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Global Climate Change
Lesson 4
Climate: A Balancing Act
Concept Question
How does the Earth’s balance between incoming and outgoing radiation regulate
climate?
Prerequisite knowledge
In addition to understanding the content from previous lessons, student should have a
basic understanding of the following concepts:
(In a web-page format, these bullets could be links to other DLOs, pages or lessons with the necessary
background information)





Earth’s planetary characteristics
o (Earth’s rotation around the sun, planetary spin and tilt)
the electromagnetic spectrum
o (What it is, the fact the different types of radiation exist, examples of types of
radiation)(ie- in a webpage format, this bullet could be a link to open Dr. Martin’s
interactive electromagnetic spectrum applet)
characteristics of atmospheric molecules
o (What clouds are primarily made up of, what types of chemical interactions occurs
between gaseous molecules)
the water cycle
o (Basic understanding of arctic ice, evaporation, clouds and rain)
general global climate features
o (weather features of equatorial, arctic, and desert regions).
Necessary Web-Based Resources
(In a web-page format, these DLO’s will show up in the left panel- perhaps there should be a menubar on
te left hand panel so that students can choose which DLO to bring up and navigate easily between DLOs)
Access to the following online KCVS digital learning objects will be necessary to
complete Lesson 4:
-Planetary Climates: A Delicate Balance
-Earth’s Energy Balance
-Greenhouse Gas IR Window
Several additional global climate change KCVS visualizations covered in previous
lessons may be helpful in understanding Lesson 4. These visualizations can be found at
www.kcvs.ca, in the Global Climate Change Visualization section.
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(In a web-page format, key images could show in the left panel and text in the riht panel. As student open
different parts of the lesson, any images or DLO’s could be shown in the left panel as the text consistently
appears in the right hand panel). http://www.guardian.co.uk/world/iceland-volcano. Photo credit- Henrik
Thorburn
Introduction
In 1821, the Icelandic mountain volanco, Eyjafjallajökull. This eruption lasted 14
months long and the large amounts of emitted ash had devastating environmental effects.
On March 20th, 2010, Eyjafjallajökull erupted again, and, by the second phase of
its eruption, had emitted 250 million cubic meters of ash into the Earth’s atmosphere. The
eruption made international headlines as the ash clouds subsequently drifted over Europe,
grounded thousands of European flight, stranded millions of passengers, and cost airlines
hundreds of millions of dollars. (in a web-page format, the video of the eruption could be on the left
panel as students read the lesson information in the right panel).
Besides disrupting travel plans, what are the impacts the 250 million cubic meters
of ash added to the atmosphere? Will the ash from this eruption continue to settle on
farmer’s fields throughout Europe and disturb agriculture? Are there serious health
implications of the increased particulate matter in the air? And what effect will the
suspended ash, high in the atmosphere, have on climate? Historically, volcanic eruptions
have been followed by periods of global cooling. It’s difficult to predict the exact effects
of the powerful Eyjafjallajökull eruption, but it’s safe to say that we may continue to see
its effects in the years to come.
This lesson explores how different features of land and air, such as atmospheric
ash particles emitted by a volcano, affect the amount of energy that is entering and
leaving the earth’s atmosphere. This energy balance, known as the earth’s radiation
balance, ultimately regulates our planet’s climate.
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Outline
(In a web-based format, there should be a top menu bar where the outline is always available- in this way,
students / teachers can navigate through the lesson in any order and at their own pace).
Topic 1: What is a Radiation Balance?
Topic 2: Incoming Solar Radiation
Topic 3: Reflection of Visible Light
Topic 4: Emission of Infrared Radiation
Topic 5: Greenhouse Gases
Topic 1: What is a Radiation Balance?
The Earth’s climate is regulated by energy flowing into and out of our planet’s
atmosphere. Various factors can affect the energy flow and therefore have an effect on local
weather and, in the long term, the climate. Radiation from the sun reaches the Earth and some of
this radiation is absorbed by the Earth and warms it up. A steady state, or radiation balance (in a
web-based format, key bolded terms could be formatted as interactive rollovers), is reached where the
amount of radiation coming in is matched by the radiation escaping from the atmosphere,
resulting in a fairly stable temperature and climate.
