Eunit

Eunit - PLT Curriculum Pilot

Climate Time Machine — Enrich

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Option 1:  Invite students to imagine a world where the temperature is five degrees higher than now, and predict what would happen in the region they studied.

Option 2: Have students locate the Arctic on a map or globe, and then explore changes in Arctic sea ice over time using PLT’s Arctic Sea Ice data sheet. See the National Snow and Ice Data Center website for an interactive graph of sea ice.

Option 3: Participate in Project BudBurst, a citizen science program collecting data about the effects of climate change. Look for and report the timing of different plants’ first leaf, first flower, and first fruit each year.

Option 4: During late winter or early spring in colder climates, have students observe a lake to determine what date the ice breaks up (this is known as “ice-out”). Have your students investigate historical data on “ice out” dates in your community and compare them with the date for this year. Continue collecting the data each year.

Option 5: Use an interactive tool called EarthViewer to watch Earth’s continents shifting over deep time, and explore the tool’s layers to view changes in atmospheric composition, temperature, biodiversity, day length, and solar luminosity.

See Additional Resources for more ideas to enrich this activity.

Climate Time Machine — Doing the Activity

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Engage

  1. Engage students in the topic through one or more activities:
  • Bring in a guest speaker on climate or geologic history.
  • Show a brief video on  ice ages or glaciers, on the geologic history of the region students will study, or on extinct animals from the last ice age (see Additional Resources for this lesson).
  • Do a quick hands-on demonstration of glaciers, such as adding ice to water and discussing how melting ice changes the water level, or using a stream table (such as depicted) to show the movement of a river versus a glacier.

    Black and white illustration of two stream stables set up side-by-side

    Stream tables can be used to model the differences between how rivers and glaciers interact with the landscape.
    Source: Project Learning Tree’s PreK-8 Environmental Education Activity Guide, Activity 44: Water Wonders

  • Take a field trip to a local museum or geologic site.
  • Contact a local university, historical society, or geological agency for additional possibilities.
  1. Share the Letter from the Museum Director student page, which invites students to create an exhibit on historical climate patterns as a way to learn about current global patterns. (Note that you may choose to have students focus on the Great Lakes or another region. More Great Lakes resources can be found in the Additional Resources for this lesson.) Introduce the project’s driving question: What can we learn from studying climate history that will help us understand current global temperature trends? Explain that students will have the opportunity to research and create a museum exhibit, slide, presentation, website, or other product such as a poster, article, or brochure that will accurately address the question.

Explore

  1. Put students into groups of four. You can either assign the roles described on the Climate Science Project Planner student page, have students draw them from a bowl or hat, or let the students self-select their roles once they are organized into groups.
  1. Have students re-read the Letter from the Museum Director student page within their groups to identify what they know and what they need to know in order to do the project. They may record these items in their journals using a T-chart (as in the illustration). Be sure students begin by first writing the driving question to guide their thoughts.
Driving Question:
What We Know What We Need to Know
 

 

 
Male student is writing his descriptions to for his Great Lakes project on a large sheet of white paper.

A student fills out a T-chart about climate change to share with the class.
Photo credit: Renata Walshak

Encourage students to be as thorough as they possibly can identifying this information.  As students discuss what they need to know, you may want to prompt them with important topics they may overlook. Possible questions they may have include:

  • What is climate change?
  • What caused the ice ages?
  • What climate data is available?
  • What is the concern about carbon dioxide in the atmosphere?
  • What changes can happen to an ecosystem if it gets warmer?
  1. Copy the T-chart structure onto the board. Ask groups to share what they identified in each category and openly record their responses. Start with what they know before moving to what they need to know. Focus particularly on the What We Need to Know category, as this will help you understand what content the students may need help on and procedural questions they have. If a particular point or question requires more than a short answer from you, tell the students when it will be addressed in class.
  1. Share the project timeline with students (see Getting Ready), and together go over the Climate Science Project Planner student page describing the project, making sure that students understand their task. Also review the Climate Time Machine Evaluation Rubric student page, which identifies expectations for their work.
  1. Provide students with style guidelines for citing sources and for creating a bibliography (for example, see Purdue University’s Online Writing Lab).

