The Greenhouse Effect
• Natural process – Earth’s surface absorbs infrared radiation from Sun. Gases and clouds in the atmosphere trap this energy and radiate it back in all directions.
• This makes Earth’s avg. temp about +15oC• Without the Greenhouse effect, the Earth
would have an avg. temp of -18oC
Some terms:
Parts per million (ppm) – a measurement of the concentration of gas (also ppb, and ppt)
Anthropogenic – resulting from human influencePre-Industrial – before the 1800’s Industrial Age
Greenhouse Gases
• Most atmospheric gases do not absorb radiation (N2, O2, Ar, H2, Ne, Kr)
• Some gases do, called greenhouse gases (GHG’s):
H2O CO2
CH4 O3
N2O
Water Vapour (H2O(g))
• Concentration in atmosphere depends on temp.
• Causes 2/3 of 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
Carbon Dioxide (CO2)• CO2 concentration is 385ppm
– 0.0385% of Earth’s atmosphere• Before the Industrial age, it was
280ppm• Causes ¼ of greenhouse effect
Natural Sources Anthropogenic Sources
•Cellular respiration•Volcanic eruptions•Burning of organic matter (forest fires)
• Burning fossil fuels• Coal-based power plants• natural gas heating• industrial processes • Deforestation
Carbon Source or Sink?
• Oceans & healthy forests are carbon sinks – remove C from atmosphere and store it in different forms (i.e. C6H12O6)
• Damaged forests (insect, fires, deforestation) are carbon sources – speed up decomposition and CO2 emissions
*not necessarily more is released… just faster rate since trees will eventually die
Methane (CH4)• Very efficient at absorbing
radiation (23x 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
Relationship between CO2 and TemperatureDo the
temperature and CO2 lines look
similar?
Let’s overlap the two lines to make sure.
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
UV index: a Canadian invention
• A scale that tells us how much time in the Sun would cause sunburn on a specific day
Index 0-3.9 4.0-6.9 7.0-8.9 9.0-up
Category Low Moderate High Extreme
Average time to sunburn
> 1 hour ~ 30 mins ~ 20 mins < 15 minutes
Nitrous Oxide (N2O)
• 300x more effective at absorbing energy than CO2
• Pre-industrial concentration was 270 ppb
• 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
Other GHG’sGas Concentration Heat Trapping
AbilityAnthropogenic Source
Preindustrial 2008
CFC’s(Chlorofluro-carbons)
Trace 251ppt (CFC-11)525ppt (CFC-12)
1000’s 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
Sources of GHG’s• Work in groups of 3 or 4 (your teacher
will assign your groups)• Get a package of pictures from your
teacher• Look over the pictures, and read the
captions, and rank them according to which you think will be the greatest and least sources of GHGs
• Arrange your rankings according to the diagram to the right.
Most
Second Most
Middle Middle Middle
Least Least
Walkabout
• Walk around to other groups, and compare your results to others
• Copy the following chart into your notes:
Source CO2 Equivalent (megatonnes per year)
Solution(Individual)
Solution(Gov/Business)
CO2 Emissions
Canada’s Emissions (in megatonnes per year CO2 equivalent)
Producing and Using Energy 324
Transportation
190
Fugitive Emissions
67
Agriculture
62
Industrial Processes
54
Waste Management
21Land use and Forestry
20
Pg. 390
Solutions Brainstorming
• To limit the effects of climate change we need to limit the gases we are emitting, because it is these gases that are causing climate change
• In the last two columns of your table, brainstorm solutions for each source.
• Organize your solutions by individual, or govt/business– Individual solutions are things that all of us can do, likely
starting today– Govt/Business solutions are those that require the
cooperation of governments, and/or businesses and other institutions
Source Solution(Individual)
Solution(Gov/Business)
Energy Turn out the lightsUnplug small appliances
Only use heat/AC when necessaryHang clothes to dryWash dishes in sink
Have Earth Days more oftenInstall solar panels
Carbon TaxEnerGuide appliances
Transport Walk instead of driveUse public transit
CarpoolLongboard/bike etc
Charge higher bus fee/or gas feesFord is making a solar powered car
Fugitive emissions Drive less Promote better technologies in oil extraction
Agriculture Buy locally grown foodGrow your own food
Increase tax on imported food
Industrial Processes Buy less Promote efficiencies in manufacturing
Waste Management Reusable water bottles Recycling programs in all citiesCharge for garbage
Forestry Use less paperUse only recycled paper
Plant trees
Cut 1 plant 2Laptop/tablet for schools
Who Cares?
• Why should we worry about the greenhouse effect?
• Wouldn’t it be great is Canadian winters were warmer, and summers longer?