Unit 2: Temperature--A Global Trendsetter
How have average global air temperature and sea level changed in the last three decades? Have the changes been consistent? Can future changes in air temperature and sea level be predicted? In this unit, students will become familiar with the concept of a time series by calculating recent air temperature and sea level trends and projecting these measurements for 2100. They will also begin to consider environmental factors in addition to temperature that could influence sea level and the potential implications of sea level changes during the next century.
Unit 2 Learning Outcomes
- Students will calculate the global sea level trend over various time scales including projections for global sea level by 2100.
- Students will identify at least three factors that influence sea level changes, rank each factor's respective contribution to sea level change, and compare their rankings with Intergovernmental Panel on Climate Change (IPCC) measurements.
Unit 2 Teaching Objectives
- Cognitive: Facilitate consideration of the air temperature's influence on the atmosphere, ocean, and cryosphere, and the consequences of atmospheric warming on sea level.
- Behavioral: Provide an opportunity for skills development in calculating rates of change and predicting changes in a natural system.
- Affective: Encourage reflection about the role of uncertainty in scientists' understanding of a complex system.
Context for Use
The content in Unit 2 is appropriate for introductory geology, oceanography, meteorology, and other geoscience courses; sophomore-level courses in which geodesy and/or climate studies are being introduced; or non-geoscience courses where climate studies and/or the nature and methods of science are being investigated. Unit 2 activities can easily be adapted to serve small- or large-enrollment classes and can be executed in lecture and lab settings as an interactive lecture activity, an in-class activity in which students work in small groups, a short lab exercise, or as part of a ~two-week investigation of the use of geodesy to understand cryosphere and sea level changes using the entire Ice Mass and Sea Level Change module. This is the first unit in the Ice Mass and Sea Level Change module that deals heavily with data and precedes Unit 3: Warm with a chance of melting on spatial and temporal changes in Greenland ice mass using snowmelt, ice velocity, ice elevation, and temperature data from four study sites on the Greenland Ice Sheet. If the entire two-week module will not be utilized, we recommend pairing Unit 2 with Unit 3: Warm with a chance of melting to expose students to a variety of spatial data and to give students an opportunity to make qualitative predictions about changes in ice mass in addition to the quantitative predictions they made in Unit 2. Alternatively, Unit 2 could be paired with Unit 5: Regional sea level changes—a tale of two cities to consider potential societal impacts of the sea level changes that they projected for 2100 in Unit 2.
Description and Teaching Materials
Part 1:Sea Level Rise slides - Unit 2 Part 1 (PowerPoint 2.2MB Nov12 15)
In small groups (could be done as a think-pair-share) or as a whole group, students will generate a list of as many environmental factors as possible in addition to atmospheric warming (these factors could be a consequence of atmospheric warming, however) that could result in sea level changes. Students will not be instructed to think specifically about local vs. global sea level changes, so we anticipate that some responses will be specific to local sea level changes and others will be global. In small groups or as a whole-group discussion, students will rank each environmental factor according to its relative influence on sea level. This presentation can be used to guide the discussion.
Part 2:Helpful Math slides - Unit 2 Part 2 (PowerPoint 1.9MB May21 21)
This activity will walk students through rate calculations and plotting of trend lines. If students need additional preparatory exercises, some are available on The Math You Need When You Need It tutorial on rates of change. The attached presentation Helpful Math slides - Unit 2 Part 2 (PowerPoint 1.9MB May21 21) can be used to walk students through definitions of rates, trend lines and anomalies. In Part 3, students will look at temperature and sea level rise data and calculate rates of change and draw trend lines.
In class, students will be provided with an air temperature time series from 1992-present and sea level data for the same time period. (Depending on class size, time constraints, and whether Unit 2 is being used in a lecture or lab setting, the instructor may choose to provide students with a time series or have students create their own time series by hand or using Excel from data in ASCII format.) Students will calculate temperature and sea level trends and use their calculations to project temperature and sea level data points for the year 2100.
