CLIMATE CHANGE

• Greenhouse effect


  1. Sun rays pass through the atmosphere

  2. Some rays reflect into space allowing earth to cool

  3. Some rays trapped by CO2 in atmosphere

  4. Increased CO2 causes more heat to retain which increases temperature
• Natural causes of climate change

  • Changes in orbit
  • Variation in heat output from sun
  • Volcanic activity
• Milankovitch cycle


  1. Eccentricity – orbit goes from circular to mildly elliptical over time

  2. Axal tilt – over a 41000-year period the tilt of the earth shifts

  3. Precision – earths wobble is a 26000-year cycle
• Solar outputs


  1. Sunspot – a dark spot that appears from time to time, numbers reach a minimum and maximum in a 11-year cycle

  2. Sunspot maxes – sun gives off more heat and solar flares

  3. Sunspot minimum – lower temperatures on earth
• Volcanic activity


  1. Ash can block block sun after an eruption

  2. Fine droplets of sulphuric acid act like mirrors and reflect sun radiation
• Mitigation


  Reducing the affects of climate change
• Adaptation


  Making changes to reduce the effects of climate change
• Carbon capture


  1. Removes up to 90% of CO2

  2. CO2 injected into deep rocks that used to store oil – reabsorbed into lithosphere

  3. This would be expensive to implement

  4. New technology could have faults
• Afforestation


  1. Trees remove CO2 from atmosphere via photosynthesis

  2. Cheap, looks natural

  3. Reduce flooding risk and soil erosion
• Paris agreement: First universally legally binding global climate deal

  2015
• Paris agreement goals


  • To balance greenhouse sources and sinks by 2050
  • To meet every 5 years to discuss progress
  • Keep global temperature increase >1.5
  • 100 billion USD to help developing countries
• Why agriculture change is needed

  • Rainfall and temperature will change
  • Extreme weather events will become more common
  • Distribution of pests will change
• Farmer adaptations


  • Drought resistant crops – will last
  • Shade trees – protect seedlings from sun
  • New cropping patterns – accommodate climate shifts
• Water supply


  1. Water schemes can be implemented – fog harvesting

  2. Water moved from surplus to deficit
• Water harvesting


  Water is taken from seasonal stores and stored until needed
• Proof of climate change

  • Ocean acidification – too much CO2
  • Sea levels rose 6.7 inches in last century
  • In last decade, it almost doubled
  • Increased extreme weather events
• Evidence of climate change

  • Radiation – greenhouse gasses trap radiation – can be measured
  • Stratosphere – lower part of atmosphere is warming up, but stratosphere isn't
  • Warm nights – trapped heat keeps night temperature high
• Alternative energy sources


  • HEP, solar, wind and tidal are all renewable
  • HEP caused flooding
  • Solar causes visual pollution
  • Nuclear doesn't release CO2 but is harmful and expensive
  • Expensive to implement but good in long run
• Kycto protocol


  2005
• Kycto protocol


  • Became law in 170 countries to reduce carbon emissions by 52%
  • Of major emitters, only USA and Australia signed
• Impact of climate change on agriculture

  • Some plants unable to grow
  • Can now grow other crops