Lab Exercise: Greenhouse Gases: We’ve Got Effects, Live Effects
In this lab, students learn how greenhouse gas concentrations affect our atmosphere and why this is important. Students investigate greenhouse gas concentrations, global warming potentials, and lifetimes of various greenhouse gases. The lab contains a hands-on component where students explore how CO2 “traps” heat, thus operating like a greenhouse. After the lab, students will apply their knowledge to a New York City case study on climate change.
Students will learn the following: • To determine greenhouse gas concentrations • To analyze global warming potentials • To extrapolate CO2 projections for the next 100 years • To understand precisely how the greenhouse effect operates
CONTEXT FOR USE
The format suggested for this lesson is a lab. The class size can vary from twenty-five to forty students depending upon the size of the room. Laptops for groups or individual PCs are necessary for viewing online data sources. The greenhouse effect lab requires minimal equipment and space; therefore its best not to have fixed desks, but rather a large seminar style room or a laboratory. Multimedia capability is necessary - a large screen and LCD projector. The lab component requires an estimated ninety minutes (forty-five minutes per section - section one: data; section two: hands-on greenhouse effect). Some understanding of climate change and sources of greenhouse gases would be helpful. Referencing a lecture(s) prior to the lab (or access to lecture notes for reference) would provide ample support to complete the lab effectively (see links to lecture notes below).
ACTIVITY DESCRIPTION AND TEACHING MATERIALS
The structure and primary components of this lab lesson is sourced from Columbia University’s Earth Environmental Systems Climate (EESC) course. The hands-on lab comes from a Northwestern University global warming project.
In the data portion of the lab, students review a greenhouse gas data table that shows the concentrations, global warming potentials, and lifetimes for a variety of greenhouse gases (GHGs). There are three associated tasks. Task one has students ranking GHGs in terms of abundance and atmospheric lifetime. Task two has students scrutinize projections of CO2 for the next century. If students completed the CO2 concentration lab prior, they will compare this projection to the one they made of the Mauna Loa trend(s). In the final data task, students review a current greenhouse gas chart and investigate the growth rate of HFC-23 (which replaced CFCs), but it is itself a greenhouse gas.
After the examination of GHGs in the atmosphere, students shift gears to explore how CO2 prompts the greenhouse effect. The lab poses the question: Does carbon dioxide trap heat more effectively than normal air? Students create a hypothesis in response to the problem.
Follow preparation and set-up procedures. Students need to wear goggles and closed toe shoes. All materials are easy to obtain and use. Electricity is required for the actual procedure. Depending on the size of the class and available facilities, this procedure could be conducted in small groups or in a single demonstration. See the link for complete preparation instructions (below).
Once the experiment is prepared, both flasks are placed in front of a lamp containing a 150-watt light bulb. The lamp should not be turned on until students are ready to take measurements. It’s important that flasks share the lamp equally. Remove the Parafilm from the CO2 sample. Insert thermometers or temperature probes into each flask. Take the first temperature reading. Now turn on lamp. Record temperature for each flask every 30 seconds until they level off. After temperatures level off, remove the thermometers. Light two matches and drop in each flask; observe results.
Below are the links for source material and resources:
· EESC course page:https://courseworks.columbia.edu/cms/
· Northwestern University Global Warming Project: www.letus.northwestern.edu/projects/gw/pdf/C09.pdf
· New York City Greenhouse Gas Inventory: www.nyc.gov/html/om/pdf/ccp_report041007.pdf
After the experiment, students will take part in a closing discussion, addressing the following questions:
- Why are scientists so concerned about CO2 when its GWP is lower than other GHGs? How does the greenhouse gas effect experiment support or refute this claim?
- Why do CO2 concentrations increase for all scenarios? What is the primary difference between CO2 and CH4 that explains this behavior?
- In the experiment, which flask represented the experimental group? The control group? What was the dependent variable?
- In this experiment, what did the lamp represent? What did the flaks represent?
- Was there a difference in the behavior of the lit matches when they were dropped into the flask?
- What can we take away from our analysis of CO2 concentrations and model of the greenhouse gas effect? Do higher concentrations of CO2 in the atmosphere plausibly lead to increases in temperature?
· Computer lab or moveable laptops with Internet access and Excel.
· LCD projector
· Handouts - lab instructions
· “Writing a Lab Report” (may have already been disseminated)
Greenhouse Effect Lab
· Lab instructions
· Safety goggles
· 2 1000ml flasks
· 1 250ml flask
· 1 Shallow pan
· 1 Stopper apparatus (#6 stopper, 6cm glass tube, 30cm of flexible tubing)
· 4 Effervescent tablets
· 2 Lab thermometers or probes
· 1 Lamp with 150watt bulb
· 1 Ring stand
Greenhouse gas lab
Instructors/TAs may find it useful to refer to lecture notes from the following two lectures: • Climate Change: Past, Present, Future II (CO2) • Greenhouse Gases The notes lead up to the lab and thus will aid in the facilitation of a more clear and concise dialogue regarding CO2 concentrations and greenhouse gases.
Students summarize their findings in a lab report. The Greenhouse Effect lab can operate as a two-part lab - if the greenhouse lab is used in conjunction with the CO2 concentration lab, students will complete the second section after the hands-on portion of the greenhouse lab. In the hands-on section, students incorporate procedures, being sure to cite the data used and the variables examined. Students should restate their hypothesis and use data to support or reject. Additionally, students will add onto their New York Case Study. Review the study, paying particular attention to the data tables associated with the various point sources for CO2 and other greenhouse gases in New York City. Answer the following questions: 1. What activities and industries are contributing the most to CO2 concentrations in the atmosphere? 2. What can be done to curb the emission of greenhouse gases in New York City?
REFERENCES AND RESOURCES
Below are the links for source material and resources: • EESC course page: https://courseworks.columbia.edu/cms/ • Northwestern University Global Warming Project: www.letus.northwestern.edu/projects/gw/pdf/C09.pdf • New York City Greenhouse Gas Inventory: www.nyc.gov/html/om/pdf/ccp_report041007.pdf
Learn what a greenhouse gas is, why their concentrations are important, and how the greenhouse gas effect operates.