Planets, such as the earth, maintain a radiation balance as they are blackbody radiators
of energy. In order for a planet to act as a blackbody radiator, it must fully absorb the energy that
is incident upon it and re-emit the radiation. Planets emit and absorb different types of
electromagnetic radiation on the electromagnetic spectrum (see Lesson 3 for more information
on electromagnetic radiation- in a web-based format, this link could open up a different lesson or DLO
in a new tab). The type of radiation re-emitted (ie- visible light, infrared radiation, ultraviolet
radiation, etc.) depends on the temperature of the planet emitting the energy. For example, at
‘room temperature,’ a blackbody radiator emits radiation primarily in the infrared region. The
hotter a planet’s temperature, the lower the wavelength of the majority of the emitted radiation
(thus the higher the frequency and energy of the radiation).
Now, open the Planetary Climates: A Delicate Balance visualization.
(In a web-based format, this visualization will be available or perhaps already open in the left hand panela student / teacher should be able to actively interact with the DLO as they work through the lesson)
Explore the first few pages and review the meaning of the term radiation balance. Follow the
instructions and discover the different planetary environments. As you investigate different
planetary climates, focus on the following question: What are the factors that cause these
planets to have such different climates? Fill out Table 1.1 as you discover the information.
In order to complete Table 1.1, open the Build a Planet simulator after you have explored the
different planetary atmospheres (this can be reached from the “Go to” menu option at the top of
the page or in the ‘Earth’ section of the planetary exploration).
Once in the Build a Planet simulator, choose the “Planetary Data” option in the top menu bar.
Using your knowledge from your planetary exploration and this table, fill in the chart below. Use
the top navigation bar to go back and explore the planets again if necessary!
Table 1.1. Planetary climate characteristics
(in a webpage format, this table could be done with rollovers or in a printable pdf format for
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teachers to print off and use as a worksheet question. Perhaps on the website there could be pdf
files available for teachers with lists of questions or worksheet handouts)
Mars
Venus
Earth
Relative density of
atmosphere
Substances in
atmosphere
Relative surface
temperature
Relative distance from
the Sun
After you have completed the table, note the features of the Build a Planet simulator.
There are four factors that you can use to affect the climate of a planet. By altering these four
factors, the center bars (“incoming energy” and “outgoing energy”) can be balanced- thus
creating a radiation balance! Spend a few moments exploring this visualization. Which of the four
factors affect “energy in” bar? Which affect the “outgoing energy” bar? In Topic 2, you will
continue to use this visualizing and particularly focus on incoming solar energy. (In a classroom
setting, as a web-based resource, teachers may choose to use the build-a-planet more or less and at
different time, so easy navigation between visualizations is essential).
Topic 1 Concept Essentials
1. Why is it important for a planet to have a radiation balance?
2. What is a blackbody radiator?
3. Compare the relative frequency, wavelength, and energy of infrared, visible, and ultraviolet
radiation photons.
Think: Considering the relative energies of these types of radiation, which do you think is the
most dangerous for humans to be exposed to? Why?
Topic 2: Incoming Solar Radiation
(in a web-based format, this topic will involve switching back and forth between 2 DLOs)
After exploring the climates of Mars and Venus, let’s focus on the climate of our home
planet, Earth. The source of 99% of incoming radiation on Earth is the sun. The sun produces
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radiation mainly in the ultraviolet (UV), visible (vis) and infrared (IR) regions of the
electromagnetic spectrum.
To begin learning about incoming solar radiation, open the Earth’s Radiation Balance
visualization. (in a web-based format, this visualization will guide the student through the main content
for topic2- questions are posed so that the student will navigate through the visualization to find the
answers- navigation needs to be added to this visualization). Click on the top, left hand panel entitled
“Incoming Solar Radiation.”
