The Greenhouse Effect

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The Greenhouse Effect
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Earths Atmosphere

• Earths Atmosphere
• N2 78.08 O2 20.95
• Ar .93 Trace Gases 0.04

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The Greenhouse Effect

• A natural process by which gases and clouds
  absorb infrared radiation emitted from Earths
  surface and radiate it
• This absorbed energy then can be radiated back to
  Earths surface and atmosphere
• Without the Greenhouse effect, the Earth would
  have an average temperature of -18oC
• The average temperature is closer to 15oC

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Some terms

• Parts per million (ppm) a measurement of the
  concentration of gas (also ppb, and ppt)
• Anthropogenic resulting from human influence
• Pre-Industrial before the 1800s Industrial Age

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Greenhouse Gases

• Most atmospheric gases do not absorb radiation
  (N2, O2, Ar, H2, Ne, Kr)
• Some gases, which exist in low atmospheric
  concentrations, are greenhouse gases (GHGs)
• These include
• H2O CO2
• CH4 O3
• NO2

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Water Vapour (H2O(g))

• Cause of about 2/3rds of Earths natural
  greenhouse effect
• Feedback loop
• The warmer the air, the more water vapour the air
  can hold
• The more water vapour the air can hold, the
  warmer it gets

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Methane (CH4)

• Very efficient at absorbing radiation (23 times
  more powerful than CO2)
• Pre-industrial concentration was 0.700ppm
• Modern concentration is 1.785ppm (2.55x higher)

Natural Sources Anthropogenic Sources
Plant decomposition Animal digestion (cow farts) Natural gas pipelines Rice and cattle farming Decay in landfills and sewage Coal mining Deforestation
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Ozone (O3)

• Ozone exists naturally in the stratosphere
  (20-60km up), and protects against UV
• Ozone in troposphere (0-20km up) is a GHG
• Causes smog in cities

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Nitrous Oxide (NO2)

• More than 300x more effective than CO2
• Pre-industrial concentration of 270 ppb (parts
  per billion)
• Modern concentration of 321 ppb (1.2x more)

Natural Sources Anthopogenic Sources
Soil and water bacteria Livestock feed and waste Fertilizers Fossil fuels Sewage treatment
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Carbon Dioxide (CO2)

• CO2 concentration is 385ppm
• (parts per million)
• 0.0385 of Earths atmosphere
• Before the Industrial age,
• it was 280ppm
• Oceans act as carbon sinks as the temperature
  rises more CO2 is released by the oceans

Natural Sources Anthropogenic Sources
Cellular respiration Volcanic eruptions Burning of organic matter (forest fires) Burning fossil fuels Deforestation
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Relationship between CO2 and Temperature
Do the temperature and CO2 lines look similar?
Lets overlap the two lines to make sure.
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Other GHGs
Gas Concentration Concentration Heat Trapping Ability Source
Gas Preindustrial 2008 Heat Trapping Ability Source
CFCs (Chlorofluro-carbons) Trace 251ppt (CFC-11) 525ppt (CFC-12) 1000s of times greater than CO2 (Can last more than 50K years) Refrigerants (refrigerators and air conditioners)
Sulfur hexafluoride None 7ppt 22,800x that of CO2 (lasts for 3000 years) Electrical utilities, and magnesium production
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Canadas Emissions (in megatonnes per year CO2
equivalent)
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Canadian Forests

• Healthy forests are Carbon sinks store CO2
• Unhealthy forests that occur due to
• insect infestation
• deforestation
• fires
• cause an increase in decomposition and large
• amounts of CO2 to enter the atmosphere

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Who Cares?

• Why should we worry about the greenhouse effect?
  
• Wouldnt it be great is Canadian winters were
  warmer, and summers longer?

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Temperature Change Data
1880-1884
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1880-1884
1886-1890
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1896-1900
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1906-1910
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1916-1920
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1926-1930
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1936-1940
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1946-1950
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1956-1960
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1966-1970
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1976-1980
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1986-1990
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1996-2000
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2003-2007
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Kilimanjaro 1970
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Kilimanjaro 2000