Explain

  1. Have the students from different groups with the same roles meet together to discuss what they need to do and what to research. If possible, facilitate each role’s meeting, allowing students to decide on the specifics, but prompting them as needed. You may also help them to determine ways to gain the information, such as through stations or labs, computer research, or journal references. After the role meetings, have the original groups gather again to coordinate their tasks.
  1. Allow students time to research the information related to their role. Depending on your class, their research may occur in the library or computer lab, individually or in groups, or as homework.
  1. Check in with students periodically to help keep them on task. You may want to have students record research notes in their journals and submit them regularly for your review. You might also consider grading students on the completeness of the work at certain project check points. Be sure that students do not go astray as they are researching: it is easy for them to get too much information and become overwhelmed. Ask prompting questions to refocus their search.
  1. After their research is complete, have students share what they have learned in their expert roles with the others in their group.

Elaborate

  1. Three student show their Great Lakes Past and Present display.

    Students present their project on the Great Lakes.
    Photo credit: Lindsey Steblen

    Have groups work together to develop a plan for their exhibit, making sure that all group members contribute to the product and are familiar with their project content. If possible, have groups review one another’s plans to provide ideas and feedback. Encourage students to be creative in presenting the information, including maps and visuals as appropriate.

  1. Remind students of the project timeline and their deadlines for creating and presenting the exhibits.
  1. Allow at least one to two class periods for students to create their exhibits and to share them with the class.

Climate Time Machine — Background

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For the Teacher

The interaction of climate and geology helped sculpt and form our present-day landscapes. As the climate has changed through Earth’s history, the landscape has changed with it. Although you may study this change in any location you choose, one of the best areas to study it is the Great Lakes region of the United States. This area has molded and melded into the five lakes we know today as global temperatures warmed from a freezing ice age over time.

The Great Lakes were formed nearly 20,000 years ago when the Earth’s climate warmed and the last glacial continental ice sheet retreated1. The glacier, up to 2 miles thick, was so heavy and powerful that it gouged out the Earth’s surface to create the lake basins. Meltwater from the retreating glacier filled the newly created basins. Approximately 3,500–4,000 years ago, the Great Lakes attained their modern levels and area.

Timelapse images of the formation of the Great Lakes over the last 14,000 years

The Great Lakes were formed over the course of thousands of years as the glacier retreated.
Source: About Our Great Lakes. National Oceanic and Atmospheric Administration (NOAA) Great Lakes Environmental Research Laboratory. Originally from Living with the Lakes. U.S. Army Corps of Engineers and the Great Lakes Commission. 1999.

This dynamic region is an ideal place to study past and present climatic changes, and to make predictions for future climate change. However, feel free to have students examine your local area or other region. For more information about geological changes in the Great Lakes Region, check out the websites listed in Additional Resources for this activity.

This activity is designed as a project-based learning activity, a teaching method in which students gain knowledge and skills by working for an extended period of time to investigate and respond to a complex question or challenge. Most projects begin with a driving question—an open-ended question that sets the stage for the project by creating interest and curiosity.

With this classroom strategy, the activity is primarily student-led. The teacher’s role is to be a facilitator of knowledge, not the leader, content expert, or project director. There are several strategies for providing content resources for students, such as stations, expert group members, books, and note pages. For more information and resources on project-based learning, see the Buck Institute for Education website.

This is a cross-curricular project, incorporating science, social studies, and English language arts. Consider partnering with other teachers in these areas for help and support.

Formative assessments can be used whenever you feel they are appropriate throughout the course of this activity. You might conduct assessments at these points:

  • After students have identified what they know and what they need to know for the project (steps 4 and 5)
  • After expert groups have shared their research (step 11)
  • During the time students are working in their project groups (steps 12–14).

As a general rule, the more time students are given to complete this activity, the more assessments should be incorporated to check on student comprehension and knowledge gain.

