Unit 5: Modern CO2 Accumulation
Students will examine data that record the modern increase in carbon dioxide concentrations and the associated increase in average temperatures, and they will investigate the effects of carbon dioxide on various components of the Earth system (atmosphere, cryosphere, hydrosphere — oceans). Students also learn how the burning of fossil fuels contributes to increases in atmospheric carbon dioxide.
This unit addresses several of the grand challenges facing society, including energy and its relationship to the environmental issues of climate change and environmental degradation.
- Students will relate seasonal and long-term trends in atmospheric concentrations of CO2 to fluxes in the carbon cycle.
- Students will articulate the modern consequences of increasing CO2 levels, including climate change and ocean acidification.
- Students will make predictions about future trends in atmospheric CO2 concentrations and their consequences.
Context for Use
This unit is designed for use in an introductory-level college geoscience or environmental science course. It can be adapted for use in online instruction, individual/independent study courses, and large lecture hall-style classes. The exercises are designed to be completed in a 50-minute course structure, but they can be shortened or lengthened based on the level of detail desired for class discussions. This time estimate does not include any out-of-class extensions to the activities. Students and instructors will need copies of handouts, computer, access to the Internet, and a classroom projector.
Description and Teaching Materials
Description and Teaching Materials
The overall flow of this unit is as follows:
This unit begins with two short videos. The videos may be shown in class, or assigned for students to view before coming to class.
- Students watch a short video about Charles David Keeling and the development of the record of carbon dioxide in Earth's atmosphere.
- Students watch a video showing the buildup of carbon dioxide in Earth's atmosphere.
Students explore changes in carbon dioxide over various intervals of time in a Gallery Walk activity.
Following the Gallery Walk, the instructor shows the graphs as part of a PowerPoint presentation, and asks the groups to report orally on their thoughts about each graph. The instructor will provide feedback, clear up misconceptions, and offer additional information.
After the PowerPoint presentation, students watch two short videos on ocean acidification.
A suite of optional activities are also included, which can be used for homework, labs, or longer classes.
The instructor prints out a series of diagrams and questions. The diagrams and questions can be taped to the wall in the classroom, on tables in the classroom, or in the hall, along with a piece of chart paper for each diagram. Markers will need to be provided for students to write on the chart paper.
Students watch two short videos about carbon dioxide in class, or this can be assigned for students to do before class.
Video 1. Charles Keeling (1928-2005) and NOAA's Mauna Loa Observatory from NOAA ESRL (3:49 minutes)
Video about Charles David Keeling and the development of the record of carbon dioxide in Earth's atmosphere.
Video 2. A year in the life of Earth's carbon dioxide from NASA Goddard (3:10 minutes)
A NASA visualization showing plumes of CO2 in the northern hemisphere, and seasonal cycles of CO2.
Gallery Walk (20 min, allowing 2 minutes per diagram)
The instructor prints out a series of ten diagrams. The diagrams can be taped to the wall of the classroom, in the hall, or on tables in the classroom. Questions are provided for each diagram. Students circulate around to see each of the diagrams, consider and discuss the questions provided, write answers on the chart paper, and reflect on the answers written by other groups. Students are asked to speculate on causes of the changes in CO2. The annual cyclicity is due to seasonal changes in vegetation, and seasonal changes in fossil fuel use (keeping in mind that most landmasses are located in the northern hemisphere). Students compare highs and lows of CO2 levels over a two-year period and see that the peaks and valleys are a little higher each year. Students are asked to predict what CO2 levels were like previously, and to predict what CO2 levels will be like in future years. Students examine CO2 data from ice core back to 1700 to determine when CO2 began to rise rapidly, and to interpret the reason why. Ice core data also show the cyclicity in CO2 levels over the past 800,000 years. The presentation shows the relationship between CO2, global warming, and ocean acidification.
Unit 5 Gallery Walk Activity - Diagrams and Questions (Microsoft Word 2007 (.docx) 1.5MB Aug17 16)
Unit 5 Gallery Walk Activity - Diagrams and Questions - PDF version (Acrobat (PDF) 1.6MB Aug17 16)
For comparison, Keeling curves, updated weekly, can be viewed on the Keeling Curve site from Scripps Institution of Oceanography. Keeling curves are available for several time intervals (one week, one month, six months, one year, two years, or the full record going back to 1958).
