Chapter 8: Dynamics of Climate
Change
Economy and Environment
8.1 Energy Transfer in the Climate
System
• Open system: The human body
receives food, water, and
nutrients and releases waste
products and heat
• Closed system: The atmosphere
allows energy to enter but
restricts other materials from
entering or exiting.
Feedback Loops in the Earth’s Closed
System
• Earth being a closed system, it must circulate
all of its matter within its boundary.
– The interactions between the earth’s materials
create a feedback loop
(i.e. A impacts B which impacts C impacting A again)
Positive Feedback Loops
• A positive feedback loop is a feedback system
where each of the items on the loops will
increases its effects every cycle
Decrease
in albedo
Increase in
global
warming
Increase in
the rate of
melting ice
Negative Feedback Loops
• A negative feedback loop is a feedback system where
each cycle brings the system closer towards
equilibrium.
– Each cycle will decrease the effects of the items in the loop
Decrease in
grades
Increase in
time studying
Decrease in
attentiveness
Increased test
perromance
Decreased
sleep time
Energy and Heat on Earth
• The earth has 3 main types of energy transfer that help to heat the
earth:
1.
Radiation: Electromagnetic radiation in the form of waves emitted by a heat
source.
- Radiation can be either absorbed, reflected or refracted.
2.
Conduction: The transfer of energy between two objects
3.
Convection: The transfer of energy due to moving objects (e.g. liquid, gas [not
solid])
Conduction, Convection, Radiation
Conduction, Convection, and Radiation
in the Earth’s Atmosphere
• On Board (Figure 8.4)
Earth’s Energy Budget
• Energy is either:
 absorbed by the clouds,
atmosphere or land (70%)
 reflected by the clouds,
atmosphere, or land (30%)
• The measure of the clouds
and land structures (ice,
snow) ability to reflect
solar radiation is known as
its albedo.
Albedo
Values for
Varies
Earth
Structures
Global Warming and Albedo
• Dark coloured earth structures mainly absorb
radiation = low albedo
• Light coloured structures reflect radiation = high
albedo
– The more ice that melts the greater amount of radiation
will be emitted resulting in increased temperatures.
– However, increased temperatures cause more evaporation,
which increases cloud cover, which increases albedo
Energy Transfer in the Oceans
• Ocean circulation occurs due to the thermohaline
circulation (affected by temperature and salt)
– The current is referred to as “the great ocean conveyer belt”
– Water at the poles is colder/saltier = more dense = sinking
– As cold water sinks, warm water rises to the surface creating a
warm surface flow.
– In this manner energy is transferred throughout the oceans
Global Warming and Thermohaline
Circulation
• Global warming causes an increase the overall
temperature
– Leads to melted ice at the poles = less saline water =
less dense water = does not sink
– Leads to increased evaporation at the tropics = more
saline water = more dense = sinking
• These effects may reverse the thermohaline
circulation or stop it entirely resulting in uneven
distribution of energy in the ocean
In Class Work Time
8.2. Greenhouse Gases and Human
Activity
• Carbon dioxide in the
Earth’s atmosphere is
currently approximately
370 ppm
• What does this mean?
• It means that of every one
million parts in the
atmosphere, 370 are
carbon dioxide
Atmosphere Composition
• 90% of the atmosphere is made up of N2
(nitrogen) and O2 (oxygen)
– These are not greenhouse gases
• Greenhouse gases are water vapour, carbon
dioxide, methane, nitrous oxide, ozone.
• Source: Processes that add greenhouse gases
• Sinks: Processes that remove greenhouse gases
Greenhouse
Gases
Sources and Sinks
• The source of carbon dioxide in the atmosphere
is primarily due to animal respiration.
– Human’s burn fossils which also contributes to
carbon dioxide
• Plants/phytoplankton remove carbon dioxide
making them carbon sinks
Methane
• Common to bogs and swamps (e.g. wetlands)
• Cattle contribute a large portion of the
methane production through gas release.
• Waste products (manure) also contributes to
methane production.
Solutions
Nitrogen Oxide
• From damp tropical soils and the oceans
• Anthropogenic sources: Chemical fertilizers,
manure, vehicle exhausts
Ozone (O3)
• Occurs naturally in the atmosphere
• Blocks harmful UV radiation
Ozone Depletion
• Ozone has been depleting for the last 30 years
• Depleted ozone allows for harmful UV radiation to
pass through the atmosphere
– Increases cancers of the skin
• Caused by chlorine containing gases
Ground Level Ozone
• Ozone can also be found at ground level due
in the form of smog
– Smog is composed of sunlight and vehicle exhaust
chemicals
– Smog causes damage to the lungs and heart
Halocarbons
• Are carbons bound by halogens
• Most common halocarbon found in the
atmosphere is chlorofluorocarbons (CFC’s)
– Are gases that have depleted the ozone over
Antarctica
– Found in solvents, cleaners, old refrigerators
Global Warming Potential (GWP)
Reducing Greenhouse Gases
• Conserve electricity:
– Energy efficient lights, new appliances, conserve.
• Improve home heating
– Update furnace, retrofit (windows and seals)
• Reduce, re-use, and recycle
– Be frugal in using products, reuse products, and
dispose in the correct bins.
8.3 Jigsaw Activity
• In this activity groups of four will be made
• Each student within the group will be given a number
(i.e. 1, 2, 3, 4)
• Each student must read these pages and summarize the
key ideas to the group along with any figures
– Student 1: Read pages 333-334 ( up to “The Global Carbon Budget”)
– Student 2: Read page 334 (“The Global Carbon Budget”) and page 335
(The carbon cycle)
– Student 3: Read page 336 (“How human act…) and page 337
– Student 4: Read pages 338-339.