 

Is It Only Natural? — Tools

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Student Pages

Is It Only Natural? — Teacher Resources
Is It Only Natural? — Evaluate
Is It Only Natural? — Tools
Is It Only Natural? – Additional Resources
Is It Only Natural? — Enrich
Climate Change Stations
Carbon & Climate – Google Classroom Student Pages
Is It Only Natural? — Doing the Activity
Is It Only Natural? — Background
Is It Only Natural? — Overview

Teacher Pages

Is It Only Natural? — Teacher Resources
Is It Only Natural? — Evaluate
Is It Only Natural? — Tools
Is It Only Natural? – Additional Resources
Is It Only Natural? — Enrich
Climate Change Stations
Carbon & Climate – Google Classroom Student Pages
Is It Only Natural? — Doing the Activity
Is It Only Natural? — Background
Is It Only Natural? — Overview

Additional Resources

Is It Only Natural? — Teacher Resources
Is It Only Natural? — Evaluate
Is It Only Natural? — Tools
Is It Only Natural? – Additional Resources
Is It Only Natural? — Enrich
Climate Change Stations
Carbon & Climate – Google Classroom Student Pages
Is It Only Natural? — Doing the Activity
Is It Only Natural? — Background
Is It Only Natural? — Overview

Is It Only Natural? — Teacher Resources

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lesson-3-teacher-resource

Climate Change Station Cards


(Cut cards apart.)

Station 1: Earth’s Wobbling

What to Do

Get a penny and spin it. Watch it as it moves around on the table top. Notice while it is spinning, it will wobble. The Earth also spins on its axis like a top. It takes the Earth 24 hours to spin one time around, and we call this a day. The Earth can sometimes wobble in its orbit around the sun. This slight wobble can change the amount of solar radiation certain latitudes will receive. This can be one natural cause for cooling or warming of the Earth’s atmosphere.

Station 2: Changes in the Earth’s Orbit

One of the biggest misconceptions of the causes of seasons deals with the shape of the earth’s orbit. Many textbooks show the orbit as an elongated oval when in reality it is almost a circle. When the Earth is closest to the sun it is 91,400,000 miles away. When the Earth is farthest away it is 94, 500,000 miles away.

What to Do

Look at the illustration. Use a rule to measure the distance from the sun to the Earth for each of the four dates. In the geologic past the shape of the Earth’s orbit has varied slightly, increasing or decreasing the distance from the sun. This caused cooling or warming due to changes in incoming solar radiation.

Station 3: The Tilt of the Earth’s Axis

Throughout Earth’s history, the angle of the tilt of the Earth has changed from its present day angle. This affects the amount of solar radiation the surface receives and can change temperatures.

What to Do
  1. Look at the globe on the stand. It is tilted because the Earth is tilted about 23.5 degrees in relation to the sun. Turn the globe so that the axis is pointing away from you. Keep it in this position for the rest of your time at this station.
  2. Pick up a flashlight and shine it on the 30 degrees North line of latitude. Notice how the light spreads across the surface of the globe.
  3. Now, with the axis still facing away from you increase the tilt of the Earth by slightly moving the top of the globe away from you around an inch. Have your partner put the light on the globe in the same spot. Describe how the light spreads across the globe.
  4. Finally tilt the axis of the globe towards you slightly about an inch. Have your partner shine the light on the same location. Describe how the light spreads across the globe.

Station 4: Reflection of Sunlight

A change in the amount of solar radiation that is reflected back into space will cause the Earth’s surface to either heat or cool off.

What to Do
  1. Get the mirror and flashlight. Hold the flashlight around 12 inches at a slight angle directly above the mirror. Describe the reflection of light.
  2. This reflection represents what happens to incoming solar radiation when you have particles such as water droplets, or volcanic ash in the atmosphere. The amount of solar radiation reaching the Earth’s Surface is decreased. This can cause a decrease in temperatures.

Station 5: The Greenhouse Effect

Earth’s atmosphere works like a blanket, holding in the sun’s radiant energy. Without this “greenhouse effect,” more energy would escape into space, causing the Earth to become colder.  When certain gas levels increase in the atmosphere they keep excess heat in the atmosphere. This throws off the radiant balance, which can lead to a warming of the climate. At times during Earth’s history, volcanic eruptions increased greenhouse gases, trapping the radiant energy.