Various questions are posed throughout this DLO and repeated in a list below. Take care
to work through the visualization and thoroughly understand the answers to each of the questions
posed.
Incoming Solar Radiation DLO Questions
(In web-based format, these questions could be interactive rollovers or popups- or perhaps answer
keys could be available for educators in pdf format)
1. In what region(s) of the electromagnetic spectrum is the incoming radiation from the sun?
2. Most of the energy that the earth’s atmosphere receives from the sun is radiation in the visible
region and a small portion of the sun’s energy is in the UV and IR energy regions. Is all of this
energy absorbed by the earth?
Now that you have explored a bit about incoming solar radiation, let’s consider how incoming
radiation affects the overall radiation balance of the earth. Return to the Planetary Climates DLO
and open the Build a Planet simulator. This simulator has four different climatic factors that you
can alter. Use the data below to ‘create’ Earth’s climate!
1)(In the actual visualization , these boxes could be replaced with a screenshot of the 4 boxes at these
positions)
Albedo: 0.36
Greenhouse Effect: 0.44
Distance from the Sun: 1
AU
Surface Temperature:
15’C
(In order to enter exact numbers, click on the number symbol of the slider bars.)
Note how the center two bars are balanced. The incoming radiation is equal to the outgoing
radiation! Note that the “Incoming Radiation” bar refers to radiation that is actually
absorbed by the earth’s surface. It is not describing energy at the top of earth’s atmosphere
or energy that is reflected away.
Now, move each of the sliders slightly. Which two factors affect the amount of incoming
radiation? What might Earth’s temperature be if the planet had less incoming solar radiation?
Change the distance from the sun from 1 AU to 2 AU.
2) (In the actual visualization , these boxes could be replaced with a screenshot of the 4 boxes at these
positions)
Albedo: 0.36
Greenhouse Effect: 0.44
Distance from the Sun: 2 AU
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Notice how the energy is no longer balanced. There is less energy entering the earth’s
atmosphere. In order create a new radiation balance, move the surface temperature slider so that
the energy is once again balanced. What is the new temperature? Try decreasing the distance
from the sun to 0.5AU. Now what is the surface temperature that results in an energy balance?
Note your observation in the table below.
Table 2.1: Effect of changing distance from the sun on surface temperature (in a webpage
format, this table could be done with rollovers or in a printable pdf format for teachers to print
off and use as a worksheet question. Perhaps on the website there could be pdf files available for
teachers with lists of questions or worksheet handouts)
Required temperature
change to rebalance
radiation
Increased Incoming Energy
Decreased Incoming Energy
Increased Surface Temperature
Increased Surface Temperature
Or
Or
Decreased Surface Temperature
Decreased Surface Temperature
(circle one)
(circle one)
We return to the topic of incoming radiation in topic 3, “Earth’s reflection of solar radiation.”
Topic 2 Concept Essentials
1. What is the primary source of all of Earth’s energy?
Think: It does not intuitively seem that energy that we use on a daily basis to light our desks
or heat our houses come from this source. Why is it correct to say that all of our energy
comes from this source?
2. Consider the “Build a Planet” simulator. Why and in what way does increasing the distance
from the sun affect the overall incoming radiation?
3. What type of electromagnetic radiation is used by plants in photosynthesis?
Think: How might solar cycles and the earth’s radiation balance affect plant life around
earth and agriculture?
4. Describe three different possible fates of incoming photons of visible light from the sun.
Topic 3: Reflection of Visible Light
In Topic 2, you learned about the source of incoming radiation. As mentioned, not all of
the radiation at the top of the atmosphere reaches the earth’s surface. Approximately 30% of the
energy that reaches the top of the earth’s atmosphere is reflected away from the earth. This
reflection of light away from the earth is referred to as albedo. For example, something is highly
reflective, such as ice, has a high albedo value.
