level. In 2021, the
International Energy Agency
The International Energy Agency (IEA) is a Paris-based autonomous intergovernmental organisation, established in 1974, that provides policy recommendations, analysis and data on the entire global energy sector, with a recent focus on curbing carb ...
concluded that no new
fossil fuel extraction projects could be opened if the global economy and society wants to avoid the worst
impacts of climate change
The effects of climate change impact the physical environment, ecosystems and human societies. The environmental effects of climate change are broad and far-reaching. They affect the water cycle, oceans, sea and land ice (glaciers), sea leve ...
and meet international goals for
climate change mitigation
Climate change mitigation is action to limit climate change by reducing Greenhouse gas emissions, emissions of greenhouse gases or Carbon sink, removing those gases from the atmosphere. The recent rise in global average temperature is mostly caus ...
.
Origin

The theory that fossil fuels formed from the
fossilized remains of dead plants by exposure to heat and pressure in
Earth's crust
Earth's crust is Earth's thin outer shell of rock, referring to less than 1% of Earth's radius and volume. It is the top component of the lithosphere, a division of Earth's layers that includes the crust and the upper part of the mantle. The ...
over millions of years was first introduced by
Andreas Libavius "in his 1597 Alchemia
lchymia and later by
Mikhail Lomonosov
Mikhail Vasilyevich Lomonosov (; russian: Михаил (Михайло) Васильевич Ломоносов, p=mʲɪxɐˈil vɐˈsʲilʲjɪvʲɪtɕ , a=Ru-Mikhail Vasilyevich Lomonosov.ogg; – ) was a Russian Empire, Russian polymath, s ...
"as early as 1757 and certainly by 1763". The first use of the term "fossil fuel" occurs in the work of the German chemist
Caspar Neumann, in English translation in 1759.
The ''
Oxford English Dictionary'' notes that in the phrase "fossil fuel" the adjective "fossil" means "
tained by digging; found buried in the earth", which dates to at least 1652, before the English noun "fossil" came to refer primarily to long-dead organisms in the early 18th century.
Aquatic
phytoplankton
Phytoplankton () are the autotrophic (self-feeding) components of the plankton community and a key part of ocean and freshwater ecosystems. The name comes from the Greek words (), meaning 'plant', and (), meaning 'wanderer' or 'drifter'.
Ph ...
and
zooplankton that died and sedimented in large quantities under
anoxic conditions millions of years ago began forming petroleum and natural gas as a result of
anaerobic decomposition. Over
geological time
The geologic time scale, or geological time scale, (GTS) is a representation of time based on the rock record of Earth. It is a system of chronological dating that uses chronostratigraphy (the process of relating strata to time) and geochronol ...
this
organic
Organic may refer to:
* Organic, of or relating to an organism, a living entity
* Organic, of or relating to an anatomical organ
Chemistry
* Organic matter, matter that has come from a once-living organism, is capable of decay or is the product ...
matter, mixed with
mud
A MUD (; originally multi-user dungeon, with later variants multi-user dimension and multi-user domain) is a Multiplayer video game, multiplayer Time-keeping systems in games#Real-time, real-time virtual world, usually Text-based game, text-bas ...
, became buried under further heavy layers of inorganic sediment. The resulting high temperature and
pressure caused the organic matter to chemically
alter
Alter may refer to:
* Alter (name), people named Alter
* Alter (automobile)
* Alter (crater), a lunar crater
* Alter Channel, a Greek TV channel
* Archbishop Alter High School, a Roman Catholic high school in Kettering, Ohio
* ALTER, a comman ...
, first into a waxy material known as
kerogen, which is found in
oil shales, and then with more heat into liquid and gaseous hydrocarbons in a process known as
catagenesis. Despite these heat-driven transformations, the energy released in combustion is still photosynthetic in origin.
Terrestrial plants tended to form coal and methane. Many of the coal fields date to the
Carboniferous
The Carboniferous ( ) is a geologic period and system of the Paleozoic that spans 60 million years from the end of the Devonian Period million years ago ( Mya), to the beginning of the Permian Period, million years ago. The name ''Carbonifero ...
period of
Earth's history. Terrestrial plants also form
type III kerogen
Type may refer to:
Science and technology Computing
* Typing, producing text via a keyboard, typewriter, etc.
* Data type, collection of values used for computations.
* File type
* TYPE (DOS command), a command to display contents of a file.
