the greenhouse effect

The Greenhouse Effect

1. What is the Greenhouse Effect?

• Climate Change Basics.avi

Greenhouse Gases• chemical compounds in the atmosphere that trap

heat • they retain a proportion of the sun’s heat through

the greenhouse effect. • 5 major greenhouse gases:

Gas % of Greenhouse Effect

water vapour (H2O) 36-70%carbon dioxide (CO2) 9-26%methane (CH4) 4-9%ozone (O3) 3-7%nitrous oxide (N20) 2-6%

Greenhouse GasesNelson Science1. Water Vapour:• ~ 60% of GG• quantity of water vapour depends on the

temperature of the atmosphere• they are connected through a positive

feedback loop

2. Carbon Dioxide

• ~ 25% of GG• produced from natural and human sources• volcanic eruptions, burning fossil fuels, cellular

respiration in plants and animals and decomposition

• carbon sinks – oceans and plants that absorb carbon dioxide from atmosphere and store it in a different form

The Carbon Cycle

Processes in Carbon CycleHow CO2 is added to atmosphere:1. Cellular Respiration – plants and animals breaking

down glucose to release energy• glucose + oxygen → carbon dioxide + water2. Decomposition – bacteria/fungi breaking down

dead material/wastes• if O2 is present, the carbon combines with it to

form CO2

3. Burning Fossil Fuels/Wood – combustion• fuel + oxygen → carbon dioxide + water4. Volcanoes – release CO2

How CO2 is removed from atmosphere

1. Photosynthesis – plants using sunlight to create glucose

• carbon dioxide + water → glucose + oxygen2. Dissolving into oceans• carbon dioxide dissolves into water and forms

carbonate ions and carbonic acid* trees and oceans are Carbon Sinks – absorb lg amnts

of CO2

Acid Test The Global Challenge of Ocean Acidification.avi

3. Methane• 1 molecule of CH4 traps 23 times more GG than 1 molecule CO2

• from plant decomposition in swamps and animal digestion

4. Ozone• acts as GG in troposphere when it combines with exhaust

creating smog

5. Nitrous Oxide (ha ha ha)• 300 times more powerful GG than CO2

• from natural and human sources• released by bacteria in soil and water• released in emissions from cars and factories

Anthropogenic GG

• GG always been part of our atmosphere• major increase in past 200 years due to

human activity• called anthropogenic GG• CO2 – burning fossil fuels, deforestation

• CH4 – agriculture, mining, landfills

• N2O – animal feed and wastes, fossil fuels

Feedback Loops

• the problem creates an effect that impacts the original problem

Positive Feedback – effect increases original problem

Negative Feedback – effect decreases original problem. eg. thermostat controls temp

Water Vapour Feedback

• water vapour enters the atmosphere when the climate warms up.

• it’s a GG, so causes the climate to warm up even more.

• if the climate cools down, less water vapour forms and the climate cools further

Albedo Effect• % of radiation reflected by a surface • ice has a high albedo (reflects back most UV rays)• If Earth’s temp drops slightly, more ice forms. • reflects more of UV rays, and Earth’s tempdecreases

even more• If Earth’s temp increases, more ice melts. • More UV rays are absorbed, and Earth’s temp increases

more.• Nelson ScienceDraw a diagram/flow chart of postive and negative albedo

2. Making Predictions About the Greenhouse Effect & Climate Change

i) how will world’s climate change over next 100 years if greenhouse gas emissions are not limited?

• Canadian Climate Impacts and Scenarios

ii) how will these changes affect humans?

Meltdown: A Global Warming Journey

• Meltdown A Global Warming Journey Part 1.avi