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Teacher Prep

Summary of key points:

• Scientists generally agree that data shows that global temperatures have recently been increasing

 
• Scientists agree that increased global temperatures will have a profound impact on our climate

 
• Scientists disagree as to the causes of these recent increases in global temperatures. Some say they are the result of natural processes and changes which have occurred throughout Earth’s history. Others claim that the global temperature increases are the result of human pollution in the atmosphere. No one knows for certain because climate is so complex and our job is to investigate what we would need to know in order to gain more certainty regarding the causes of global warming.

Click on the links below to download lesson plans, teacher resources, and student handouts.
To read the files on your computer, you will need Adobe Acrobat.

 

PART I: How does temperature change?

Summary of key points:

• Temperatures vary by location.

• On a local scale, a single room may have several different temperatures, depending on which part.
• On a global scale, temperatures generally vary by latitude. A number of factors influence temperature, such as the type of surface, the elevation, and proximity to water.

• Temperatures vary by time.

• Some natural processes (such as Earth’s spin on its axis and it’s rotation around the sun) cause temperature to vary at different parts of the day, from day to day, and season to season.
• Other natural processes cause Earth’s temperatures to vary by year, by century, and on 500 and 10,000 year scales. Reasons for these longer variations include:

• Changes in solar radiation
• Lack of volcanoes (which spew ash into the atmosphere thus reducing the solar energy that gets to earth.
• Periodic variations in earth’s orbit (known as Milenkovich cycles)
• And, of course, human activities.

• In order to know if human actions (i.e., "unnatural" processes) are causing global warming, we first need to know that other "natural" processes are causing temperature to change. Once we understand these natural cycles, we can see whether or not current changes depart from the norm.

Click on the links below to download lesson plans, teacher resources, and student handouts.
To read the files on your computer, you will need Adobe Acrobat.

 

PART II: What makes Earth warm?

