• What can ice core evidence from the past tell us about today’s climate?
• What role have humans played, if any, in causing the recent abnormally high CO2 levels?
• What impact will these heightened levels have globally and locally on Earth’s environments?

Segment 5
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Studying ice cores at the National Ice Core Lab, Alley shows how ancient ice contains records of Earth’s past climate. Over 400,000 years, and even longer, levels of carbon dioxide have risen and fallen from about 180 parts per million to 280, varying from colder in the Ice Ages to warmer in interglacial periods. Today, however, for the first time in more than 400,000 years, CO2 is at 390 parts per million and continuing to rise at 2 parts per million (ppm) per year. Alley relates the onset of this change to the Industrial Revolution.


The Annotated Script
Please refer to pages 48-54

• Students will understand that ice cores contain climate indicators such as carbon dioxide concentrations, from more than the past 400,00 years.
• Students will examine the historical relationship between temperature and CO2 levels.
• Students will understand that climate patterns cycle naturally, with historic data helping to define what has been the norm.
• Students will learn that current CO2 levels far exceed any in recorded human history.

Atom, carbon dioxide, climate, feedback, oxygen, parts per million (or "ppm")

One of the most exciting outcomes of ice core research is the robust, long term evidence from the past that's both contributing to our understanding of Earth's climate today and providing a foundation for future climate models. Using a guided inquiry approach is an effective way to launch the activities associated with "CO2 In the Ice Core Record."

You could start, perhaps, by asking "Where can you find carbon dioxide, CO2?" (It's all around us: we breath it out as we breath in oxygen. Another answer is in carbonated drinks: it's CO2 that makes them fizzy.) "How old is the CO2 in that can of soda?" (Not so old. CO2 is passed through water under high pressure during the manufacturing process.) "How old is the oldest CO2 and where could you find it?" (Ice core researchers have drilled down into deep ice which they know—from counting layers and other techniques—is some 800,000 years old. Bubbles in that ice function like tiny, frozen bottles, containing samples of Earth's ancient atmosphere, including CO2.)

Building on students' current ideas about climate change, pose several questions such as: "In what ways do scientists research Earth's climate patterns? How might they predict what will happen in the future?" Record student ideas, among which will hopefully be the hypothesis that "Data is gathered and analyzed" or "Researchers can look at what happened in the past."

Then show the video, and implement one or more of the following activities.

To test their ideas, in the following activities students will have a chance to investigate procedures and materials being used by ice core researchers today, and begin to draw conclusions about how scientists gain new knowledge by analyzing evidence.

The following activities are presented in a sequence that introduces students to concepts in order of increasing sophistication. They also represent a range of skills with the more elementary in the first, and high school and above in the last. Depending on time allowed and the age of your students, they can be introduced sequentially or individually.

1) CONCEPT: Snow builds up in layers and gets compressed into ice over long periods of time.


Students observe and measure model ice cores to simulate research by glaciologists. They will count the number of years of snow accumulation represented by their cores and graph data to discover trends of annual snowfall.

This activity provides a good elementary lesson on ice cores. It is listed for grades 3-6, however due to the concepts of scale and sequencing and the bar graphing skills required it may be more appropriate for grades 5-7, depending on your students' background. Materials are cheap and easily accessible, with the possible exception of a drill bit for wood. Allow for at-home prep time to prepare the cores. Evaluation suggestions are included.

Upper Elementary/Middle School Teachers:
Have students brainstorm what else might be discovered by examining the ice layers, then show the clip, CO2 in the Ice Core Record, as a culmination to your studies.

2) CONCEPT: Chemicals and particulate matter in the atmosphere get captured in the snow as it falls, with gases later trapped in bubbles inside the ice.


Students investigate the formation and physical properties of simulated ice cores. They graph "unseen" sulfur data from two ice core locations, draw conclusions about the impact of volcanic eruptions on weather at the time, and compare the discrepant 1816 event to long term climate patterns.

This hands-on activity offers a fun and easy way to demonstrate differences in annual ice core layers. Real world data is employed. Due to the graphing exercise, it is most appropriate for middle school and up. A bar graph could be constructed instead of the line graph suggested for younger students. Materials are cheap and easily sourced, extensions are offered and there is an evaluation page included.

Middle School Teachers:
Show the video clip CO2 in the Ice Core Record after Activity 2 or 1 and 2, as a specific example of ice core gas content. Note that one of the ice cores Richard looks at contains a very prominent ash layer resulting from the eruption of an Icelandic volcano some 50,000 years ago.

3) CONCEPT: Scientists use drills to extract the ice and analyze multiple climate indicators over time.


Students utilize an online tutorial to analyze "the most detailed record of Earth's climate for the last 110,000 years and some answers to the puzzle of how temperature, atmospheric gases, and other atmospheric particles interact to create climate." See Richard Alley's biography for his own role in the GISP2 project, and much more in his earlier book, The Two Mile Time Machine.

At upper elementary and middle school grade levels, introducing the video clip first could be used to excite interest in further knowledge. Access to a computer lab for multiple student use is required. The unit content can go beyond investigating CO2 to analyzing multiple data sets, and requires good graph analysis skills. This is recommended for high school teachers who want a quick introduction to ice core analysis with no hands-on preparation required. While no specific assessment tools are included there is a set of questions that could be used to evaluate student understanding.

4) CONCEPT: Changes in the levels of CO2 in the atmosphere are clearly visible from data collected and plotted over time. They vary seasonally, but the trend is upward.


High point: Allows students to work with real data through the simple graphing of original CO2 data at Mauna Loa, updated through 2009. This is also a good basic introduction to the "Keeling curve", see Annotated Script page 28.

Students work in groups, plotting carbon dioxide concentrations over time on overheads and estimating the rate of change over five years. Stacked together, the overheads for the whole class show an increase on carbon dioxide over five years and annual variation driven by photosynthesis. This exercise enables students to practice basic quantitative skills and understand how important sampling intervals can be when studying changes over time. A goal is to see how small sample size may give incomplete picture of data. This activity takes at least one class period. It requires an overhead projector and transparency sheets to project compiled data sheets.

Whether it's an elementary reflection that snowier climates produce thicker ice core layers, a middle school understanding that chemical and physical indications of past climates are recorded in ice sheets, or a high school level detailed analysis of various gas records from the past, at least one class period should be spent on thinking about the inquiry process and how various ice core research projects forward scientific knowledge in particular fields.

In-depth information about ice drilling projects, scientists and drills can be found at:

Grades 6-8
ESS Core Idea 4: Human activities are constrained by and, in turn, affect all other processes at Earth's surface
How do human activities alter Earth?
How do human activities alter Earth's climate?
How can humans reduce climate change and minimize its negative effects?

ET Core Idea 3: People are surrounded and supported by technological systems.
Effectively using and improving these systems is essential to long-term survival and prosperity

How do systems relate to larger and smaller systems?

Grades 9-12
ESS Core Idea 3:
Earth's surface continually changes from the cycling of water and rock driven by sunlight and gravity
How does climate change over space and time in response to both natural and man-made causes?

ET Core Idea 2:
Engineering design is a creative and interactive process for identifying
and solving problems in the face of various constraints

What are the different ways that problems can be researched?
What are some ways to find creative solutions?
What are the different factors that must be taken into account when solving technological problems?

Annotated Script
Learning Objectives
Teacher Tips
Suggested Actvities
Core Science Standards


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