What to Do
  1. Observe the greenhouse effect set-up. Read the temperature of the thermometer in the clear sealed container. This represents a greenhouse, with the walls representing gases trapping the radiation. Record the temperature.
  2. Read the temperature of the thermometer in the unsealed container. This represents the atmosphere without increased gases trapping the radiation.
  3. Compare the two temperatures. Which set-up represents increased solar radiation and which one represents less?

Station 6: The Position of the Continents

Earth used to have just one large supercontinent that eventually broke up into the continents we know today.

What to Do
  1. Place the cutouts of the continents as one large supercontinent as they looked in the past (below). Consider how the position of the continents would affect ocean currents and the amount of radiant energy absorbed by the land and water. Write a statement describing how this might affect the Earth’s climate.
  2. Now slowly move the continents to their present day position. As the continents have moved, ocean currents, global wind patterns and radiant energy absorption have changed. Write a statement describing how this change might affect the Earth’s climate.

Teacher Page

Continents Cutouts

Print on cardstock or paper, and cut out around the continents.

Is It Only Natural? — Evaluate

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Option 1: 

Quiz: Activity 3—Is It Only Natural?

– After finishing the activity, have students complete this 5-question quiz to check their understanding. The quiz asks questions about the factors that can affect Earth’s climate.

To grant students access, simply provide them with this abbreviated, case-sensitive link: http://bit.ly/IsItOnlyNatural.  For troubleshooting tips, visit the Carbon & Climate Introduction or Technical Support page.

Example of student poster including graph of the data and arguments

An example of a student poster with a graph of their data and their arguments.
Photo credit: Mary Servino

Option 2: Use students’ posters from the activity to assess their understanding of the concepts.

Option 3: Challenge students to examine the data they have collected and to construct an argument related to present day climate change with the Constructing an Argument student page as a guide. Be sure that students understand the elements required in their argument, including claim, evidence, and reasoning (see the Background for more information). Use a rubric, such as the Is It Only Natural? Evaluation Rubric teacher page, to assess their work.

Is It Only Natural? — Overview

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Students will explore various factors that have caused climate change in the past, analyze carbon dioxide levels over time, and construct a claim, supported with evidence and reasoning.

Note: Before doing the Explore portion of the activity, students should know that seasons are caused by the orientation of the Earth’s axis in relation to its orbit around the sun. You may want to introduce or refresh their understanding of this concept by modeling it with a lamp and a globe.

Learner Objectives

  • Students will summarize past causes of global climate change in Earth’s history.
  • Students will analyze data trends and interpret evidence of the factors that have caused the recent rise in global temperatures.
  • Students will create a claim substantiated by evidence and reasoning.

Materials

  • Climate Change Stations teacher page, printed on cardstock
  • Copies of Changes in Earth’s Climate, Causes of Climate Change, and Constructing an Argument student pages, one per student
  • Copies of Mauna Loa Data student page (optional)
  • Materials for stations: spinning top, rulers, globe on a stand (12-inch or similar), 2 flashlights (with a directed beam, such as LED flashlight or smartphone flashlight), 1/2 inch (1 cm) wedge,  small mirror, piece of translucent plastic (such as a plastic cutting board or a take-out container lid), battery-operated flickering candle, cardboard box (large enough to hold candle), two clear 2-liter bottles, 2 thermometers (long enough to fit in 2-liter bottles), utility knife, plastic wrap, soil, light source (optional), tape, 2 large rubber bands
  • Double balance scale (optional)
  • Cardboard scraps (optional)

Time Considerations

  • Getting Ready: 60 minutes
  • Doing the Activity:  Three to five 50-minute periods
  • Evaluate: Varies, depending on option selected