Revised! Investigation Guide, Part 2 The the next section of the Invesitgation guide used in the previous 2 phases of the project. This brief text gives students their mission for this (the second) stage of the investigation, which is to learn how the climate system works in order to understand what makes Earth warm.  It describes the three main factors that determine temperature: incoming sunlight, the reflection and absorption of sunlight on Earth’s surface, and the role that the atmosphere plays in absorbing energy.  There is an emphasis on the atmosphere, since it is the factor which humans have the most control over (through the emissions of greenhouse gasses such as carbon dioxide. Note: If you plan to skip the Pen light lab (C3) in the interest of time, then you may wish to either inform students that you will not be investigating the role of incoming sunlight, or you might conduct your own brief overview of how the angle at which sunlight reaches Earth determines the intensity of that light (thus, the equator receives the most direct sunlight and thus the most intense light and the most energy per area, while the poles receive the most indirect sunlight and thus the least intense light and least energy per area.  See the lesson plan for more teacher notes on this subject matter.   Optional. Letter from the Secretary General of the "League of Nations" (letter provided above) A narrative introduction to Part 2 designed to introduce roles and tasks and motivate students	Introduction
C3. Pen Light Lab: The sun's rays This lab illustrates how light intensity from the sun varies based on the angle at which it hits Earth’s surface. This is particularly important to understanding why temperatures vary by latitude: the equator receives direct sunlight, whereas the sunlight light reaches higher latitudes is less direct. Less direct sunlight is less intense, explaining why higher latitudes receive less incoming solar energy. While this lab helps explain what makes Earth warm, it is considered "optional" to our investigation of global warming because the Earth-Sun relationship is not something human actions are likely to affect. Teacher resources:Angle measurement templates Student handouts:Lab sheet	Sun
C4. WorldWatcher Activity: Where does Earth's heat come from? (whole-class or in groups) This WorldWatcher activity can be done in small groups at computers or as a whole-class discussion using either transparencies or an LCD projector attached to a computer. The purpose of this activity is to see that while Earth receives consistent amounts of solar energy at each latitude (due to the even spin of the globe on its access), surface temperatures do not follow such an even pattern. By allowing students to compare visually the uniformity of an incoming solar energy visualization (represented in even bands of colors) to the lack of uniformity of surface temperature (choppy bands of colors), students begin to consider other forces besides incoming solar energy (such as weather systems, ground cover, the oceans, elevation, and so on) which must be at work that determine the heat we feel on the surface. This is a set-up for activities C5 & C6, which explores the role of the surface in absorbing different amounts of energy. Teacher resources: Activity sheet (with notes) Picture of Incoming Solar Energy WorldWatcher Visualization Picture of Surface Temperature WorldWatcher Visualization   Student handouts:Activity sheet	Sun
C5. Reflectivity Lab: Which colors absorb the most energy? This lab explores how different colored surfaces absorb and reflect different amounts of energy. By placing different colored envelopes under a heat lamp and measuring their temperatures, students learn that lighter colors tend to reflect light while darker colors tend to absorb light (and thus retain more energy). This is important to understanding what happens to sunlight when it reaches the earth. Student handouts:Lab sheet	Surface
C6. WorldWatcher Activity: What happens to sunlight on Earth? Building on C5, this activity explores solar reflectivity and absorption on a global scale. By exploring datasets which show the reflectivity of the earth’s surface, students learn about how different types of ground cover reflect and absorb different amounts of solar energy. This helps to explain how different parts of the world interact with the sun and how climate varies because of it. Student handouts:Activity sheet	Surface
C9. Greenhouse Gas Lab: Measuring the heat absorption of carbon dioxide Carbon Dioxide is identified as "greenhouse gas" because of its ability to trap heat within earth’s environment. This investigation is designed to compare the ability of a sample of carbon dioxide gas to absorb thermal energy compared to a sample of air. Through this experiment, students will have the chance to build a visual representation of the greenhouse effect by witnessing how carbon dioxide absorbs and retains heat more than plain air. The experiment illustrates the heat-absorption of atmospheric carbon dioxide. It is recommended that students read the handout explaining "What are the greenhouse gasses." Revision note: As a variation on the existing lesson plan, measure the flasks of trapped carbon dioxide and plain air during both their warm-up and cool-down phases. By adding the measurement of the cool-down phase to the lab procedure, you will better witness the role that CO2 plays in retaining energy. Teacher resources: Background reading: The Greenhouse Effect and Global Warming Background reading: What is the Greenhouse Effect? Background reading: What are the Greenhouse Gasses? Student handouts: Lab sheet Blank graph	Atmosphere
A3. Why is average temperature greater on Venus than on Mercury? This activity is designed to demonstrate the effects of that atmosphere plays in maintaining temperature (known as the "greenhouse effect"). Students compare Venus, which has a thick atmosphere and fairly consistent day and night temperatures and Mercury, which has no atmosphere and temperatures ranging from very hot during the day to very cold at night. This comparison is a clear illustration of the role that atmospheric gasses (such as H2O and CO2) play in warming planets. Teacher resources: venus picture mercury picture	Atmosphere
C8. WorldWatcher Activity: What would temperature on Earth be without the greenhouse effect? This activity, designed for shock effect, shows students what temperature on earth would be like without the greenhouse effect. Targeting a common misunderstanding that the sun is mostly responsible for maintaining comfortable surface temperatures, students see a chilling dataset (both literally and figuratively!) showing the surface temperature that results solely from the energy absorbed from the sun. Realizing that this is not enough energy to sustain life on earth, students are left to wonder what other factors contribute to the temperatures we are used to (e.g., the greenhouse effect). Teacher resources: Background reading: Is the Greenhouse Effect Good or Bad? Student handouts: Activity Sheet	Atmosphere
New! Carbon Cycle Activity This is an online activity investigating the carbon cycle (as well as an optional activity on the water cycle) are available at: http://www.letus.northwestern.edu/projects/gw/cycles.html The activity sheet is provided in this packet, but you will need to go online to experience the activity. In a previous activity, we noticed that carbon dioxide concentrations have increased over the past 100 years to levels never seen before. But where does this carbon dioxide come from? The fact is, Earth has always contained more or less the same amount of carbon molecules. Therefore, we know that the carbon now in the atmosphere had to exist somewhere on Earth before becoming a greenhouse gas, but where? In this activity you’ll have the chance to investigate many of the ways in which carbon travels throughout earth ecosystems. This will be done by following one carbon molecule, "Carbo", through what we call the carbon cycle.	Atmosphere
D3. WorldWatcher Activity: Investigating population and carbon emissions In this activity, students look at a carbon emissions dataset to see which nations emit the most carbon per year. They then compare this to a dataset of population density, noting which areas have the densest populations as compared to the areas which emit the most carbon. Students learn that while many countries emit large amounts of carbon per year, some of these countries (such as China & India) have dense populations while others (such as the United States) have sparse populations. This leads to discussion of the difference between "total carbon" emissions versus "carbon per person". As a result, students learn which countries pollute the most per capita. Optionally, students examine an additional visualization that shows carbon emissions divided by population density to see directly which countries emit the most pollution per person. Student handouts: Activity sheet (option A): Investigating Population & Carbon Emissions Activity sheet (option B): Investigating Population & Carbon Emissions Carbon emissions by country graphs Carbon emissions by country worksheet	Atmosphere
New. Supplemental Resource: Sources of Carbon Dioxide In this "pie chart" shows the different sources of human-made carbon dioxide and provides some important facts about these sources. It is intended as a supplement to the previous activity. Resource: Sources of Carbon Emissions	Atmosphere

