GCSE Chemistry revision

Human activities which contribute to an increase in greenhouse gases in the atmosphere

Carbon dioxide and methane as greenhouse gases

AQA 4.9.2.2 Foundation & Higher

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The atmosphere is a protective layer of gases surrounding Earth that acts like an insulating blanket, keeping the planet at a stable, warm temperature.
Short wavelength radiation from the Sun passes through the atmosphere, hits Earth's surface, and is then re-emitted or reflected back as longer wavelength radiation.

1. The Atmosphere as Earth's Insulating Blanket AQA

The atmosphere is a protective layer of gases surrounding Earth that acts like an insulating blanket, keeping the planet at a stable, warm temperature.
Short wavelength radiation from the Sun passes through the atmosphere, hits Earth's surface, and is then re-emitted or reflected back as longer wavelength radiation.

Greenhouse gases in the atmosphere absorb outgoing long wavelength radiation and reemit it in random directions, trapping heat energy close to Earth's surface.
This process of absorption and re-emission by gas particles repeats continuously, keeping Earth warmer than it would be without an atmosphere.
Key greenhouse gases include carbon dioxide (CO₂), methane (CH₄), and water vapour.

2. The Greenhouse Effect Explained AQA

Greenhouse gases in the atmosphere absorb outgoing long wavelength radiation and reemit it in random directions, trapping heat energy close to Earth's surface.
This process of absorption and re-emission by gas particles repeats continuously, keeping Earth warmer than it would be without an atmosphere.
Key greenhouse gases include carbon dioxide (CO₂), methane (CH₄), and water vapour.

Burning fossil fuels releases carbon that was locked inside the fuel as carbon dioxide into the atmosphere.
Deforestation reduces the number of trees available to carry out photosynthesis, which is the key process that removes CO₂ from the atmosphere.
Both factors together cause CO₂ concentrations in the atmosphere to increase steadily.

3. Rising Carbon Dioxide Levels AQA

Burning fossil fuels releases carbon that was locked inside the fuel as carbon dioxide into the atmosphere.
Deforestation reduces the number of trees available to carry out photosynthesis, which is the key process that removes CO₂ from the atmosphere.
Both factors together cause CO₂ concentrations in the atmosphere to increase steadily.

Farm animals produce methane during digestion, which is then released directly into the atmosphere.
Decomposition of waste by microorganisms also releases significant amounts of methane into the atmosphere.