* ...
, a source of natural gas. Although fossil fuels are continually formed by natural processes, they are classified as
non-renewable resources because they take millions of years to form and known viable reserves are being depleted much faster than new ones are generated.
Importance

Fossil fuels have been important to human development because they can be readily burned in the open atmosphere to produce heat. The use of
peat as a domestic fuel predates recorded history. Coal was burned in some early furnaces for the
smelting of
metal ore, while semi-solid hydrocarbons from oil seeps were also burned in ancient times, they were mostly used for waterproofing and
embalming.
Commercial exploitation of petroleum began in the 19th century.
Natural gas, once
flared-off as an unneeded byproduct of petroleum production, is now considered a very valuable resource. Natural gas deposits are also the main source of
helium.
Heavy crude oil, which is much more viscous than conventional crude oil, and
oil sands, where
bitumen
Asphalt, also known as bitumen (, ), is a sticky, black, highly viscous liquid or semi-solid form of petroleum. It may be found in natural deposits or may be a refined product, and is classed as a pitch. Before the 20th century, the term a ...
is found mixed with sand and clay, began to become more important as sources of fossil fuel in the early 2000s. Oil shale and similar materials are
sedimentary rocks containing
kerogen, a complex mixture of high-molecular weight organic compounds, which yield
synthetic crude oil when heated (
pyrolyzed
The pyrolysis (or devolatilization) process is the thermal decomposition of materials at elevated temperatures, often in an inert atmosphere. It involves a change of chemical composition. The word is coined from the Greek-derived elements ''pyr ...
). With additional processing, they can be employed instead of other established fossil fuels. During the 2010s and 2020s there was
disinvestment
Disinvestment refers to the use of a concerted economic boycott to pressure a government, industry, or company towards a change in policy, or in the case of governments, even regime change. The term was first used in the 1980s, most commonly in ...
from exploitation of such resources due to their high
carbon cost relative to more easily-processed reserves.
Prior to the latter half of the 18th century,
windmills and
watermills provided the energy needed for work such as milling flour,
sawing wood or pumping water, while burning wood or
peat provided domestic heat. The wide-scale use of fossil fuels, coal at first and petroleum later, in
steam engine
A steam engine is a heat engine that performs mechanical work using steam as its working fluid. The steam engine uses the force produced by steam pressure to push a piston back and forth inside a cylinder. This pushing force can be trans ...
s enabled the
Industrial Revolution. At the same time,
gas lights using natural gas or
coal gas
Coal gas is a flammable gaseous fuel made from coal and supplied to the user via a piped distribution system. It is produced when coal is heated strongly in the absence of air. Town gas is a more general term referring to manufactured gaseous ...
were coming into wide use. The invention of the
internal combustion engine and its use in
automobiles and trucks greatly increased the demand for gasoline and
diesel oil, both made from fossil fuels. Other forms of transportation, railways and aircraft, also require fossil fuels. The other major use for fossil fuels is in
generating electricity and as
feedstock
A raw material, also known as a feedstock, unprocessed material, or primary commodity, is a basic material that is used to produce goods, finished goods, energy, or intermediate materials that are feedstock for future finished products. As feedst ...
for the
petrochemical industry.
Tar, a leftover of petroleum extraction, is used in the
construction of roads.
The energy for the
Green Revolution was provided by fossil fuels in the form of
fertilizers (natural gas),
pesticide
Pesticides are substances that are meant to control pests. This includes herbicide, insecticide, nematicide, molluscicide, piscicide, avicide, rodenticide, bactericide, insect repellent, animal repellent, microbicide, fungicide, and lampri ...
s (oil), and
hydrocarbon-fueled
irrigation. The development of synthetic nitrogen fertilizer has significantly supported global
population growth
Population growth is the increase in the number of people in a population or dispersed group. Actual global human population growth amounts to around 83 million annually, or 1.1% per year. The global population has grown from 1 billion in 1800 to ...
; it has been estimated that almost half of the
Earth's population
In demographics, the world population is the total number of humans currently living. It was estimated by the United Nations to have exceeded 8 billion in November 2022. It took over 200,000 years of human prehistory and history for the ...
are currently fed as a result of synthetic nitrogen fertilizer use. According to head of a fertilizers commodity price agency, "50% of the world's food relies on fertilisers."