To begin learning about the reflection of incoming solar radiation, open the Earth’s Radiation
Balance visualization. (in a web-based format, this visualization will guide the student through the main
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content for topic2- questions are posed so that the student will navigate through the visualization to find the
answers- navigation needs to be added to this visualization). Click on the top, right hand panel entitled
“Earth’s Reflection of Solar Radiation.”
Various questions are posed throughout this DLO and repeated in a list below. Take care to work
through the visualization and thoroughly understand the answers to each of the questions posed.
Earth’s Reflection of Solar Radiation DLO Questions
(In web-based format, these questions could be interactive rollovers or popups- or perhaps answer
keys could be available for educators in pdf format)
1.
2.
3.
4.
5.
What features of the earth and its atmosphere reflect light?
Which more effectively reflects visible light: vegetation or black soil?
How might deforestation affect the amount of light reflected away from the earth?
Which more effectively reflects visible light: water or polar ice and snow?
Considering the relative reflection ability of ice and water, how does the melting of ice caps affect
the amount of light reflected away from the earth?
6. With the radiometer image in mind, why might the earth reflect light more in specific areas than
others?
Now that you have explored what albedo is, let’s consider how it affects the overall radiation
balance of the earth. Return to the Planetary Climates DLO and open the Build a Planet
simulator. Use the Earth data below to ‘create’ our climate.
1) (In the actual visualization , these boxes could be replaced with a screenshot of the 4 boxes at these
positions)
Albedo: 0.36
Greenhouse Effect:
0.44
Distance from the Sun:
1 AU
Surface Temp.: 15’C
(In an interactive, web-based format, the portion of Topic 3 should be done by working interactively back
and forth between the DLO and the lesson)
Now that you have ‘created’ Earth, what would you expect to happen if you increase the albedo
value? Try increasing the albedo slider up to 0.5.
2) (In the actual visualization , these boxes could be replaced with a screenshot of the 4 boxes at these
positions)
Albedo: 0.5
Greenhouse Effect:
0.44
Distance from the Sun:
1 AU
What is the visual effect on the planet of moving this slider bar and what does this effect
symbolize? Now consider the central two bars- does changing the planet’s albedo affect the
incoming radiation or outgoing radiation?
By increasing the albedo, note that two central radiation bars are no longer balanced. In order to
recreate this radiation balance, try changing the surface temperature of the planet. How is the
temperature shifted in order to recreate the energy balance. Try decreasing the albedo to 0.25 and
try, once again, to create an energy balance by altering temperature. As you explore this
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visualization, complete the chart below. (In an web-based format, this table might be available as a pdf
printable worksheet or as a rollover table in the right hand lesson panel)
Table 3.1: Effect of changing albedo on surface temperature
(in a webpage format, this table could be done with rollovers or in a printable pdf format for
teachers to print off and use as a worksheet question. Perhaps on the website there could be pdf
files available for teachers with lists of questions or worksheet handouts)
Required temperature
change to rebalance
radiation
Increased Albedo
Decreased Albedo
Increased Surface Temperature
Increased Surface Temperature
Or
Or
Decreased Surface Temperature
Decreased Surface Temperature
(circle one)
(circle one)
One key source of the reflection of light away from the earth’s atmosphere is atmospheric
aerosols, or collections of particulate matter (tiny solid or liquid particles) that are dispersed and
suspended in the air. Let’s explore the effects of aerosols on Earth’s albedo, by considering the
recent eruption of the Icelandic volcano. As mentioned in the introduction, the volcanic eruption
initially released over 250 million cubic meters of ash. Much of this particulate matter may
remain suspended in the atmosphere, forming atmospheric aerosols. Much of the fine particulate
matter (particulate matter with diameters less than 2.5 um) may remain in the atmosphere for
weeks or months before it settles out.
Aerosols have the ability to reflect incoming sunlight in several ways. Aerosols can
coalesce into raindrops and become constituents of light-reflecting clouds. They are also capable
of reflecting light as individual suspended aerosols in the atmosphere. Now consider the massive
amount of aerosols produced by the Icelandic volcano. With the injection of so much particulate
matter high into the atmosphere, how may the earth’s albedo be affected? How might the ratio of
energy reflect to energy absorbed be affected?