Unit 5 PowerPoint Presentation (20 min)
Following the Gallery Walk, the instructor shows the PowerPoint Presentation with the questions for each diagram, gathers student feedback on the questions, and makes sure that critical concepts are covered that the students may have missed. Computer, Internet access, and a classroom projector are needed. It will be helpful to have a marker or chalk to write student responses on the board. At the end of the presentation there are review questions that students can answer orally or in writing.
Unit 5 PowerPoint (PowerPoint 3.4MB Aug17 16)
Following the PowerPoint presentation, students watch two videos on the consequences of ocean acidification. These videos are embedded in the Ocean Portal website from the Smithsonian National Museum of Natural History. It will be helpful for the instructor to make sure that the videos will run on the in-class computers if the videos will be shown during class time.
Video 3. Ocean Acidification by the Alliance for Climate Education (3:01 minutes)
This animated short video provides an excellent, easy-to-understand overview of CO2, and how it causes ocean acidification. The video discusses the effects of ocean acidification on sea creatures, the marine food chain, and human impacts.
Video 4. Oyster Farmers Facing Climate Change, a Vimeo video from Benjamin Drummond and Sara Steele (4:36 minutes)
This video shows the effect of ocean acidification on the biosphere, as oyster farmers tell of the effects of changing ocean chemistry on oysters.
Following the videos, students can answer the Review Questions at the end of the PowerPoint, either individually or in small-group discussion.
Optional Activities and/or Homework.
1. U.S. Environmental Protection Agency Household Carbon Footprint Calculator (20 min)
Students use the U.S. Environmental Protection Agency Household Carbon Footprint Calculator (or direct link to footprint calculator) to estimate their annual carbon dioxide emissions.
Online activity - How much carbon dioxide do you generate? Student Worksheet (Microsoft Word 37kB Aug17 16)
Online activity - How much carbon dioxide do you generate? Student Worksheet (Acrobat (PDF) 81kB Aug17 16)
Online activity - How much carbon dioxide do you generate? Instructor’s Guide -- private instructor-only file
2. Graphing authentic data on CO2 changes, 1958–present (15 min)
Using authentic CO2 data from Mauna Loa Observatory in Hawaii, students produce graphs of the Keeling Curve using Excel. This activity requires access to a computer with Excel spreadsheet program. Mauna Loa Observatory CO2 data are available from NOAA's Global Greenhouse Gas Reference Network. Click on the Data tab, and on the Data page, look for:
Mauna Loa CO2 monthly mean data
Mauna Loa CO2 annual mean data
A. Convert the annual data to a graph
Copy the data into an Excel file and produce a scatter plot graph. You will need to click on the "Data" tab, and look for the "Text to columns" data tool. This tool will separate the data from the web page into individual columns. You will only need two of the data columns — year and CO2 concentration.
Select the year and mean columns. Make a "scatter plot" of the data in these two columns (year and mean or average CO2 concentration). (Click on "Insert" tab, and look for Scatter graph with lines.) Year should be on the X-axis, and CO2 should be on the Y-axis. Label the Y-axis for "Carbon dioxide (ppm)", and scale the axis from a minimum of 250 to a maximum of 450. Label the X-axis as "Year".
Right click on the data points and click on "Format Data Series". Using "Marker options" and "Marker fill", change the data markers to the smallest possible black dots (size 2). Right click on the data points and click on "Format Data Series". Use "Line color" to make a thin red line. Stretch your graph as necessary so that you can see the individual data points, connected by the red line.
B. Convert the monthly data to a graph
Repeat the basic procedure outlined in Part A, above, for the monthly CO2 data (Data from March 1958 through April 1974), following the additional instructions below.
Copy the data into Sheet 2 tab in Excel. Use the "Text to columns" data tool. Put all column heading labels into one row at the top. Where data are missing, it appears as -99.99. Delete these values and leave those cells blank, or you will end up with a very odd graph.
Select the decimal date column, and the average column. Make a "scatter plot" of the data in these two columns. Label the axes and make the markers and line as you did in Part A. Set marker options to NONE. Use "Line color" to make a thin red line. Stretch your graph as necessary so that you can see the individual data points, connected by the red line.
Teaching Notes and Tips
Several optional activities are provided for homework or for labs and longer classes. In the first activity, students use the U. S. Environmental Protection Agency Greenhouse Gas Emissions Calculator to estimate their annual greenhouse gas emissions. This may be done in class or as a homework assignment. If it is done in class, the instructor will want to have a heating bill available to provide sample data for students to use.