Environmental effects

The burning of fossil fuels has a number of negative
externalitiesharmful environmental impacts where the effects extend beyond the people using the fuel. The actual effects depend on the fuel in question. All fossil fuels release when they burn, thus accelerating
climate change. Burning coal, and to a lesser extent oil and its derivatives, contribute to
atmospheric particulate matter, smog and
acid rain
Acid rain is rain or any other form of precipitation that is unusually acidic, meaning that it has elevated levels of hydrogen ions (low pH). Most water, including drinking water, has a neutral pH that exists between 6.5 and 8.5, but acid ...
.

Climate change is largely driven by the release of greenhouse gasses like , with the burning of fossil fuels being the main source of these emissions. In most parts of the world climate change is
negatively impacting ecosystems. This includes contributing to the extinction of species and reducing people's ability to produce food, thus adding to the problem of
world hunger. Continued rises in global temperatures will lead to further adverse
effects on both ecosystems and people, with the
World Health Organization having stated climate change is the greatest threat to human health in the 21st century.
Combustion of fossil fuels generates
sulfuric
Sulfur (or sulphur in British English) is a chemical element with the symbol S and atomic number 16. It is abundant, multivalent and nonmetallic. Under normal conditions, sulfur atoms form cyclic octatomic molecules with a chemical formula ...
and
nitric acids, which fall to Earth as acid rain, impacting both natural areas and the built environment. Monuments and sculptures made from
marble and
limestone are particularly vulnerable, as the acids dissolve
calcium carbonate.
Fossil fuels also contain radioactive materials, mainly
uranium and
thorium, which are released into the atmosphere. In 2000, about 12,000
tonnes of thorium and 5,000 tonnes of uranium were released worldwide from burning coal. It is estimated that during 1982, US coal burning released 155 times as much radioactivity into the atmosphere as the
Three Mile Island accident.
Burning coal also generates large amounts of
bottom ash
Bottom ash is part of the non-combustible residue of combustion in a power plant, boiler, furnace or incinerator. In an industrial context, it has traditionally referred to coal combustion and comprises traces of combustibles embedded in formin ...
and
fly ash
Fly ash, flue ash, coal ash, or pulverised fuel ash (in the UK) plurale tantum: coal combustion residuals (CCRs)is a coal combustion product that is composed of the particulates (fine particles of burned fuel) that are driven out of coal-fired ...
. These materials are used in a wide variety of applications (see
Fly ash reuse), utilizing, for example, about 40% of the United States production.
In addition to the effects that result from burning, the harvesting, processing, and distribution of fossil fuels also have environmental effects. Coal mining methods, particularly
mountaintop removal and
strip mining, have negative environmental impacts, and
offshore oil drilling poses a hazard to aquatic organisms. Fossil fuel wells can contribute to methane release via
fugitive gas emissions.
Oil refineries also have negative environmental impacts, including air and water pollution. Coal is sometimes transported by diesel-powered locomotives, while crude oil is typically transported by tanker ships, requiring the combustion of additional fossil fuels.
A variety of mitigating efforts have arisen to counter the negative effects of fossil fuels. This includes a movement to use alternative energy sources, such as
renewable energy
Renewable energy is energy that is collected from renewable resources that are naturally replenished on a human timescale. It includes sources such as sunlight, wind, the movement of water, and geothermal heat. Although most renewable energy ...
.
Environmental regulation uses a variety of approaches to limit these emissions; for example, rules against releasing waste products like fly ash into the atmosphere.
In December 2020, the United Nations released a report saying that despite the need to reduce greenhouse emissions, various governments are "
doubling down
Blackjack (formerly Black Jack and Vingt-Un) is a casino banking game. The most widely played casino banking game in the world, it uses decks of 52 cards and descends from a global family of casino banking games known as Twenty-One. This fami ...
" on fossil fuels, in some cases diverting over 50% of their COVID-19 recovery
stimulus funding to fossil fuel production rather than to alternative energy. The UN secretary general
António Guterres
António Manuel de Oliveira Guterres ( , ; born 30 April 1949) is a Portuguese politician and diplomat. Since 2017, he has served as secretary-general of the United Nations, the ninth person to hold this title. A member of the Portuguese Socia ...
declared that "Humanity is waging war on nature. This is suicidal. Nature always strikes backand it is already doing so with growing force and fury." However, Guterres also said there is still cause for hope, anticipating
Joe Biden's plan for the US to join other large emitters like China and the EU in adopting targets to reach
net zero emissions by 2050.
