STEM

Atmospheric CO2 and Temperature – what is normal? Plotting CO2

Before you begin: the gaseous contents of these bubbles trapped 1. Think about these questions and record your as “fossil air” in ancient layers of ice, we can answers on your own paper. use these data to determine past changes in a. What is climate and what is weather? CO2, especially during natural shifts in Earth’s b. How would you describe the climate climate prior to the influence of humans. With in your own town? these measurements of ancient greenhouse c. Does climate have any direct effects gasses, we are able to determine the real on your life? Does the climate impact of humans on the greenhouse gas change? (Ask your parents or concentration of our modern atmosphere. grandparents about climate changes Scientists also routinely measure stable they can recall.) hydrogen isotopes along the ice core. There is 2. Brainstorm and record some ideas for these a relationship between the ratio of different essential questions: hydrogen isotopes (2H and 1H) in the ice and a. How can we study climate changes? average annual temperature in Antarctica. b. What pieces of evidence can we look Because of this, we can calculate past for to see how the Earth’s climate temperatures at Vostok and compare it to the has changed over decades, CO2 content in atmosphere at the same time. centuries, millennia, and longer? Objectives Background During this activity, your class will Scientists travel the world to collect long, graph and analyze CO2 (carbon dioxide) and continuous ice cores from wherever they exist on temperature data from Vostok, Antarctica to our planet: ice caps, ice sheets, and glaciers. understand the human impact on greenhouse They do this as part of a “rescue operation” to gas (GHG) emissions and global warming. collect the thick sequences of ice that contain— layer after layer—information about the climate of Vocabulary: the past. The cores are collected using special Stable isotope Amplitude drilling equipment that doesn’t melt the ice. The Firn Frequency cores have to be stored and transported so they Snow metamorphism don’t melt in transit to a core repository for study. One of the largest ice core storage facilities in our Materials country is located in Denver at the US Geological Rulers, Graph paper, Pencils, Datasheet with Survey (http://nicl.usgs.gov/index.html). CO2 and age data Among the other common indices of atmospheric change we can measure from ice Activity cores are changes in greenhouse gases (GHGs: Your teacher will give you a datasheet with CO2 carbon dioxide, methane, water vapor, etc). concentrations of ice and the ages of the ice Well-mixed atmosphere routinely becomes sampled from cores taken from Vostok Station trapped in snow and firn (density < 0.83 in East Antarctica (The coldest recorded grams/cm3) as the firn compacts and temperature on Earth, -128.6°F (-89.2°C) was metamorphoses into ice (density: between 0.83 3 3 measured here on July 21, 1983). Your g/cm and 0.91 g/cm ), all of the air passages in datasheet contains only a small portion of the the firn pack are closed off. Compressing this data. Your classmates all have other portions. glacial ice does not displace the trapped gas Use your datasheet to plot the CO2 column (otherwise know as “fossil air”), rather the gas is versus ice “age” and connect the points on a also increasingly compressed into tight miniature sheet of graph paper. ice bubbles. Hence, if we are able to measure www.umassk12.net/ipy A STEM ED Program at the University of Massachusetts, funded by the National Science Foundation and supported by the Climate System Research Center in conjunction with the International Polar Year

STEM

Analysis I a. Describe what you see in your graph. b. What is the amplitude of CO2 concentration, i.e. what are the average highest and lowest values for CO2? When did they occur in time? c. Is there a cycle to the highs and lows? Or does CO2 simply increase or decrease? If there is a cycle, how far apart are the highest Extensions 1. Read and discuss “Global temperature highs or on what frequency do high CO2 concentrations occur? change” by Hansen et al, 2006 from Proceedings of the National Academy, Put it All Together Sept. 25, v. 103 2. Research and examine how temperature 1. As a class, assemble the long record of CO2 recorded in the ice in Antarctica. Answer the and CO2 relate to one another in the “Analysis” questions again, this time looking Greenland Ice Sheet and compare this at the full record. How are your http://www.globalwarmingart.com/images/8/88/Mauna_Loa_Carbon_Dioxide.png answers different and the same? record to Antarctica. 2. Now assemble the long record of 3. If we measured the CO2 trapped as fossil temperatures also recorded in ice cores and air in ice cores from Greenland and overlay it on your class’ CO2 record. Answer Antarctica would the gas content be the the “Analysis” questions again, this time same or different? Why? thinking about temperature. References: Analysis II Hansen, J., Mki. Sato, R. Ruedy, K. Lo, D.W. a. What is the relationship between CO2 and Lea, and M. Medina-Elizade 2006. Global global temperatures? temperature change. Proc. Natl. Acad. b. What is the normal range of variability of both Sci. 103, 14288-14293, CO2 and temperature? (over the past 1ka, doi:10.1073/pnas.0606291103. 100ka, 600ka) Keeling, Charles D. (1998). "Rewards and c. Now look at the atmospheric CO2 measured Penalties of Monitoring the Earth." Annual in the atmosphere by Ralph Keeling on Review of Energy and the Environment Mauna Loa since 1955 (chart to the right). 23: 25-82. d. What might cause seasonal changes in Petit, J.R., J. Jouzel, D. Raynaud, N.I. Barkov, GHGs? Why is there a pattern? J.-M. Barnola, I. Basile, M. Benders, J. e. What is the current level of CO2 in the Chappellaz, M. Davis, G. Delayque, M. atmosphere today? Delmotte, V.M. Kotlyakov, M. Legrand, f. Is this value in the normal range of your data V.Y. Lipenkov, C. Lorius, L. Pépin, C. from Vostok? Ritz, E. Saltzman, and M. Stievenard. g. How much of the modern greenhouse gas 1999. Climate and atmospheric history of change is natural and how much of it is us? the past 420,000 years from the Vostok h. What can we do about CO2? List some ideas ice core, Antarctica. Nature 399: 429-436 you have or what you have heard discussed in the media or in the news.

www.umassk12.net/ipy A STEM ED Program at the University of Massachusetts, funded by the National Science Foundation and supported by the Climate System Research Center in conjunction with the International Polar Year