Getting Ready

  • Make copies of the teacher page and student pages.
  • Using the suggested list in the Additional Resources for this activity, identify suitable websites for students to get current data on atmospheric carbon dioxide levels. You may want all students to use one source or have them use different sources to see fluctuations by geographic area.
  • Set up each of six stations as follows. Note that, depending on your class, you may choose to do the stations as demonstrations.
    • Station 1: Place the station card and the spinning top at the station.
    • Station 2: Place the station card, the globe on a stand, one ruler, one of the flashlights, and the wedge at the station.
    • Station 3: Place the station card, the globe on a stand, one of the flashlights, and the wedge at the station.
    • Station 4: Place the station card, small mirror, piece of translucent plastic, and the other flashlight at the station.
    • Station 5: Place the station card, battery-operated flickering candle, and cardboard box at the station. Depending on the box, cut a hole if needed so that students can observe the candle in the box. (The box simply provides a dark area for observing the candle flame.)
    • Station 6: Place the station card at the station. Create two different greenhouses for the station as in the illustration below.
      1. Cut the tops off each bottle with the utility knife and fill them with equal amounts of soil.
      2. Set a thermometer inside each bottle where it can be easily read, then tape the thermometer to the inside of the bottle, facing out (you may need to use some small scraps of cardboard to help keep the thermometer steady). Each thermometer bulb should be about an inch above the soil.
      3. At least an hour before class, cover one of the bottle openings with plastic wrap, securing it with a rubber band. Partially cover the other bottle with plastic wrap and secure it with another rubber band,  and place both bottles in intense sunlight (or near a light with a high wattage bulb).A3ExampleExperimentSetUp
  • See Additional Resources to find other supports for teaching this activity.

PLT Conceptual Framework

  • 3.11. Effective decision-making involves a careful study of all sides of the issues, along with the ability to differentiate between honest, factually accurate information and propaganda.
  • 5.0. Structures and systems may be stable and yet change over various periods of time.
  • 5.3. Ecosystems change over time through patterns of growth and succession. They are also affected by other phenomena, such as disease, insects, fire, weather, climate, and human intervention.

Standards

See Standards Connections in the Appendices for a list of standards addressed in this activity.

Is It Only Natural? — Doing the Activity

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Engage

  1. Ask students if they know how a budget works. Point out that with a balanced budget, the same amount of money goes in and comes out. (Optional: Use a double balance scale to represent a balanced budget and show what happens if you add or subtract weights.)
  1. Explain that many things in nature operate in a manner similar to a budget, including the balance of radiant energy from the sun coming into and leaving the Earth’s system. If the Earth’s radiant energy budget becomes unbalanced, it can cause the climate to heat up or cool down. Point out that throughout the Earth’s history, there have been times of colder or warmer climates.
  1. Ask students what an ice age is. Discuss what might happen in the Earth’s budget in order for an ice age to occur.
  1. Ask the students what they hear about the Earth’s radiant energy budget today. Answers will vary, but most will say it is out of balance, meaning the Earth is retaining more heat then it loses. Remind students that in looking at changes to the Earth’s radiant budget, we aren’t just looking at the past year, but at the pattern over many, many years. Invite students to write in their journals what they think may be the cause of these changes.
Two female students shine a flashlight at a globe. These students are observing wear the light can be seen on the global and how the movement of the earth changes this light.

These students at Station 3 are learning about how changes in tilt of the Earth’s axis can affect climate.
Photo credit: Ann Smart

Explore

  1. Explain that students will be looking at some of the natural ways the Earth’s energy budget has been altered in the past, leading to changes in the climate.
  1. Divide the students into small groups, and give them time to visit each of the stations. For each, they should conduct the activity described on the station card, and complete that section of the Changes in Earth’s Climate student page.

Explain

  1. Invite each group to share the key points they included in their answers to each of the “What Do You Think?” questions.  Possible correct answers include:
    • Station 1 – The Earth’s wobble doesn’t affect the total amount of solar energy received by the Earth, but it does affect which part of the Earth receives more of it. Depending on the angle, the wobble can alter the intensity of the seasons in one hemisphere compared with the other.
    • Station 2 – In periods when the Earth’s orbit is more oval, there are greater fluctuations between seasons as the Earth is closer or further away from the sun at different times of the year. But the average solar energy the Earth receives over the course of a year is the same.
    • Station 3 – When Earth’s tilt changes, the seasons can become exaggerated. More tilt means more severe seasons—warmer summers and colder winters; less tilt means less severe seasons—cooler summers and milder winters.
    • Station 4 – Erupting volcanoes emit ash and other particles into the atmosphere, which cause more of the sun’s energy to reflect back into space. This can cause an overall decrease of global temperatures for a period after the eruption.
    • Station 5 – Changes in the brightness of the sun due to sunspots can influence Earth’s climate from decade to decade. This can lead to slightly cooler temperatures.
    • Station 6 – Higher levels of CO2 and other greenhouse gases increase the greenhouse effect. This makes the Earth warmer, affecting Earth’s overall temperature and weather patterns worldwide.
  2. Share with students the Causes of Climate Change student page, pointing out the different elements of the graph. Invite them to discuss in their groups what conclusions they can draw from the graph. Ask volunteers to share from their group’s discussion.
  1. Conduct a formative assessment by asking students to reflect on what they have learned about the past causes of global climate change, and to write one or two paragraphs about it in their lab notebook or journal.

