Help, Our House is Sinking! Engineering Solutions for Thawing Permafrost

Objectives

The objectives of this lesson are:

• Students will know that climate change is happening most quickly in Arctic regions.
• Students will know that a warming climate is causing permafrost to thaw.
• Students will know that thawing permafrost is impacting infrastructure in Alaska, including roads and buildings.
• Students will design an engineering solution to create stable structures on top of thawing permafrost.
• Students will know that climate change is causing damage to structures and infrastructure, impacting communities.

Lesson Preparation

A suggested overarching phenomenon for this instructional segment:

• This lesson would be used as a culminating project for a unit exploring climate data. A suggested anchoring phenomenon for this learning unit is an image showing global temperature anomalies like the image shown below. Because this data is updated monthly, search for the most current image from NOAA. See the Resource section for a suggested link.

• Students should analyze the image to find temperature anomalies across the earth. The global temperature anomalies map will show blended land and sea surface temperature anomalies in degrees Celsius, based on average temperatures from 1981–2010. Keep in mind that, as of this writing, nine of the ten warmest recorded years have occurred since 2005. Those numbers are included in the baseline average temperatures. Note that the high latitudes have the largest temperature anomaly.

• Throughout the unit on climate change, students would gather evidence to explain how we know Earth’s temperatures are rising, why temperatures are rising, and evidence that this change is seen most directly at northern latitudes. In this final lesson, students will explore how rising temperatures are causing permafrost to thaw, and how this phenomenon is impacting infrastructure.

• The teacher will prepare two surfaces that will become test stations for students to use. One surface is frozen water. One surface is gelatin.

• Test surface one: At least one day prior to class, create the test surface that will represent frozen permafrost. For easier clean-up, place a plastic bag in the container to be used, add water to fill the container ¾ full, and freeze.

• Test surface two: At least one day prior to class, prepare a container that will represent thawing permafrost. Use gelatin such as Jell-O to create a semi-solid surface. To keep the test area clean and for easier clean-up, add the gelatin to a plastic bag and seal the bag. (In the examples below, plastic bags were not used.)

• Cover both surfaces with felt or cloth to represent soil.

• Gather materials to be used by students to build a structure. A variety of materials may be used, based on what items are readily available. The example uses Lego bricks for the building and rocks for added mass.

Procedure

DAY 1:

1. As a class, watch the video Losing Permafrost in Alaska https://ca.pbslearningmedia.org/resource/ean08.sci.ess.watcyc.bakedalaska/losing-permafrost-in-alaska/

Students may also read information about permafrost at https://www.alaskacenters.gov/explore/attractions/permafrost.

2. Discuss with students that permafrost is ground that remains frozen for at least two years. Because Arctic permafrost has been frozen for thousands of years, communities and infrastructure have been built on top of the permafrost, expecting the permafrost to remain intact.

As temperatures are rising, permafrost is thawing. Note: It is important to use the correct term, thaw, rather than melt. As a comparison, permafrost may be thought of as frozen meat. When the steak thaws, it still has density and structure. Ice will melt. When ice melts into water, density is lost. Saying that permafrost melts is not accurate.

3. Discuss what would happen to structures if the ground beneath them became soft. How could this affect buildings, roads, towers, and pipelines?

4. Ask students to design and build a structure such as a tower. The teacher should set criteria for height and mass for the finished tower, based on materials available and size of the testing area. For example, the teacher may require that all towers be at least 15 cm tall and weigh at least 100 grams.

Students may work in small groups for this activity. Each student should draw the structure and include measurements of height and width. List what materials were used to build the structure.

5. Test the structure’s stability by placing it on top of the frozen surface for 20 seconds. Add mass with rocks, small weights, or metal washers. The structure should remain upright. Record this result. Students may photograph or video their towers before and during the tests.

6. Students next place the structure, with added mass, on top of the gelatin surface, representing thawed permafrost, for 20 seconds. The structure is expected to tip.

7. Students brainstorm modifications to make to the structure so that it may stand upright on the thawed permafrost. Record ideas in the science notebook or lab sheet.

8. Modify the tower. Test on the thawed permafrost surface. Record results. Continue to modify and test, as time permits.

DAY 2:

Student teams take turns presenting their structure modifications and test results to the class. The class discusses general results. Apply the results to a larger setting. If the students’ community were built on top of permafrost that is thawing, what modifications would need to be made to stabilize structures?

If this lesson is used in a learning segment about the use of natural resources, students may discuss Trans-Alaska pipeline its use for delivery of crude oil from the Arctic to the continental United States. Students may find information about the Trans-Alaska pipeline at https://www.alaskacenters.gov/explore/attractions/trans-pipeline and https://www.alyeska-pipe.com/TAPS/PipelineFacts. Students should recognize that half of the 800-mile long pipeline is built over permafrost. Students can learn the engineering modifications made to the pipeline to protect the permafrost from thawing, but these modifications were made assuming that that permafrost, in general, would not thaw because of climate change.

Students can discuss the impacts of climate change on this delivery mechanism for crude oil, and our role in the use of fossil fuels.

Extension

For classrooms that are located in a cold climate, outdoor areas could be used for the activity. If you are in a climate where the ground freezes over winter months, consider installing a frost tube to monitor how deeply the soil in your area freezes in the winter months. Record these observations from year to year to monitor this local climate indicator.

A protocol for frost tube investigations may be found on the Global Learning and Observations to Benefit the Environment (GLOBE) website at https://www.globe.gov/documents/352961/353769/Frost+Tube+Protocol/5c9a552a-0677-48f0-ae4b-4cc0f8ba8f12

Lessons and information on constructing and installing a frost tube may be found here

Transferability

This lesson has been used with students in grades 4 - 6 with appropriate modifications. The activity was part of a multi-station polar science workshop for elementary students. For students in sixth grade, this lesson was part of a longer learning unit about the causes and impacts of climate change.

Resources

For background on thawing permafrost and other effects of climate change in Alaska, watch the short video Losing Permafrost in Alaska published by PBS Learning Media, California. https://ca.pbslearningmedia.org/resource/ean08.sci.ess.watcyc.bakedalaska/losing-permafrost-in-alaska/ The video may be downloaded to a computer for viewing without needing internet access.

The Alaska Climate Research Center website page showing the departure of temperature and precipitation from 1981 – 2010 normal readings. Use the calendar dropdown choices to select current and past data. See http://akclimate.org/departure-maps

To find map images of ocean and land temperature anomalies, go to NOAA National Centers for Environmental Information website. Data is updated monthly. See “Global Climate Report” at https://www.ncdc.noaa.gov/sotc/global/201905. Alternately, use the key words “global temperature anomaly” to find this resource. Check both the document and image pages suggested for this web search.

For background information about permafrost, go to https://www.alaskacenters.gov/explore/attractions/permafrost by Alaska Public Land Information Centers.

For background information on the Trans-Alaska pipeline that is written for a general audience, see The Trans-Alaska Pipeline at https://www.alaskacenters.gov/explore/attractions/trans-pipeline. The website is published by the Alaska Public Land Information Centers.

For a fact sheet about the Trans-Alaska pipeline, go to https://www.alyeska-pipe.com/TAPS/PipelineFacts. The website is published by the Alyeska Pipeline Service Company. Copyright 2011.

Assessment

See Project Rubric.

Author/Credits

Regina Brinker, PolarTREC Teacher 2014
Livermore Valley Joint Unified School District
Livermore, CA
brinker.science [at] gmail.com