The greenhouse effect

• Greenhouse gases trap energy from the sun how?

  • temp of Earth is balance between energy from sun and energy radiates back out into space
  • gases in atmosphere absorb most of heat that normally radiates out into space and re-radiate in all directions this is greenhouse effect
  • if this didn't happen - at night there nothing to keep any energy in and we'd get very cold
  • different greenhouse gases that keep energy in - water vapour, carbon dioxide and methane
  • Humans increase amount of CO2 in atmosphere - also increasing levels of other gases that can act as greenhouse gases - CFC and nitrous oxide - enhanced the greenhouse effect - result of this the Earth is heating up - global warming - causes melting of polar ice caps and rise of sea levels
• what human activity produces greenhouse gases?

  • CO2 - humans release CO2 into atmosphere - car exhausts, industrial processes and burning fossil fuels - deforestation for timber and clear land for farming - affects levels of of CO2 in atmosphere
  • Methane - Methane gas produced naturally from marshland or rotting plants also rice growing and cattle rearing
  • Nitrous oxide - released from bacteria in soils and the ocean - lot more released from soils after fertiliser is used - released from vehicle engines and industry
  • CFC's - man-made chemicals once used as aerosol sprays and fridges - very powerful greenhouse gases - most countries agreed to not produce them as they damage the ozone layer and prevent UV radiation from reaching the earth - some CFC's still remain from leaks from old fridges