Summary of key points:

• There are three primary factors responsible for making Earth warm: incoming solar energy, the reflection and absorption of that energy on Earth’s surface, and the reflection and absorption of that energy in the atmosphere.

 
• Some sunlight never reaches Earth because it reflects off clouds back into space.

 
• Light colored surfaces reflect more energy, while darker colored surfaces absorb more energy. This explains why deserts usually are cool at night (the sand absorbs little energy) and why an asphalt parking lot remains warm long after the sun goes down.

 
• The atmosphere plays a crucial role in trapping energy that radiates off Earth’s surface, acting as a "blanket" which keeps heat in. We call this process the "greenhouse effect". Without the greenhouse effect, Earth would be too cold to sustain life as we know it. However, scientists are concerned that, by adding too many gasses to the atmosphere, we are creating an "enhanced" greenhouse effect which could lead to global warming.

 
• Carbon dioxide, water vapor, methane, and nitrous oxide are some examples of greenhouse gasses. Scientists are most concerned with carbon dioxide, since it is the gas humans are adding to the atmosphere in the greatest quantity.

 
• Carbon dioxide molecules, like all greenhouse gasses, absorb energy. Therefore, air which has a large quantity of greenhouse gasses will retain energy for a longer period than "normal" air. This is why scientists suspect that carbon dioxide increases are related to temperature increases.

 
• Venus is an example of a planet with an extreme greenhouse effect (consistent temperature). Mercury is an example of a planet with no greenhouse effect (very hot by day, very cold by night).

 
• There is roughly the same amount of carbon on Earth now as there has ever been. Humans don’t "add" new carbon to Earth’s system. Rather, processes such as burning fuel or eating & breathing cause a carbon "transfer" from solid form (e.g., food, gasoline) to a gas form (e.g. carbon dioxide).

 
• Certain areas with highly developed economies, such as the U.S. and Europe, are responsible for the highest amounts of carbon emissions per person. Other nations with high carbon emissions, such as China and India, also have high populations, which means a lower amount of emissions per person.

Click on the links below to download lesson plans, teacher resources, and student handouts.
To read the files on your computer, you will need Adobe Acrobat.

 

PART III: Addressing Climate Change

Summary of key points:

• If climate change is for real, it will impact different parts of the world differently. For example, while "global warming" means an average increase of Earth's temperatures, some places may actually experience colder temperatures in the future. Also climate changes may affect precipitation patterns, meaning for example that areas which have been good for farming may experience drought and other areas which have been unfarmable may become more fertile.

• Different nations have very different concerns regarding the possible impacts of global warming. For example:

• Nations with large coastal populations may fear the effects of sea level rises or more extreme weather.
• Some nations rely on agricultural practices which emit large amounts of greenhouse gasses?for example, rice farming in East Asia produces a large amount of methane. These countries might be unwilling to reduce their production since their citizens rely on rice for their survival.
• Some nations have extensive forests, while others have little forest. Forested nations might claim that they are entitled to emit more carbon dioxide since their forests play such a large role in removing carbon dioxide from the atmosphere.

• While there are many ways to address the risks of global warming, most of these solutions come with high economic costs. Job losses and higher prices for goods are but two examples.

• Nations with developing economies are opposed to solutions which freeze carbon dioxide emissions at current levels. They fear that doing this would prevent them from expanding their economies and creating a more comfortable quality of life for their citizens. They resent industrialized nations who, having polluted the atmosphere for years, now want to freeze things the way they currently are.