Illness and deaths
Environmental pollution from fossil fuels impacts humans because
particulates and other air pollution from fossil fuel combustion cause illness and death when inhaled. These health effects include premature death, acute respiratory illness, aggravated asthma, chronic bronchitis and decreased lung function. The poor, undernourished, very young and very old, and people with preexisting respiratory disease and other ill health are more at risk. Global air pollution deaths due to fossil fuels in 2018 have been estimated at over 8 million people, nearly 1 in 5 deaths worldwide.
While all energy sources inherently have adverse effects, the data shows that fossil fuels cause the highest levels of greenhouse gas emissions and are the most dangerous for human health. In contrast, modern renewable energy sources appear to be safer for human health and cleaner. The death rate from accidents and air pollution in the EU are as follows per terawatt-hour: coal (24.6 deaths), oil (18.4 deaths), natural gas (2.8 deaths), biomass (4.6 deaths), hydropower (0.02 deaths), nuclear energy (0.07 deaths), wind (0.04 deaths), and solar (0.02 deaths). The greenhouse gas emissions from each energy source are as follows, measured in tonnes: coal (820 tonnes), oil (720 tonnes), natural gas (490 tonnes), biomass (78–230 tonnes), hydropower (34 tonnes), nuclear energy (3 tonnes), wind (4 tonnes), and solar (5 tonnes). As the data shows, coal, oil, natural gas, and biomass cause higher death rates and higher levels of greenhouse gas emissions than hydropower, nuclear energy, wind, and solar power. Scientists propose that 1.8 million lives have been saved by replacing fossil fuel sources with nuclear power.
Phase-out
Just transition
Divestment
Industrial sector
In 2019,
Saudi Aramco
Saudi Aramco ( ar, أرامكو السعودية '), officially the Saudi Arabian Oil Company (formerly Arabian-American Oil Company) or simply Aramco, is a Saudi Arabian public petroleum and natural gas company based in Dhahran. , it is one of ...
was listed and it reached a US$2 trillion valuation on its second day of trading,
after the world's largest initial public offering.
Economic effects
Air pollution from fossil fuels in 2018 has been estimated to cost US$2.9 trillion, or 3.3% of the global
gross domestic product (GDP).
Subsidies
Lobbying activities
See also
*
Abiogenic petroleum origin – a proposal that petroleum is not a fossil fuel
*
Bioremediation
*
Carbon bubble
*
Eco-economic decoupling
*
Environmental impact of the energy industry
*
Fossil Fools Day
Fossil Fools Day is an environmental demonstration day. It occurs on April 1. The name is a play on the term fossil fuels and April Fools' Day.
Fossil Fools Day began in 2004 with coordinated actions across the United States and Canada. Subs ...
*
Fossil Fuel Beta
*
Hydraulic fracturing
Fracking (also known as hydraulic fracturing, hydrofracturing, or hydrofracking) is a well stimulation technique involving the fracturing of bedrock formations by a pressurized liquid. The process involves the high-pressure injection of "frack ...
*
Liquefied petroleum gas
Liquefied petroleum gas (LPG or LP gas) is a fuel gas which contains a flammable mixture of hydrocarbon gases, specifically propane, propylene, butylene, isobutane and n-butane.
LPG is used as a fuel gas in heating appliances, cooking e ...
*
Low-carbon power
Low-carbon power is electricity produced with substantially lower greenhouse gas emissions than conventional fossil fuel power generation. The energy transition to low-carbon power is one of the most important actions required to limit climate ...
*
Peak coal
*
Peak gas
*
Phase-out of fossil fuel vehicles
Phase-out of fossil fuel vehicles means stopping selling and using vehicles which are powered by fossil fuels, such as gasoline (petrol), diesel, kerosene and fuel oil: it is one of the three most important parts of the general fossil fuel phase ...
*
Shale gas
Notes
References
Further reading
* Barrett, Ross; Worden, Daniel (eds.), ''Oil Culture''. Minneapolis, MN:
University of Minnesota Press, 2014.
* Bob Johnson, ''Carbon Nation: Fossil Fuels in the Making of American Culture''. Lawrence, KS:
University Press of Kansas, 2014.
External links
Global Fossil Infrastructure Tracker
Centre for Research on Energy and Clean Air
{{DEFAULTSORT:Fossil Fuel