human activity

• the amount of water vapour in the atmosphere is variable and changes depending on the temperature
• atmosphere contains around 0.04% CO2 and small amounts of methane
• water vapour, CO2 and methane are all greenhouse gases
• energy from the sun travels to the earth as short wavelength radiation eg UV and visible light
• some of the short wavelength radiation reflects back into space but most of it passes through the atmosphere (as short wavelength radiation doesn't interact strongly with the gas molecules in the atmosphere)

  the energy of the radiation is absorbed when it reaches the surface of the earth
• the surface od the earth now radiates the energy as long wavelength radiation as infra-red

  some of the long wavelength radiation interacts with the greenhouse gas molecules in the atmosphere - the energy in the long wavelength radiation is absorbed
• as energy is trapped in the atmosphere, this causes the temperature of the atmosphere to increase
• the greenhouse effect keeps the temperature on earth warm to support life
• levels of CO2 and methane are increasing due to human activity
• temperature of the atmosphere is rising as more energy from the sun is trapped
• rising temperatures will increase melting of the polar ice sheets and glaciers
• Increasing sea levels could lead to more flooding
• climate change can lead to more extreme weather eg more storms in the UK
• increasing temperature could change the distribution of animals
• carbon footprint: the total amount of CO2 and other greenhouse gases emitted over the full life cycle of a product, service or event
• fuels release energy when they are combusted
• incomplete combustion: carbon monoxide

  -toxic gas with no colour or smell
• sulfur: contained in coal when burned, sulfure reacts with oxygen to make sulfur dioxide
• oxides of nitrogen are produced inside engines eg in cars

  high temperatures cause nitrogen and oxygen from the air to react