Teaching Notes

Example Output

Stack with Color Example Output
Sample stack created with ImageJ.

Sea Ice Data from National Snow and Ice Data Center can be animated and analyzed with ImageJ.

Grade Level

This activity is designed to familiarize educators with techniques for accessing and analyzing sea ice data. It may also be used for students in grades 7-12.

Learning Goals

After completing this chapter, students will be able to:

  • measure the seasonal variations in sea ice extent;
  • discover long-term changes occurring in sea ice extent;
  • visualize the relationship between sea surface temperature and sea ice extent;
  • grasp the complex linkage between the sea-ice extent to the Arctic food web and human activities;
  • download tabular and image data related to sea ice extent and temperature;
  • manipulate image data with digital image processing tools;
  • animate a stack of images; and
  • plot tabular data as graphs and examine trends to make predictions.


Although the student chapter introduces what appears to be a limited question, "What has happened to the sea ice in your village in the Arctic?" this lesson can be expanded and customized in order to support many other science topics and curriculum standards. Some possibilities of further exploration and application are listed below.

  • Highlight the Human Impacts. Follow the link from the Arctic: A Friend Acting Strangely website to view an eyewitness documentary account describing how the retreat of the sea ice has caused impacts in Arctic villages and countries. Use this site to learn how people have responded to the changes in their environments. What are the challenges of climate change for humans in other environments such as, tropical islands, deserts? How should society respond to these dilemmas? Are we responsible for the fate of people in other countries? Are there positive economic outcomes of an ice-free Arctic?
  • Highlight the Biological Impacts: How has the changing ice edge affected the food web of the Arctic? How will this physical change affect animals, plants, humans?
  • Highlight the Physical Impacts: What role does the Arctic sea-ice play in the global climate patterns? Discuss albedo, changing salinity, ocean-ice-atmosphere connections.

Background Information

sea ice near the shore
Sea Ice along the shore near Baffin Island, August 2007, a record minimum year. Photo source: Betsy Youngman.

The area of ocean water covered by sea-ice in the Arctic has decreased dramatically since the 1960s. The September minimum has decreased over 8 percent per decade, or over 20 percent since the late 1970s. This decrease amounts to an area of the size of Alaska or twice the size of Texas. The thickness of the ice has also been reduced: estimates show that thickness has decreased between 20-40 percent or more. The Sea Ice Primer at the National Snow and Ice data center gives an excellent overview.

In September 2007, the sea ice reached a record low. To view the latest information visit the National Snow and Ice Data Center Pressroom.

The impacts of this decrease of Arctic sea-ice coverage are widespread and significant. These impacts include increased surface air temperatures, decreased salinity of ocean water, changes in habitat for marine mammals, and an increase in coastal erosion.

The thinner, less extensive sea ice makes the coastal areas more vulnerable to storm damage and coastal erosion. Therefore, some indigenous peoples in coastal villages are being forced to relocate to higher ground. In addition, native communities rely on the sea ice for hunting and transportation. The sea ice is an intimate part of their culture and changes in sea ice are already having an impact on their native way of life. Not only are villages at risk, so are major oil facilities. In Alaska, the villages of Shishmaref and Newtok are in the process of moving their villages to new locations. In Russia, an oil storage facility near the village of Varandei is also at risk. National Geographic's June 2007 Article, The Big Thaw, provide a graphic picture of the impacts on the Arctic region.

walrus on the beach
Walrus resting on shore. Walrus Island, August 2007. Photo source: Betsy Youngman.
Not only does the loss of sea ice affect the physical environment, it also impacts the biological world. Sea ice is a rich breeding ground for plankton and other small life forms that are the foundation of the entire food chain in the polar regions. Animals such as the polar bear, walrus and seal depend on sea ice to provide a platform from which to hunt and rest. These animals must now travel much greater distances across an open ocean before they find ice. The stress of this additional challenge to the animals of the Arctic has resulted in lower reproduction rate. Negative consequences extend beyond the immediate food chain to humans who depend upon the resources that these animals provide for their subsistence lifestyle. The loss of the sea ice jeopardizes the entire Arctic community, from the tiniest plankton to the greatest polar bear.

Additional comprehensive background information and images can be found in this NASA Earth Observatory ArticleSea Ice (2009).