Now you have explored one possible fate of incoming visible light photons: reflection
away from the earth. In topic 4, you will learn about the other primary fate of incoming visible
light: absorption of visible energy and re-emission as infrared energy.
Group activity (university level project)
(As a web-based resource, this group project might be effective if two primary articles were
already linked to the assignment, or if a website link to database was connected. Perhaps the assignment
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could have a list of useful links or pictures beside it that a student could bring up if necessary).
In groups of 2 or 3 students, discuss the effects of volcanic aerosols. Historical records
suggest that slight global cooling may occur in the years following a volcanic eruption. Explore
the reasoning behind this trend by finding 2 primary research articles that discuss the climatic
effects of atmospheric aerosols from volcanoes. Consider how the Earth’s albedo might change in
the years following a volcanic eruption. How does this affect the radiation entering the earth’s
atmosphere? How does this affect the amount of radiation absorbed and used to heat the earth’s
atmosphere? Do all volcanic eruptions have this effect?
Topic 3 Concept Essentials
1. What does the term albedo mean?
2. Based on your results from table 3.1, what might the effect on earth’s surface temperature be
if albedo increased? Decreased?
3. Is the albedo different in various diverse regions of the earth, or is it all constant?
Think: Can you describe three human processes that might reduce the albedo of certain
regions?
4. What role does the reflection of light play in the earth’s overall radiation balance?
Topic 4: Emission of Infrared Radiation
As discussed in Topics 1, 2, and 3, the sun produces radiation mainly in the ultraviolet
(UV), visible (vis) and infrared (IR) regions of the electromagnetic spectrum. When this energy
reaches the Earth, a portion of it is reflected back into space and while the majority of it is
absorbed by the Earth’s surface. The portion of energy that is absorbed heats up the Earth. The
Earth, in turn, radiates energy out into space. As discussed in topic 1, the frequency at which any
object emits radiation depends on its temperature. The Earth, being much cooler than the Sun,
emits energy at a lower frequency– in the thermal infrared (IR) region.
To begin learning about the absorption of incoming solar radiation, open the Earth’s Radiation
Balance visualization. (in a web-based format, this visualization will guide the student through the main
content for topic2- questions are posed so that the student will navigate through the visualization to find the
answers- navigation needs to be added to this visualization). Click on the bottom, left hand panel
entitled “Earth’s Emission of Thermal Radiation”.
Various questions are posed throughout this DLO and repeated in a list below. Take care to work
through the visualization and thoroughly understand the answers to each of the questions posed.
Earth’s Emission of Infrared Radiation DLO Questions
(In web-based format, these questions could be interactive rollovers or popups- or perhaps answer
keys could be available for educators in pdf format)
1.
70% of incoming energy from the sun is absorbed by the earth. What happens to this energy and how
does it affect the Earth’s radiation balance?
2.
3.
How is infrared radiation different from visible light?
What are some reason for the drastic differences between Mars’ and Earth’s climate?
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4.
Consider the radiometer images of earth. When comparing the left image (reflected radiation) with the
right image (emitted infrared radiation), what is noticeable about the areas of reflection and emission?
Are they similar or different?
Now that you have explored how the earth re-emits energy, let’s consider how it affects the
overall radiation balance of the earth. Return to the Planetary Climates DLO and open the Build
a Planet simulator. Use the Earth data below to ‘create’ our planet’s climate.
1) (In the actual visualization , these boxes could be replaced with a screenshot of the 4 boxes at these
positions)
Albedo: 0.36
Greenhouse Effect:
0.44
Distance from the Sun:
1 AU
Surface Temp.: 15’C
(In an interactive, web-based format, the portion of Topic 3 should be done by working interactively back
and forth between the DLO and the lesson)
You can alter the amount of energy emitted by the Earth by changing the surface
temperature value. Try increasing the surface temperature- what is the effect on the total
outgoing energy? What happens if you decrease the surface temperature? Fill in your
observation in Table 4.1.
