Human Energy Systems | Activity 2.4

Use the slides to have a discussion about the four phenomena and also the four considerations for each.

Show slide 3 of the PPT. Divide students into their home groups from the previous activity. Have them look at their completed versions of 2.1 Finding Patterns Tool for Earth Systems. Ask volunteers to explain the representation for each of the large-scale data sets. During the discussion, listen for their ideas. The class should come to consensus about the ideas for each graph and have a working definition of “representation” at this point. Listen to see if they can identify…

• Keeling Curve (Atmospheric CO₂): CO₂ levels at Mauna Loa are represented. The red line represents daily/monthly (short term data) and the black line represents monthly averages. The time period is 1960-2015.
• Sea Level: Change in sea level in mm is represented on the graph. The black line represents the global change from the average for that time period. The graph shows data from 1993-2017.
• Global Temperature: Change in global temperature is represented on the graph in degrees Celsius from 1880-2010. Dots above the 0 indicate global temperatures higher than average for that time period. The black dots represent each year’s average, and the red line shows a 5-year running mean.
• Two-year Atmospheric CO₂
  : Variables are time and atmospheric CO₂ concentrations. Time period is April 2013-March 2015.

Use slide 4 of the PPT to discuss generalizability with the students. During the discussion, listen for their ideas. The class should come to consensus about the ideas for each graph and have a working definition of “generalizability” at this point.

• Keeling Curve (Atmospheric CO₂): These data are generalizable to the Northern hemisphere only (in the Southern hemisphere the short-term variability is the opposite, although there is a similar overall trend of increase).
• Sea Level: These data represent global averages, so they are not generalizable to local regions, which will vary.
• Global Temperature: These data represent global averages, so they are not generalizable to local regions, which will vary.
• Two-year Atmospheric CO₂
  : This represents atmospheric CO₂ concentration at Mauna Loa in Hawaii. Other locations in the Northern Hemisphere show similar patterns (but not exactly the same).

Use slide 5 of the PPT to discuss short-term variability in Arctic sea ice with the students. Note that changes from one year to the next are random and unpredictable.

Use slide 6 to discuss short-term variability for the other phenomena. During the discussion, listen for their ideas. The class should come to consensus about the ideas for each graph and have a working definition of “short-term variability” at this point.

• Keeling Curve (Atmospheric CO₂): Short-term variability (during one year) shows a predictable pattern: CO₂ levels go up each winter and down each summer.
• Sea Level: Short term variability (from year to year) fluctuates in an unpredictable way. There is no clear pattern in the short-term.
• Global Temperature: Short term variability (from year to year) fluctuates in an unpredictable way. There is no clear pattern in the short-term.
• Two-year Atmospheric CO₂
  : Short term variability (from day to day) fluctuates in an unpredictable way. But there is a clear pattern in variability from month to month.

Help students notice that short-term variation follows a predictable pattern for atmospheric CO2 but not for sea level, global temperature, or Arctic sea ice.

Use slides 7-8 of the PPT to discuss long-term trends with the students. During the discussion, listen for their ideas. The class should come to consensus about the ideas for each graph, and have a working definition of “long-term trend” at this point.

• Keeling Curve (Atmospheric CO₂): The long-term trend (black line of yearly averages) shows a positive trend.
• Sea Level: The long-term trend (there is no trend line on the graph) shows a positive trend.
• Global Temperature: The long-term trend (red line of running means) shows a positive trend.
• Arctic Sea Ice: The long-term trend (blue line) shows a negative trend.

Use slide 9 to help students identify that three of the phenomena have a positive trend (CO_2, sea level, and global temperatures) and one has a negative trend (arctic sea ice).

Tell students that now they have identified these patterns in large-scale data sets, but they don’t have evidence yet for WHY these trends are happening! Ask students if they have any ideas at this point, or if they have any questions.

Have students complete the far-right column in their 2.1 Finding Patterns Tool for Earth Systems. They can complete these individually or as a group.

• Use slide 9 to record their ideas before moving on to the next lesson.
• Tell students that they will return to these questions later in the unit.
• Remind students that they do not yet have evidence to explain how these patterns are related or what causes them, but that this is what the remainder of the unit will help them figure out.

Show Slide 10 of the 2.4 Evidence-Based Arguments for Patterns in Earth Systems PPT.

• Pass out a Learning Tracking Tool for Human Energy Systems to each student.
• Explain that students will add to the tool after activities to keep track of what they have figured out that will help them to answer the unit driving question.
• Discuss goals for this lesson.
• Have students write the activity name in the first column, "Questions for this Lesson."
• Have a class discussion about what students figured out during the activity that will help them in answering the lesson driving questions:
• What causes the annual cycle: CO₂ concentrations in Hawaii to go down every summer and up every winter?
• What causes the long-term trend: CO₂ concentrations to go up every year?
• How can we predict what will happen to CO₂ concentrations in the future?
• When you come to consensus as a class, have students record the answer in the second column of the tool.
• Have a class discussion about what students are wondering now that will help them move towards answering the unit driving question. Have students record the questions in the third column of the tool.
• Have students keep their Learning Tracking Tool for future activities.
• Example Learning Tracking Tool