human influences on the environment

• effects of global warming (4)

  - ocean temperatures increase cause melting of ice caps: rising sea levels, flooding, coral bleaching

  - increasing temps: extreme weather

  - change/loss of habitat

  - less biodiversity as food chains disrupted and extinction rates increase
• the greenhouse effect (5)

  1) sun emits rays into earth's atmosphere

  2) heat bounces back from earth's surface

  3) some heat reflected back out into space

  4) some heat absorbed by greenhouse gases and trapped within earth's atmosphere (normal)

  5) as greenhouse gases levels rise due to human activities, earth's average temp rises beyond normal (enhanced greenhouse effect) causing global warming
• greenhouse gases sources - CFCs


  - man-made chemicals once used in aerosol sprays and fridges

  - most countries agreed to stop producing them as they damage ozone layer

  - some cfcs still remain (e.g leaks from old fridges)
• greenhouse gases sources - methane


  - rotting plants in marshland; cattle-rearing; rice growing
• greenhouse gases sources - nitrous oxide


  - fertilisers, engines of vehicles
• greenhouse gases sources - carbon dioxide


  - deforestation, fossil fuels
• greenhouses gases sources - water vapour


  - rivers, lakes
• greenhouse gases

  - gases that absorb infrared radiation from the sun

  - trap it above the earth's surface which leads to the increase of the earth's temperature
• dangers of carbon monoxide


  - binds irreversibly to haemoglobin, reducing their capacity to carry oxygen

  - leads to tiredness, unconsciousness or even death in severe cases

  - in pregnant women, insufficient oxygen affects growth of fetus
• carbon monoxide sources


  - waste gases in exhaust from cars - burning petrol

  - cigarette smoke
• air pollution - carbon monoxide


  - released when fossil fuels are burnt through incomplete combustion
• acid rain effects


  - acid rain makes rivers too acidic - aquatic organisms die

  - corrodes metals & limestone in buildings

  - leeches minerals out of soil so plants and trees cannot survive
• air pollution - sulfur dioxide


  - released when fossil fuels are burnt
• acid rain formation

  - acid rain is formed when sulfur dioxide dissolves in water droplets in clouds