Table 4.1: Effect of changing temperature on energy balance
(in a webpage format, this table could be done with rollovers or in a printable pdf format for
teachers to print off and use as a worksheet question. Perhaps on the website there could be pdf
files available for teachers with lists of questions or worksheet handouts)
Increased Surface Temperature
Effect on total
outgoing energy
Decreased Surface Temperature
Increased outgoing energy
Increased outgoing energy
Or
Or
Decreased outgoing energy
Decreased outgoing energy
(circle one)
(circle one)
After changing the temperature values, notice that the total energy is no longer balanced.
We know that in reality, earth’s average surface temperature does not vary largely from
15’C, although there are large local variations. What factors are important in keeping a
relatively constant average surface temperature on Earth? In Topic 5, you will learn about
the Greenhouse Effect, a climate factor which plays a vital role in regulating the Earth’s
surface temperature.
Topic 4 Concept Essentials
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1. What type of radiation is primarily emitted by the earth? Why doesn’t the earth emit
visible light and glow like the sun?
Think: Object on earth, such as light bulbs, have the capability of emitting energy. Do
light bulbs emit energy of a higher or lower frequency than the energy that the earth
emits? Can you think of some reasons why light bulbs often feel incredibly hot?
2. What is a mirage?
Think: Many stories that take place in desert regions describe characters in the desert as
going mad and seeing mirages. But perhaps these characters are not actually going
mad!Why might mirages appear more in deserts than in the tundra or in a forest? Why do
we see mirages on some days or in some regions more than others?
Topic 5: The Greenhouse Effect
What first comes to your mind when you hear the about the greenhouse effect? What
would you picture the earth like if there were no greenhouse gases at all in the atmosphere? You
have learned from previous lessons how certain gases are able to absorb radiation and re-emit this
radiation through collisional de-excitation, thus warming the surrounding gaseous molecules.
This topic will focus on the effect that these gases in the atmosphere have on climate. Without the
greenhouse effect, our climate would be completely different!
To review the role of greenhouse gases in our atmosphere, open the Earth’s Radiation Balance
visualization. (in a web-based format, this visualization will guide the student through the main content
for topic2- questions are posed so that the student will navigate through the visualization to find the
answers- navigation needs to be added to this visualization). Click on the bottom, right hand panel
entitled “Greenhouse Gases.”
Various questions are posed throughout this DLO and repeated in a list below. Take care to work
through the visualization and thoroughly understand the answers to each of the questions posed.
Greenhouse Gases DLO Questions
(In web-based format, these questions could be interactive rollovers or popups- or perhaps answer
keys could be available for educators in pdf format)
1.
2.
3.
4.
5.
How is thermal energy ‘trapped’ in our atmosphere?
Why are greenhouse gases so important?
Can Earth’s delicate energy balance change?
What types of gases act as greenhouse gas substances?
Why are do some atmospheric substances act as greenhouse gases while others do not?
This visualization describes how a greenhouse effect is essential to our climate on Earth. To
explore what our Earth would be like without a greenhouse effect, return to the Planetary
Climates DLO and open the Build a Planet simulator. First use the Earth data below to ‘create’
our planet’s climate.
1) (In the actual visualization , these boxes could be replaced with a screenshot of the 4 boxes at these
positions)
Albedo: 0.36
Greenhouse Effect:
Distance from the Sun:
Surface Temp.: 15’C
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0.44
1 AU
(In an interactive, web-based format, the portion of Topic 3 should be done by working interactively back
and forth between the DLO and the lesson)
Now, try simulating planetary conditions where there is absolutely no greenhouse effect
(Greenhouse effect value = 0). How does the radiation balance change?
2) (In the actual visualization , these boxes could be replaced with a screenshot of the 4 boxes at these
positions)
Albedo: 0.36
Greenhouse Effect: 0
Distance from the Sun:
1 AU
Next, try to recreate the radiation balance by changing the temperature. After decreasing
the greenhouse effect, what is the average surface temperature? What does this tell you about our
climate if we had no greenhouse effect?
