Fuels and Earth Science: The Atmosphere

The atmosphere comprises different layers: troposphere, stratosphere, mesosphere, thermosphere, and exosphere; focusing primarily on the troposphere and stratosphere where all weather changes and life forms are found.
In its early form, the earth’s atmosphere contained little to no oxygen. Over billions of years, oxygen levels gradually increased due to photosynthesis carried out by early plants and micro-organisms.
The composition of the modern atmosphere is approximately 78% Nitrogen, 21% Oxygen, 0.9% Argon, 0.04% Carbon Dioxide, and trace amounts of other gases.
Gases in the atmosphere absorb the Earth’s emitted radiation, helping to moderate the planet’s temperature, a phenomenon known as the greenhouse effect. This is vital for sustaining life on Earth.
The effect can intensify due to increased levels of greenhouse gases leading to the global warming and drastic climate changes we see today.
Human activities such as burning fossil fuels, deforestation, and industrial processes lead to increased Carbon Dioxide, methane, and nitrous oxide in the atmosphere, which in turn contribute to an enhanced greenhouse effect.
Carbon dioxide is considered a significant contributor to global warming due to the large quantities produced by burning fossil fuels.
The chemistry of the atmosphere involves a number of key reactions, including the formation and decay of ozone in the stratosphere. Ozone protects life on Earth from harmful ultraviolet (UV) radiation.
Air pollution involves harmful substances being released into the atmosphere, this can be categorised into primary and secondary pollutants. Primary pollutants are directly emitted from the source while secondary pollutants form in the air when primary pollutants react or interact.
Primary pollutants can include sulphur dioxide, nitrogen oxides, carbon monoxide, volatile organic compounds, and particulates, while secondary pollutants include ozone, nitrogen dioxide and sulphur trioxide.
Solutions to air pollution include: shifting to renewable energy sources, increasing energy efficiency, improving public transportation, planting trees, and adopting sustainable farming methods.
The carbon cycle is the process by which carbon is cycled through the atmosphere, oceans, land and living organisms. An imbalance in this cycle, due to excessive amounts of carbon dioxide released through human activities, leads to increased atmospheric carbon dioxide and subsequent global warming.
Fossil fuels (coal, oil, gas) are the remains of ancient plants and animals. Over millions of years, under heat and pressure, these remains turn into concentrations of carbon. Their combustion primarily releases energy in form of heat.
Biofuels are a renewable alternative to fossil fuels. They are made from plant and waste material that can naturally regenerate.
Extracting and using fossil fuels has environmental consequences, including the release of pollutants and contributing to climate change.