Global Warming

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					       What is global warming?
• It’s an increase in the average temperature on
  earth. We use the words “climate change”
  because we see changes not only in
  temperature, but also atmospheric gases,
  precipitation, wind patterns etc.
         Why is this happening?
• Global warming is primarily caused by increases
  in greenhouse gases released by human activity
  (carbon dioxide, methane, nitrous oxide) which
  all increase earths ability to retain thermal energy
• The sunlight striking earth’s surface is converted
  to thermal energy and is reflected back into
  space. The greenhouse gases trap some of this
  thermal energy (heat) causing earths surface to
  become warmer (this is known as the greenhouse
        Why is this happening?
• The difference between the absorbed energy
  and the bounced energy is called the “energy
• If more energy is kept on earth, earth gets
  warmer. If more energy is bounced into space,
  earth gets cooler
• Global warming and the greenhouse affect are
  not the same thing!
• Global Warming = increase in the average
  temperature on earth
• Greenhouse effect = the process that keeps
  Earths temperatures relatively stable
• The enhancement of the earths greenhouse
  effect is the main CAUSE of global warming
   Implications of Global warming
• Burning of fossil fuels and deforestation lead
  to increased levels of CO2 (necessary for
• Changes in rainfall have positive and negative
  affects on agriculture. Some areas are getting
  plenty of rain, and others not enough.
   Implications of Global warming
• Water supplies may decrease as precipitation
  drops and evaporation rates increase
• Extinction of many species – polar bears are
  losing their habitats on ice sheets as they melt
• Higher ocean temperatures and higher acidity
  in water (due to absorption of CO2 forming
  carbonic acid) affecting aquatic life
           What it all means…
• Scientists still don’t have a
  complete understanding of
  how oceans, air, and climate
  are related
• There is an agreement that
  human activity is a cause of
  global warming
           What it all means…
• This is why weather and climate forecasting in
  the long term remains an inexact science. We
  can’t predict the weather in over 2 weeks
  time, but scientists can forecast the overall
  earth climate change into the future