Now, if you increase the greenhouse effect to 0.75, how is the radiation balance affected?
Change the temperature bar so that the energy in and energy out are once again balanced. What is
the balanced surface temperature with an enhanced greenhouse effect? Fill out your observations
in Table 5.1.
Table 3.1: Effect of changing the greenhouse effect on surface temperature
(in a webpage format, this table could be done with rollovers or in a printable pdf format for
teachers to print off and use as a worksheet question. Perhaps on the website there could be pdf
files available for teachers with lists of questions or worksheet handouts)
Required temperature
change to rebalance
radiation
Increased Greenhouse Effect
Decreased Greenhouse Effect
Increased Surface Temperature
Increased Surface Temperature
Or
Or
Decreased Surface Temperature
Decreased Surface Temperature
(circle one)
(circle one)
Gases produced by human activities can increase the natural greenhouse effect of the
atmosphere. This is often known as the enhanced greenhouse effect. You will continue to explore
the enhanced greenhouse effect in additional lessons.
Understanding how the climate system works, and the likely effects of adding more
greenhouse gases to the atmosphere, are subjects of extensive research by scientists from around
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the world. Better understanding can help to build better models which give more reliable
predictions about the climate of the future.
Topic 5 Concept Essentials
1. Explain why some gases in the atmosphere cause the greenhouse effect.
2. Explain the difference between the natural and the enhanced greenhouse effect.
Radiation Balance Summary
A steady state is reached where the Earth is absorbing and radiating energy at the
same rate, resulting in a fairly constant average temperature. If there were no greenhouse
effect at all then the surface temperature would be about 256K or -17˚C (about the
temperature of a domestic freezer) and life as we know it could not exist because water, the
which is fundamental to life, would be a solid. However, the IR radiation emitted by the
Earth can be absorbed by gases in the troposphere and become trapped. The radiation is
then re-emitted in all directions; some back towards the Earth, which is known as the
‘greenhouse effect’. This leads to an increase in temperature and global warming, making
the average surface temperature of the Earth about 286K or 13˚C. It is an essential part of
keeping our planet hospitable and helps to sustain life. The gases which absorb and then reemit IR are known as ‘greenhouse gases.’
Lesson 4 Concept Review and Questions
(in a web-based format, this type of page with key terms, concept questions, and extension ideas could be available
also as a printable pdf file for teachers)
(in a web-based format, pdf’s will be available with the answers to these questions/group activities for teachers)
Key terms
Topic 1
Topic 2
Topic 3
Topic 4
Topic 5
atmosphere
electromagnetic
spectrum
blackbody radiator
infrared
photon
radiation
radiation balance
visible light
infrared radiation
ultraviolet radiation
albedo
aerosols
particulate matter
radiometer
reflection
blackbody curve
infrared radiation
mirage
thermal energy
absorbance
carbon dioxide
convection
greenhouse gas
greenhouse effect
water
Group Activity
(in a web-based format, this activity might be available as a printable pdf, or as an online tool with
active rollovers or pop-up hints)
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The aim of the following activity is for you to think about some of the complexities
which researchers when modelling climate. The temperature of the Earth, the weather and the
climate are controlled by the energy flowing into and out of the system. Various factors can
affect the energy flow and therefore have an effect on the weather and, in the long term, the
climate. Climate modellers try to understand these changes in order to ensure that their computer
models are accurate.
1) In groups of 2 or 3, consider the effect that increasing the factors in the table below might
have on:
 The amount of radiation from the Sun (mainly light and UV) which is absorbed by the
Earth
 The amount of radiation (mainly IR) being emitted from the Earth.

Many of the answers require careful thought about the underlying chemistry of the atmosphere.
Keep in mind that some factors have clear effects, while others do not have any effect. Review
the DLO’s as a group or refer back to other lessons for answers that you may be stuck on!