Instructional Strategies

In order to catch the students' attention, begin the lesson with either a brief news article from a recent publication or a short video clip on the topic. Two resources for these are NSIDC News and the NOAA Arctic Change page. Other resources can be found in the Background Information and Going Further sections.

Once the students are engaged in the topic, and have reviewed sufficient background information, introduce the role-play scenario. Together, find Churchill on a map and discuss where it's located in the Arctic.

Initial Grouping: Whole Class
The lesson begins with the whole class and the initial case study dilemma focused on Churchill as an example village.

Subsequent Lessons: Small Group Expert Teams
After the students measure and plot the change in the sea ice in the Churchill region, small sub-groups can use the Internet and Arctic information to determine what this change might mean for another village. In order to accomplish this jigsaw, re-divide the students into small (3-6 person) expert teams to take on the roles of different people who are investigating and presenting the sea ice dilemmas from their own village's perspective. Each sub-group of students would then work with ImageJ and Excel to examine more local sea ice data. Suggested villages are drawn from the Arctic Climate Impact Assessment and listed in Part 5 of the lesson and Going Further.

Time Saving Suggestions:

  • Part 2 of the exercise, which is quite lengthy, can be split into two sections, animation and analysis.
  • If you need to shorten the length of time needed to complete this lesson, consider creating the two stacks of images in Part 1 ahead of time. Simply show the animations as a demonstration and ask students to make the sea ice measurements. Alternatively, animations of the changing sea ice are available at the National Snow and Ice Data center might be used as an introduction.
  • An even simpler lesson technique would be to have the students make the animations in ImageJ and do the measurements as a demonstration.
  • Another time saving technique is to download and locate the data sets on a central server or on each computer's hard drive before class begins.

Learning Contexts

This investigation can lead students in many directions. Although students begin the lesson by examining the impacts of receding sea ice extent, they will end up discussing a wide variety of subjects and questions that emerge as a result of global warming's impact on the Arctic.

The contexts or subject areas that this chapter is suited for are also broad. The chapter can take any one of three directions, human, biological, or physical. The outcome of the discussions will be guided by the parameters set by the individual instructor.

Science Standards

The following National Science Education Standards are supported by this chapter:

Grades 5-8

  • Use appropriate tools and techniques to gather, analyze, and interpret data.
  • Think critically and logically to make the relationships between evidence and explanations.
  • Communicate scientific procedures and explanations.
  • Technology used to gather data enhances accuracy and allows scientists to analyze and quantify results of investigations.8ASI2.4
  • Women and men of various social and ethnic backgrounds - and with diverse interests, talents, qualities, and motivations - engage in the activities of science, engineering, and related fields such as the health professions.

Grades 9-12

  • Formulate and revise scientific explanations and models using logic and evidence.
  • Use technology and mathematics to improve investigations and communications.
  • Scientists rely on technology to enhance the gathering and manipulation of data.

Time Required

Five to seven 45-minute periods will be needed to fully complete the case study and all exercises. Times will vary depending on prior knowledge and skills.

  • Case Study Introduction and Online Visualizations - 45 minutes
  • Part 1. Download and Install ImageJ and Sea Ice Data -30 minutes
  • Part 2. Import, Measure and Animate Sea Ice - 45 minutes
  • Part 3. Import and Process the Sea Ice Data in Excel - 40 minutes
  • Part 4. Download Data and Examine Arctic Temperature Trends - 40 minutes
  • *Part 5. Check the Trends Elsewhere in the Arctic - 40 minutes
  • *Optional. Assessment and Final Reports to class - 30 -45 minutes

*Note that while both Parts 5 and the Assesment are optional, they make the case study more complete. To save class time, students could complete these parts as homework, writing a paper instead of making an oral presentation.

Other Resources

Student Activity Sheet

A student activity sheet to accompany this lesson can be downloaded. To download either of these files, right-click (ctrl-click on a Mac) and select the "Download linked file" option.
A printer-ready version of the activity sheet (Acrobat (PDF) 81kB Feb24 08)
A modifiable version of the activity sheet (Microsoft Word 153kB Feb24 08)
An answer key to the student activity sheet (Acrobat (PDF) 214kB Feb24 08)