Climate Change and Ozone Loss

1
Climate Change and Ozone Loss

• Chapter 20

2
The Greenhouse Effect

• We know that short wave radiation from the sun
  passes through the air to earth with little
  difficulty, excepting that clouds and certain
  pollutants reflect sunlight back into space. The
  radiation that reaches the ground/water warms it
  and then is reradiated as long wave radiation.
  This long wave radiation is slow to escape
  through the atmosphere and therefore keeps us
  considerably warmer. (Thankfully! We would be
  at -18ºC otherwise, bbhhuuurrrr!)

3
Do you know?

1. What are the four most important greenhouse
   gases?
2. Which gas is believed to be most directly
   responsible for global warming?
3. How much is the earth expected to warm in this
   century?
4. What are three things that make global warming
   effects hard to predict?

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Greenhouse gases

• Water vapor is the most important, but is
  variable and hard to determine if we impact
  directly
• Carbon dioxide is the largest of the manufactured
  gases, mostly from burning fossil fuels
• Ozone is a greenhouse gas in the troposphere
• Methane from the anaerobic breakdown of organic
  matter
• Nitrous Oxide (N2O) from smog and nylon
  production, burning coal and biomass
• CFCs in the troposphere act as a greenhouse gas

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Global Warming

• Carbon dioxide has been steadily increasing over
  the last forty years and many scientists believe
  that global warming is occurring due to increased
  amounts of this gas
• Source- Canadian Climate Center, Hadley Center
  (UK), Intergovernmental Panel on Climate Change
• 1990 was the hottest decade on record
  (coincidence?)

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How hot will we get?

• Scientists believe that we will increase between
  1 3.5ºC or 1.8 6.3 ºF (now thats hot)
• Realize that a 1ºC increase would make the planet
  hotter than it has been in 10,000 years

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Why is global warming hard to predict?

• Solar output varies
• Oceans absorb unknown amounts of energy
• Clouds reflect light and will vary with changing
  moisture content in troposphere
• Ice reflects light and will change with
  temperature and precipitation
• Global weather/climate pattern are not fully
  understood

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Global warming effects

• Warmer oceans will release stored up carbon
  dioxide further warming planet
• Melting ice will not reflect sunlight further
  warming planet
• Melting permafrost will release trapped methane
  further warming planet
• Positive Feedback Loops!!!

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Global warming effects

• Warmer oceans may have different current
  patterns
• Disrupts normal weather patterns causing
  increased weather related catastrophe
• Can kill reef/fish ecosystems
• Change wind patterns shift pollution to new areas

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Global warming effects

• With increased carbon dioxide some plants may
  flourish reducing/removing carbon dioxide from
  the air, but as they decompose they release more
  methane into the air
• The worlds ecosystems are too complex for us to
  properly model on computers at this time