2) Group Extension:
If the amount of energy coming into the system is greater than the amount leaving the system,
then the Earth will warm up; the opposite is also true. After filling out the table, consider which
of the 7 factors below will be affected if the Earth warms up? Explain how in each case.
Factor which is increased
1. Water vapour in the
atmosphere (but not as
clouds)
2. Cloud cover
3. Ice/snow cover
4. Dust/aerosols (small
particles) in the atmosphere
5. Amount of CO2 in the
ocean
6. Amount of CO2 in the
atmosphere
Effect on the amount of
radiation from the Sun
which is absorbed by the
Earth
Effect on the amount of
radiation being emitted
from the Earth
Global Climate Change Lesson 4: Energy In, Energy Out
15
Katrina Genuis
7. Amount of plant cover
and photosynthesis
For some of the questions above the answers are well understood by science. Some are
poorly understood and some are variable depending on a large number of other factors. A climate
model can only ever be as good as the information which is fed into it – one wrong assumption
can lead to inaccurate predictions. Climate models (for example those on
www.climateprediction.net) are run using a range of inputs and then tested by using them to
‘predict’ the climate in the past. The closer the model gets to what is known about past climates,
the more accurate it is assumed to be in its projections for the future, although models that are
equally good at reproducing the past might yield very different predictions for the future. It is
important to remember, though, that any projection of the future is based on a number of
assumptions such as how the world might develop, which volcanoes may erupt and how active
the Sun will be amongst others. Modelled climate projections can, at best, tell us how the climate
might change, and what the range of possible future climates is.
Tying it all Together
1.
Think of how the balance between incoming and outgoing radiation affects a
planets climate. Describe, in a paragraph, what Earth might be like with a
dramatically enhanced greenhouse effect. In order for a planet to have an equal
radiation balance with an enhanced greenhouse effect, what is the impact on
temperature? (Hint- perhaps go back to the Build a Planet simulator in the Planetary Climate
applet and try altering the greenhouse effect. How do you have to change surface temperature in
order to create a radiation balance?)
(perhaps in a web-based format, this question could be posed in the format of a table (see table 3.1)
with certain factors changed and options for the effects. Ie- if greenhouse effect is increased, how is
temp affected. If albedo is increased, was is the effect on temperuatreu)
Extension Projects
(in a web-based format, there could be a list of extension research links so that students can easily find the
necessary article or have hints about good sources for their information when doing research).
 Climate Research Extension
Researchers have begun to consider if it would be possible to change Mars’
atmosphere so that the planet is suitable for life. One suggestion is to create a
‘runaway greenhouse effect’ on Mars by anthropogenically increasing the
greenhouse gas concentration in Mars’ atmosphere. Find 2 research papers about
the terraforming of Mars. Write a summary of what the scientists have found.
Then, based on your knowledge of planetary radiation balances, critically review
the scientists proposals and discuss whether you think that terraforming Mars is a
realistic and scientifically sound idea.
 Cultural and Societal Extension
Global Climate Change Lesson 4: Energy In, Energy Out
16
Katrina Genuis
Although Earth as a whole absorbs and emits radiation at a relatively constant
rate, different regions of the earth tend to absorb, reflect, and emit radiation
differently. Consider how different the radiation balance seems at tropical
equatorial regions as compared to a desert region or Antarctica. Research the
climate of two distinct regions of the earth and write a comparison paper about
how human societies in those regions have adapted to specific climatic patterns.
How does the culture, housing, foods, and lifestyle of these groups differ.
Remember to focus on the science; how do differences in radiation and climate
result in these diversities.
 Creative/ Artistic Extension
Draw, paint or sketch an image which demonstrates different aspects or impacts
of the radiation balance on Earth or a different planet. Try to creatively
demonstrate both the unseen and the visible processes that regulate climate.
Consider illustrating the source of incoming radiation, reflection of radiation, the
‘greenhouse’ effect, planetary emission of thermal radiation (heat), or other
factors of a planet’s radiation balance.