Fossil fuel is a fuel formed in the geological past from the remains of living organisms. It is a fuel formed by natural processes, such as anaerobic decomposition of buried dead organisms. They contain high percentages of carbon and include petroleum, coal, and natural gas.
A fossil is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved in amber, hair, petrified wood, oil, coal, and DNA remnants. Fossil fuels are consumed for energy supply, including transport, heat and electricity production
The use of fossil fuels has begun to raise serious environmental concerns. As of 2017, the world’s primary energy sources consisted of 85% share for fossil fuels. A constitution of petroleum (34%), coal (28%), natural gas (23%). The burning of fossil fuels produces around 21.3 billion tonnes (21.3 gigatonnes) of carbon dioxide (CO2) per year. It is estimated that natural processes can only absorb about half of that amount, so there is a net increase of 10.65 billion tonnes of atmospheric carbon dioxide per year. Combustion of fossil fuels generates sulfuric, carbonic, and nitric acids, which fall to Earth as acid rain, impacting both natural areas and the built environment.
Although natural processes continually form fossil fuels, such fuels are generally classified as non-renewable resources because they take millions of years to form. A global movement towards the generation of low-carbon renewable energy is underway to help reduce global greenhouse-gas emissions. The transition from polluting fossil fuels to clean energy is already underway. Annual investment in renewables has been greater than that in fossil fuel electricity generation since 2008 and new renewable capacity has exceeded fossil fuel power each year since 2014.