An article called “Measuring CO2 in the atmosphere” in the March 2010 issue of Chem 13 News describes how and where measurements of the atmospheric concentrations of CO2 are taken. Lew Brubacher, the author, explains that Mauna Loa is one of the locations where measurements are made because of its high altitude, 3,400 m, and its distance from any vegetation or industrial activity. This makes it a good site for monitoring background (or baseline) CO2 levels.
At the end of the article, Lew suggests the following:
Have your students do this as an exercise. Print out and enlarge Fig. 1 in reference 3 for them. Ask them to read the voltages for the three reference signals, fit them to a quadratic function using Solver in Excel and evaluate the air concentration from the signal they read for the air.
I took Lew’s suggestion and created the following student activity. Students are asked to first calculate a reference quadratic equation based on measurements with three known amounts of carbon dioxide.1 The data were taken from the voltage output from the Mauna Loa CO2 analyzer for November 17, 2006.2 The analyzer measures an hourly cycle of ambient air and three standard reference gases with known amounts of CO2. With this quadratic reference equation, students can calculate the range of the amount of CO2 from 2006 to 2009.
You may want to extend the activity and ask students for the up-to-date weekly average of CO2 (ppm) at Mauna Loa is.3