The Greenhouse Effect

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

The Greenhouse Effect

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

Earth’s Atmosphere• Earth’s Atmosphere:

N2: 78.08% O2: 20.95%

Ar: .93% Trace Gases: 0.04%

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 ANTHROPOGENIC GHG’S

GHG’s Ranking Activity

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?

Temperature Change Data

1880-1884

1880-18841886-1890

1896-1900

1906-1910

1916-1920

1926-1930

1936-1940

1946-1950

1956-1960

1966-1970

1976-1980

1986-1990

1996-2000

2003-2007

Kilimanjaro 1970

Kilimanjaro 2000

Ice on Kilimanjaro

0

5

10

15

1900 1920 1940 1960 1980 2000 2020Year

Are

a (k

m2 )