The students can follow the directions in the second optional activity to use Excel to draw the Keeling Curve from authentic CO2 data from Mauna Loa Observatory, if computers are available.
Links to additional videos are provided in the References and Resources section below.
Unit 5 Formative Assessment:
The activities in this unit can be used formatively, so students can develop their understanding, ask questions, and learn by trial in class with their peers. There are several formative assessments in this unit that are ungraded (theGallery Walk, questions in the PowerPoint presentations, and review questions at the end of the PowerPoint). There are also optional activities which can be either graded or ungraded, at the instructor's option (U. S. Environmental Protection Agency Household Carbon Footprint Calculatorand Graphing authentic data on CO2 changes).
Unit 5 Summative Assessment:
There is a 15–question summative assessment for Unit 5 with a selection of multiple choice and short answer questions.
References and Resources
- The Cost of Carbon YouTube video by the Climate Reality Project (3:26 minutes).
- NASA video, A Year in the Life of Earth's CO2 (3:10 minutes). YouTube. Also available from Climatecentral.org, embedded in a related article.
- Smithsonian Institution Ocean Portal page on Ocean Acidification — this web page features three embedded videos on ocean acidification and its effects on marine organisms.
Ocean Acidification by the Alliance for Climate Education (3:02 minutes). ACE Science Shorts. Also on YouTube.
Oyster Farmers facing climate change (4:36 minutes). Produced by Benjamin Drummond and Sara Joy Steele. HD Vimeo.
- Ocean Acidification: An Ecosystem Facing Dissolution (5:01 minutes). Geomar. Helmholtz Centre for Ocean Research, Kiel. Also on YouTube.
- NOAA Earth System Research Laboratory, Global Monitoring Division, Recent Monthly Average Mauna Loa CO2.
- Daily Keeling Curve updates of CO2 concentrations at Mauna Loa Observatory, Hawaii (with links to graphs at various time scales), posted on the Scripps Institution of Oceanography website.
- Monthly mean CO2 data ftp file from NOAA.
- Annual average CO2 data ftp file from NOAA.
- Explore Greenhouse Gas (GHG) Emissions from Large Facilities (custom searches by state), from the US EPA.
- Keeling Curve Lessons (7 pages), from Scripps Institution of Oceanography.
- Teaching Essential Principle 6: Human activities are impacting the climate system., from CLEAN, describes how to teach about this essential principle and includes links to reviewed activities that address this topic.
- How do CO2 levels relate to ice ages and sea level?, an article by Rob Monroe, Scripps Institution of Oceanography.
- Carbon Dioxide Emissions from Power Plants Rated Worldwide from the Center for Global Development; article hosted by Science Daily.
- Carbon is costing us big time, by Charina Nadura, on BillMoyers.com's website.
- Ocean Acidification from NOAA's Pacific Marine Environmental Laboratory (PMEL) Carbon Program.
- Causes of climate change slide shows from US EPA.
- Global climate change impacts in the United States 2009 report, from the US Global Change Research Program.
- What we do: Assess the U.S. Climate, from Globalchange.gov.
- Global climate change indicators from the NOAA National Climatic Data Center.
- Carbon dioxide emission factors for coal, by B.D. Hong and E. R. Slatick, originally published in Energy Information Administration, Quarterly Coal Report, January–April 1994, DOE/EIA-0121(94/Q1) (Washington, DC, August 1994), pp. 1–8.
- Mauna Loa Observatory from the NASA Earth Observatory website.
- Biography of Charles David Keeling, from Scripps Institution of Oceanography.
- Time history of atmospheric carbon dioxide from 800,000 years ago to present from NOAA's Earth System Research Laboratory, Global Monitoring Division.
- Global Climate Change: The Effects of Global Warming, an activity from PBS Learning Media.
- UN Global warming report puts humans in the hot seat, by Kim Hjelmgaard and Doyle Rice, USA Today (Sept 27, 2013).
- Climate Change and Waste, from US EPA.
- A Year In The Life Of Earth's CO2, a 2014 article from NASA.
- Carbon Sequestration — Mineral carbonation in peridotite for CO2 capture and storage (CCS) , from The Earth Institute, Columbia University.