Elaborate

  1. Explain that most scientists today believe that extra carbon dioxide and other greenhouse gases in our atmosphere are speeding up a natural warming trend. Explain that students will have the opportunity to explore and analyze carbon dioxide data. They will then decide which explanation for climate change they support and prepare an argument (with claim, evidence and reasoning) justifying their position.
  1. Ask students to name some of the gases that are found in air (nitrogen, oxygen, argon, carbon dioxide, and rare gases such as helium, neon, and radon). Ask them what percentage of air they think nitrogen, oxygen, argon, and carbon dioxide (CO2) make up. (Air is about 78% nitrogen, 20% oxygen, 0.9% argon, and 0.03% carbon dioxide. Rare gases, including helium, krypton, neon, xenon, and radon together make up 0.09%. You may want to share a graph, such as the one below, of the composition of air.) Explain that students will be examining the concentration of carbon dioxide in the atmosphere over time.

    pie chart of atmospheric air composition

    Air is composed mainly of nitrogen and oxygen, with small amounts of other gasses.
    © American Forest Foundation

  2. Tell the students that they will visit several different websites, looking for the relationship between increased atmospheric carbon dioxide levels and average air temperatures. Share the links to the websites you have identified as being suitable for your students (see Getting Ready.) Students will need to cite each website they use. If possible, they should copy the graphs they use comparing carbon dioxide and temperatures. Have the students visit as many sites as time permits. (Note: If Internet access is limited, you may choose to have students use data included on the Mauna Loa Data student page.)

    Three female students complete the tasks at the orbit climate station.

    Students at Station 2 record the results of their measurements. Photo Credit: Ann Smart

  3. After they research carbon dioxide data, have students make posters summarizing the data they found. They can include both text and any graphs or data they referenced. They may also choose to organize their posters into four quadrants: Question, Claim, Evidence, and Reasoning.
  1. Discuss:
    • What pattern do you notice in the graphs?
    • What pattern do you notice within each year? What could potentially cause this pattern?
    • What factors might contribute to these patterns?
    • What do you predict the CO2 concentration will be in the year 2020? What assumptions did you make to arrive at this prediction? What impact might this have on climatic conditions?

 

Is It Only Natural? — Background

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The Earth’s climate system is very complex. It is affected not only by what happens in the atmosphere (gaseous area surrounding Earth), but also in the oceans, the cryosphere (glaciers and ice caps), the geosphere (land areas), and the biosphere (area with living organisms). The interaction of these systems is difficult to predict. Understanding the changes in the Earth’s climate is one of the biggest questions facing scientists today.

Over the 4.5 billion years of Earth’s existence, its climate has changed many different times. These changes are evident in the fossil record and in other records, such as ice cores. Several factors have contributed to climate change in the past. These include wobble in the Earth’s axis; variations in the Earth’s orbit and tilt; solar output; volcanic gases and ash in the atmosphere, which affect the sun’s reflection off the Earth’s surface (called the albedo effect); and changes in land masses due to plate tectonics. As a result of these factors, Earth has had five major ice ages in the past (see Figure 1), as well as times when there were no frozen poles. For more information about each of these factors, see NASA’s Climate Science Investigations: Causes of Climate Change.

Graph of Ice Ages during the past 2.4 billion years

Figure 1. Records from the past show the major ice ages in the Earth’s history.
Source: Ice Ages: What Are They and What Causes Them? Utah Geological Survey.

