Comparing Trends in Global Temperature to Global CO₂ Levels

Rob Rouse

Talent Unlimited High School, Manhattan

Summer Research Program for Science Teachers

August 2008

Unit: Atmospheric science and/or global climate change

Topics: Data collection regarding CO₂ levels in the atmosphere. Global average temperature changes over time. Possible links between global temperature increase and global CO₂ increase.

Aim: How do trends in global CO2 levels compare to trends in global temperature changes?

Do Now: Answer the following questions in complete sentences by rephrasing the question as a statement. Use pictures for drawing questions. If it isn’t a question, just do what it says!

1) What are the two fates of solar radiation that is headed toward the earth? In other words, what can happen to solar radiation headed toward the earth?

2) What are the four most common greenhouse gases in the atmosphere?

3) What is the result of having greenhouse gases in the atmosphere?

Materials: The worksheet on the following page.

The source of the data in the figure at the top on the first page of the worksheet is from the Mauna Loa observatory. The observatory has been recording atmospheric CO₂ data accurately since 1969. Students should know that the data collected at Mauna Loa is not open to debate—meaning it can be taken as fact.

The source of the data in the figure at the bottom of the first page of the worksheet is the NASA Goddard Institute for Space Studies and is equally reliable.

Rob Rouse prepared the questions on the reverse. Feel free to use them or change them.

Trends in CO₂ Levels                       Date________               Name_______________       

Directions: The following CO₂ level data shows average measurements taken at the Mauna Loa Observatory in Hawaii. Use these data to answer the questions on the front of the handout.

                                                            CO₂ in the Atmosphere

Trends in CO₂ Levels                       Date_____           Name____________________

1) Graph the data from the chart on the other side. Prepare the x axis to include the years 1970 to 2050, and the y axis to represent CO₂ levels from 325 ppm to 425 ppm. Plot the data and draw a curve to connect the points. The origin should be year 1970, concentration 325. Every line on the x-axis should represent 2 years and every line on the y-axis should represent 5ppm.

2) Assuming the trend in your curve will continue, extrapolate (draw in a line predicting the continuing trend) from your graph with a dashed line from the last year for which you have data to the year 2050.

3) Make the following predictions based on your graph:

a.       What does your graph indicate about the general change in CO₂ levels since 1970?

b.      Based on your extrapolation, predict CO₂ levels for the next year, the year 2020, and the year 2050.

Next year:                                           2020:                                       2050:

            c.       Compared your graph to the average global temperature graph and interpret your results in terms of what you believe the relationship between CO₂ and temperature is.  

Procedure of Lesson: The students should have some atmospheric science background. This lesson works well as a reinforcing activity or as an introduction to global warming activity that shows students that increased CO₂ levels are CORRELATED with increased temperatures (notice that correlation does not imply causation).

Summary: Discuss the results that the students find after graphing the data. The extrapolated line is especially interesting to discuss since it proceeds clear off the graph.

Homework: Possible assignments include collecting other atmospheric information from reliable climate change websites such as the Mauna Loa observatory site or the NASA GISS site.

National Standards:

Content Standard A:

As a result of activities in grades 9-12, all students should develop

1) Understandings about scientific inquiry

Teaching Standard D: 

1) Make the available science tools, materials, media, and technological resources accessible to students

Teaching Standard B:

1) [focus] the attention of students on how they know what they know and how their knowledge connects to larger ideas… promote many different forms of communication (for example, spoken, written, pictorial, graphic, mathematical, and electronic)