1. The Global Climate System and The Greenhouse Effect
SNCD0 – Climate Change

2. Components of our Climate System
Earth’s climate system is composed of four major parts that interact with one another
Atmosphere
Air
Hydrosphere
Water
Lithosphere
Land
Living Organisms

3. Atmosphere The atmosphere is a layer of gases surrounding the planet
These gases reach more than 100 km above
Earth’s surface
After this height the gases are very diffuse,
and eventually there are no gases at all
(more than 600 km)
Atmospheric Layers
Troposphere
Stratosphere
Mesosphere
Thermosphere
Exosphere

4. Atmospheric Contents The atmosphere contains several gases
~78% nitrogen
~21% oxygen
~1% is made of several gases: argon, carbon dioxide, water, ozone (O3), helium, hydrogen, methane, etc...
The proportions of gases are slightly different at different altitudes

5. Ozone Layer In the stratosphere, there is a high ozone content
This ozone is very efficient at absorbing UV radiation
The ozone layer protects us from UV light
UV light can cause cancer and can damage living organisms
Our ozone layer has sustained damage and is now much thinner than it was a century ago
Areas over the Arctic and the Antarctic have very thin ozone layers
This damage has been shown to be from the use of chlorofluorocarbons

6. Ozone Layer
The blue regions show areas where the ozone layer is thin

7. Chlorofluorocarbons
CFCs are carbon based molecules containing fluorine and chlorine bonded to the carbon
CFCs have been used for several things in the past;
Refrigerant
Dry-cleaning solution
In Spray cans
In air-conditioners

8. Chlorofluorocarbons The free chlorine atoms react with ozone
CFCs break down when reacted with UV light
𝐶𝐹𝐶𝑙 3(𝑔)
The free chlorine atoms react with ozone
𝐶𝑙 (𝑔) + 𝑂 3(𝑔) → 𝐶𝑙𝑂 (𝑔) + 𝑂 2(𝑔)
𝐶𝑙𝑂 (𝑔) + 𝑂 3(𝑔) → 𝐶𝑙 (𝑔) + 𝑂 2(𝑔)
The chlorine atoms get recreated and are able to go and react with more ozone!
Because of this, small quantities of CFCs can continually destroy large portions of the ozone layer, and take decades to leave the atmosphere UV
→ 𝐶𝐹𝐶𝑙 2(𝑔) + 𝐶𝑙 (𝑔)
Very Reactive!!

9. Montreal Protocol
In 1987, governments around the world agreed to halt all use and production of CFCs for several uses
Certain CFCs are still used, but significantly less
The ozone layer should rebuild itself over time
It is estimated to take another 50 years to get back to normal

10. Hydrosphere Includes all water on Earth
Lakes, Oceans, water vapour, and ice
Water absorbs sunlight and heats up the air around it
It takes longer to heat up and cool down than land
This allows it to keep the temperature of surrounding areas moderate
Also adds to the precipitation in surrounding areas

11. d

12. Ice Ice is very reflective 2% of the Earths water is frozen
This is part of the reason why the poles are so cold
2% of the Earths water is frozen
Increasing the temperature of the Earth causes more ice to melt
Which worsens the problem of global warming

13. Lithosphere The Earth’s crust Includes solid rock, soil, and minerals
On land and below oceans
Land formations have a large effect on temperature
Altitude
As altitude increases, the air pressure and temperature drops

14. Mountain Effect As warm, humid air rises up it cools
The cool air forms clouds, and eventually precipitation
This leaves cool, dry air moving overtop of the mountain
This is the reason why the prairies are so dry

15. Living Things
Living things excrete gases into the atmosphere and change its composition
Carbon dioxide, methane, oxygen
Carbon dioxide and methane are “heat sinks”
This means they are really good at absorbing light and trapping it in the atmosphere as heat
They contribute greatly to the “greenhouse effect”

16. Greenhouse Effect Gases in the atmosphere absorb light from the sun
They can also absorb light that is reflected from the surface of the Earth
This light is absorbed, heating up the air
It can be re-emitted by the gases in the atmosphere and spread throughout the atmosphere
This effectively traps heat in the atmosphere for a long period before it is lost to space as infrared radiation

18. Greenhouse Gases Carbon dioxide
~ % of the atmosphere
Causes ~25% of the natural greenhouse effect on Earth
Carbon dioxide is released into the atmosphere naturally
Cellular respiration
Forest fires
Decomposition of previously living organisms
Carbon dioxide is also released through human activities
Combustion of fossil fuels and garbage

20. Carbon Sinks There are several things that trap carbon Carbon sinks
And thus remove carbon dioxide from the atmosphere
They are called carbon sinks
Carbon sinks
Plants – photosynthesis
Living organisms – mainly composed of carbon
Marine life – Shells
Rocks and sediment
Losing carbon sinks increases the amount of CO2 in the atmosphere

21. Water Vapour
Water vapour accounts for ~ 66% of the greenhouse effect on Earth
The amount of water vapour in the atmosphere depends on the temperature of the air
Ranges from trace amounts (less than 0.1%) to 4% of air
Warm air holds more water vapour than cold air
This generates a feedback loop
A process where the result influences the original process

22. Water Vapour Feedback Loop
Warm air holds more water
Water vapour retains heat,
and heats up the air
This is a positive feedback loop, where the result of the
process increases the effect

23. Methane
Methane (CH4) is about 23 times better at retaining heat than carbon dioxide
But there is very little in the atmosphere
The concentration of methane has steadily increased since the industrial age
Pre-industry = 0.7 ppm (0.7 molecules in every million air particles)
Modern day = ppm (~ 1.8 molecule in every million air particles)
It has more than doubled!
Methane is produced in plant decomposition and through animal digestion

24. Ozone and Nitrous Oxide
Ozone O3
Found in the stratosphere mainly
Can be formed in the troposphere when car emissions react with UV light producing smog (ozone one part of smog)
Nitrous Oxide N2O
Almost 300 times as effective as carbon dioxide at retaining heat
Very little in the atmosphere
Produced by bacteria in soil and water and also in combustion
Pre-industry = 270 ppb
Modern-day = 321 ppb

25. How do Gases trap Infrared Radiation?
When molecules absorb light it causes the atoms to vibrate back and forth
Thus heating them up
The more atoms, the more energy can be absorbed
Vibration Videos N N N N O

26. Homework
Climate System pg 335 #1 – 7
Greenhouse Effect pg 342 #1 – 7