Carbon dioxide (CO2), nitrous oxide (N2O), methane (CH4), and water vapor (H2O) are sometimes referred to as greenhouse gases. It is important to remember that these compounds are a natural part of the atmosphere. In fact, they are necessary to support Earth’s biosphere. These gases (along with others) let in ultraviolet radiation given off by the sun but prevent some of the infrared radiation that is emitted by the Earth from leaving the atmosphere, similar to the way that the glass panes of a greenhouse trap heat. Without this heat-trapping mechanism—called the greenhouse effect—the planet would be too cold to support life.

Greenhouse Effect diagram

© Project Learning Tree

The concentrations of many greenhouse gases have fluctuated during the history of the planet. However, air samples from ice cores representing the past several thousand years indicate that CO2 levels in the earth’s atmosphere have been fairly stable at about 280 parts per million (ppm). Those levels started to rise at the start of the Industrial Revolution, around 1860. By 1958, atmospheric CO2 levels reached 315 ppm. In 2014, CO2 levels topped 400 ppm for the first time in over 800,000 years.

Carbon dioxide levels go through an annual cycle. Every spring, when plants start growing aggressively, they take up CO2 and the levels drop until the fall. In the fall, the levels of atmospheric carbon dioxide begin to rise again as leaves die and decay.

According to National Oceanic and Atmospheric Administration (NOAA) scientists, there are other natural fluctuations in climate that influence the carbon balance. Oceans and soils take up and release CO2. Other events like volcanic eruptions and El Niños can impact CO2 levels. The recent increases are beyond what is historically considered normal (or natural) levels. Many believe that this increase is already changing the Earth’s climate.

Most increases in carbon dioxide emissions come from burning fossil fuels to run automobiles, power plants, and industries. The second largest source is land-use change, mainly the clearing of forests for agriculture or development. In the 19th and early part of the 20th century, land-use change actually contributed more to greenhouse gas emissions than fossil fuel combustion. Today, this order has flipped dramatically, with approximately 80% of carbon dioxide emissions attributed to fossil fuel combustion. This switch is mostly because our fossil fuel use has increased dramatically, but also because in some areas such as the northeastern United States, abandoned agriculture fields have reverted to forests, re-absorbing some of the CO2 that was emitted 100 years before.

In 2013, total global CO2 emissions reached approximately 40 million metric tons, 61% higher than 1990 (the Kyoto Protocol reference year) and 2.3% higher than 20121. The most CO2 emissions were from China (28%), the United States (14%), the European Union (10%), and India (7%) – with China, the United States, and India all having increased emissions over the previous year. (The 28 member countries of the European Union showed a 1.8% decline in the years between 2012 and 2013.)

Although industrialized nations have traditionally produced the greatest percentage of excess greenhouse gases, developing nations will likely contribute more of these gases as they acquire more cars and other fossil fuel-burning technologies. Carbon dioxide is of primary concern, increasing by estimates of up to 30 percent since the beginning of the Industrial Revolution. But there are other greenhouse gases causing concern, including methane and nitrous oxides, which result from fertilizers used in agriculture, livestock farming, landfills, and energy production. Methane and nitrous oxide —while smaller in quantities than CO2—actually trap heat even more effectively than it does (methane over 20 times more and nitrous oxide almost 300 times more).

Some researchers have noted that the rise in greenhouse gases parallels rises in overall global temperatures, which have increased over the last century. According to the U.S. Environmental Protection Agency (EPA), average temperatures have risen across the contiguous 48 states since 1901, with an increased rate of warming over the past 30 years. Average global temperatures show a similar trend, and the top 10 warmest years on record worldwide have all occurred since 19982. Most scientists are convinced that the average temperature levels on Earth will rise by several degrees Celsius if greenhouse gases are not significantly reduced.

While these scientists agree that an increase in atmospheric CO2 and other greenhouse gas concentrations will raise average world temperatures, they do not agree on the effect of such global warming. Many researchers believe that global warming could disrupt weather patterns worldwide, causing coastal flooding, an increased range of disease-causing organisms, an altering of natural habitats, and the potential extinction of some plants and animals. Others believe that some of the changes could be beneficial—increasing food production, lengthening growing seasons for crops and decreasing the need for heating in many areas.