- Unit 2: activity (student) (Microsoft Word 2007 (.docx) 1MB May21 21)
Unit 2: activity (student) PDF (Acrobat (PDF) 1MB May21 21)
- Unit 2: activity (figures) (PowerPoint 2007 (.pptx) 1.6MB May21 21)
Raw data (if instructors want students to create the plots themselves). Guides for teaching with Excel are available. (Resources Graphing Tutorial: Graphing with Excel has a section on plotting trend lines that might be useful.)
- Air temperature annual anomaly data (1880-2020) (Text File 4kB May21 21)
- Air temperature monthly anomaly data (1992 - 2021) (Text File 7kB May21 21)
- Sea level data (1992-2020) (Text File 19kB May21 21)
Instructors may want to spend some time describing the Intergovernmental Panel on Climate Change (IPCC) climate models and projections. This can be done as a short gallery walk or in-class discussion using the attached presentation IPCC climate models - Unit 2 Part 4 (PowerPoint 15.8MB Nov12 15).
Teaching Notes and Tips
Depending on the components of Unit 2 that are implemented in class, the duration of brainstorming, and the teaching techniques employed (i.e., gallery walk vs. small group work vs. lecture vs. discussion), Unit 2 could consume 1-2 hours of class time. To prepare for Unit 2, instructors may choose to assign a preparation exercise on drawing trend lines and calculating rates of change. The activity worksheet (part 3) should be copied before class (each student should receive a copy, although they may work together to complete it), PowerPoint presentations should be downloaded, and instructors should have a copy of the answer key. Instructors implementing Unit 2 in a computer lab should download the raw data for constructing the time series prior to the class meeting. We recommend explicit discussion of the concept of anomalies before students begin the calculations. When students are considering the relationship between air temperature and sea level, we found that unless prompted to determine a mathematical relationship, many students simply stated that as air temperature increases, so does sea level. For additional teaching tips and descriptions of classroom implementation strategies, refer to the Instructor Stories page.
Example #1: After students have made their 2100 sea level prediction, instructors can poll the class (either informally or using a concept test for large-enrollment classes) to verify that student rate of change calculations match sea level calculations. Instructors can also assess during class whether student sea level and temperature projections fall within IPCC projections.
Example concept test format (this could be projected on a PowerPoint slide and answered using clickers, cell phones, or "close your eyes and raise your hand"):
Based on your calculations, which of the following is the best sea level prediction for the year 2100? (Provide four choices.)
Example #2: There are several informal and formal methods that instructors can use to assess the gallery walk available on the SERC website. The goal of this gallery walk is for students to compare their temperature/sea level predictions and their ideas about environmental contributors to sea level changes to published data.
Summative assessment questions:
Level 1 example: (use the air temperature time series provided)
Calculate the average rate of change in air temperature from 2000 to 2020.
(Could also be done as a multiple-choice question, e.g., "What is the average rate of change in air temperature from 2000 to 2020?" with four choices.)
Level 2 example: (figure similar to NASA Global Temperature Trends provided)
You have been provided with data comparing global air temperatures between 1880 and 2010 to the average air temperature from 1961 to 1990. For example, a value of "0" for a particular year means that the air temperature was the same as the average air temperature from 1961 to 1990.
(A) How has air temperature risen or fallen from 1980 to 2010? By how much has global air temperature changed from 1980 to 2010? Please express your answer in degrees C.
(B) Name and describe two ways that this observed temperature trend could lead to changes in sea level. You may include labeled diagrams to support your answer, but you must include a written explanation.
Scoring: scoring rubric below assuming that this is a 6-point question. Example Unit 2 Assessment Rubric (Microsoft Word 2007 (.docx) 98kB Sep23 15)
References and Resources
- Report: In the IPCC AR5 report, Chapter 13 describes sea level observations, predictions and models.
- Data: Air temperature time series data and additional graphs are available from NASA.
- Data & Information: University of Colorado Sea Level Research Group