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 +15 o C Without the Greenhouse effect, the Earth would have an avg. temp of -18 o C

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 1800’s Industrial Age

Earth’s Atmosphere: N 2 : 78.08%O 2 : 20.95% Ar:.93%Trace Gases: 0.04%

Most atmospheric gases do not absorb radiation (N 2, O 2, Ar, H 2, Ne, Kr) Some gases do, called greenhouse gases (GHG’s): H 2 OCO 2 CH 4 O 3 N 2 O

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

CO 2 concentration is 385ppm – % of Earth’s atmosphere Before the Industrial age, it was 280ppm Causes ¼ of greenhouse effect Natural SourcesAnthropogenic Sources Cellular respiration Volcanic eruptions Burning of organic matter (forest fires) Burning fossil fuels Coal-based power plants natural gas heating industrial processes Deforestation

Very efficient at absorbing radiation (23x more powerful than CO 2 ) Pre-industrial concentration was 0.700ppm Modern concentration is 1.785ppm (2.55x higher) Natural SourcesAnthropogenic Sources Plant decomposition Animal digestion (cow farts) Natural gas pipelines Rice and cattle farming Decay in landfills and sewage Coal mining Deforestation

Relationship between CO 2 and Temperature Do the temperature and CO 2 lines look similar? Let’s overlap the two lines to make sure.

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

A scale that tells us how much time in the Sun would cause sunburn on a specific day Index up CategoryLowModerateHighExtreme Average time to sunburn > 1 hour~ 30 mins~ 20 mins< 15 minutes

300x more effective at absorbing energy than CO 2 Pre-industrial concentration was 270 ppb Modern concentration of 321 ppb (1.2x more) Natural SourcesAnthopogenic Sources Soil and water bacteria Livestock feed and waste Fertilizers Fossil fuels Sewage treatment

GasConcentrationHeat Trapping Ability Anthropogenic Source Preindustrial2008 CFC’s (Chloroflu ro- carbons) Trace251ppt (CFC-11) 525ppt (CFC-12) 1000’s of times greater than CO 2 (Can last more than 50K years) Refrigerants (refrigerators and air conditioners) Sulfur hexafluo ride None7ppt22,800x that of CO 2 (lasts for 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 Least

Walkabout Walk around to other groups, and compare your results to others Copy the following chart into your notes:

Producing and Using Energy 324 Transportation 190 Fugitive Emissions 67 Agriculture 62 Industrial Processes 54 Waste Management 21 Land use and Forestry 20 Pg. 390

Solutions Brainstorming

Why should we worry about the greenhouse effect? Wouldn’t it be great is Canadian winters were warmer, and summers longer?

Temperature Change Data

Kilimanjaro 1970

Kilimanjaro 2000 Ice onKilimanjaro Year Area (km 2 )