Some people believe either that global warming is not happening at all or that it could not be caused by human activities, pointing to natural warming and cooling trends that have occurred over the eons. Predicting future warming is difficult because the natural processes that contribute to climate are complex and have been difficult to simulate. However, recent advances in computer modeling technologies have strengthened the case for global warming.

Scientific Argumentation in the Classroom

Most people think of argumentation as a confrontation or quarrel. Scientific argumentation, however, is a process by which scientists and researchers present their ideas, results, and conclusions. Unlike a confrontation, scientific argumentation has the goal of refining and build consensus for scientific ideas—based on evidence—to come as close as possible to understanding the reality of the natural world.

In this process, scientists and researchers  use their data to make a claim supported with evidence. Other scientists can then critique the work, evaluating whether the claim is adequately supported, the evidence sufficient, the data appropriately analyzed, and the reasoning sound.

In scientific argumentation:

The claim is the conclusion made after analyzing the data or an answer to the question being tested. This should be no more than two sentences. The claim is a statement, not an explanation that delves into the reasons why it is so. The claim should sum up the conclusion of an investigation or answer a question. This is where less is more.

The evidence is the data collected that support the claim. The data should be appropriate for the problem and the amount provided should be sufficient to make the case. A quantitative summary of patterns and trends can be used if it clearly reflects the data, but data tables and graphs should not be included here.

Reasoning explains how the evidence supports the claim. What inferences can be made? This is where valid data examples are given to substantiate the claim. Data results should be quoted with explanations that tie them to the claim. This will be the longest part of the process and should include vocabulary terms and other information pertinent to the topic.

Discussion Questions

  1. In the past, what factors contributed to changes in Earth’s climate?
  2. What are the major sources of increased levels of carbon dioxide in the atmosphere since the mid-1800s?
  3. What is some of the evidence scientists have presented to support or refute the claim that Earth’s climate is changing due to more atmospheric carbon?

 

Climate Time Machine — Overview

By

In this project-based learning activity, students explore the geologic history of a particular region of the world to see how past climatic changes have altered the landscape. Students create museum exhibits to model what earlier climate patterns can reveal about current global temperature trends.

Note: We provide information and resource materials for the Great Lakes, which is a particularly interesting area to study on this topic. However, you may easily adapt the activity to focus on another region, state, or city. Have a look at local examples from New York and Kentucky.

Learner Objectives

  • Students will identify ways that climatic changes have altered the landscape of a specific region over time.
  • Students will determine how past climate patterns can inform our understanding of current global temperature trends.

Materials

Time Considerations

  • Getting Ready: 45 minutes or more
  • Doing the Activity: Five or more 50-minute periods
  • Evaluate: Varies, depending on option selected

Getting Ready

  • Make copies of the student pages.
  • Choose and plan for one or more of the engagement activities described in Step 1 of Doing the Activity.
  • Create a timeline for the project, including dates for specific components. A possible timeline might be:
    • Engage (introducing the project): one 50-minute class period
    • Explore (identifying what students need to know for the project): one 50-minute class period
    • Explain (planning and conducting research): one to two 50-minute class periods, plus time between for research
    • Elaborate (planning and creating exhibit): one or more 50-minute class periods
    • Evaluate (presenting exhibit): one or more 50-minute class periods
  • (Optional) Write the names of the project expert roles (Historical Geologist, Engineer, Climatologist, and Ecologist) on slips of paper and place into a bowl or hat.
  • (Optional) Arrange with an exhibit designer at a local museum to talk with your students about what goes into making a successful exhibit.
  • See Additional Resources to find other supports for teaching this activity.

PLT Conceptual Framework

  • 4.2. The structure and scale of ecosystems are influenced by environmental factors such as soil type, climate, availability of water, and human activities.
  • 5.0. Structures and systems may be stable and yet change over various periods of time.
  • 5.3. Ecosystems change over time through patterns of growth and succession. They are also affected by other phenomena such as disease, insects, fire, weather, climate, and human intervention.

Standards

See Standards Connections in the Appendices for a list of standards addressed in this activity.