Evidence

• Describe how the greenhouse effect works

  The sun's energy arrives as short wave radiation

  Short wave rays are able to travel through greenhouse gasses

  The energy is reflected off the earth as long wave radiation

  Long wave energy is unable to pass through greenhouse gasses and are reflected back to earth

  Greenhouse gasses act like a blanket around the earth

  This traps the heat causing the planet to warm up
• Glacial period meaning


  Global cooling
• Interglacial period meaning


  global warming
• What are 4 greenhouse gasses?

  Carbon dioxide

  Methane

  Nitrous oxide

  Water vapour
• What are the 4 types of evidence for climate change?

  Ice cores

  Tree trunk growth circles

  Historical records

  sea level change
• How do ice shows that the climate is changing?

  scientists are able to drill deep into the ice to extract cylindrical cores, the thin layers can be dated by analysing the trapped molecules such as carbon dioxide, so they can calculate the temperature of the atmosphere when the snow fell
• How do tree rings provide evidence for climate change?

  The width of the tree rings suggests the environmental conditions that year, if there is good rainfall and its moist, then the rings will be wider. During harsh conditions, the rings are narrower
• How do historical records provide evidence for climate change and give a negative of this

  Cave paintings of animals in france depict nature as it was 40000 years ago, a period of time when the climate changed significantly

  A problem with this is dating accurately when it was drawn
• How do sea level rises provide evidence for climate change and what are the two reasons?


  The average global sea level has risen between 10cm and 20cm in the past 100 years

  They have risen because:

  when temperature rises ice caps melt, more water flows into the sea

  When ocean water warms it expands in volume, this is called thermal expansion
• 2 human activities which are increasing global temperatures:


  Burning fossil fuels in factories which creates greenhouse gasses, the carbon dioxide reflects outgoing radiation back to the surface (blanket)

  .

  Increased cattle farming increases the amount of methane in the atmosphere, which contributes to the greenhouse effect acting like an insulating blanket