Present Composition of the Atmosphere

Present Composition of the Atmosphere

Composition and Proportions

• The current atmosphere is primarily composed of nitrogen (78%) and oxygen (21%).
• Trace gases make up the remaining 1%; these include argon, carbon dioxide, water vapour, and various noble gases.

Oxygen and Life

• Oxygen in the atmosphere is a result of photosynthesis by plants and algae over billions of years.
• This oxygen has allowed the evolution and sustenance of oxygen-breathing life forms, including humans.

Carbon Dioxide and Climate Change

• The amount of carbon dioxide in the atmosphere is a fraction of a percent, but it has a large impact on the Earth’s climate.
• Levels of carbon dioxide have risen significantly since the industrial revolution due to the combustion of fossil fuels (coal, oil, and natural gas).
• This increase is linked to global warming and climate change.

The Role of the Atmosphere

• The atmosphere serves several critical roles beyond just providing oxygen for organisms to breathe.
• It protects life from harmful UV radiation, assist in the circulation of water (the water cycle), and helps regulate the Earth’s temperature (the greenhouse effect).

Human Influence

• Recent human activities, particularly industrialisation, have significantly impacted the composition of the atmosphere.
• Increases in greenhouses gases, primarily carbon dioxide and methane, have led to ever-increasing average global temperatures, known as global warming.
• Other pollutants, such as sulphur and nitrogen oxides, have led to problems like acid rain.