Exploring Paleoclimatology in the Classroom using Vostok Ice Core Data

The Vostok research station is located near the center of the Antarctic ice sheet (78°S 106°E). Ice core samples taken at the Vostok station are used to collect data on historical carbon dioxide levels. The data consist of measurements of the percentage of atmospheric gasses, such as CO₂ in fossil air bubbles that have been trapped in snow flakes and compressed into ice over 400,000 years old. Data are archived at NOAA's World Data Center for Paleoclimatology and represents geochemical data spanning 3,623 meters and over 400,000 years.

The Vostok station represents a collaboration between Russian, US, and French scientists. Ice cores taken from the Vostock station contain a record of atmospheric gas composition. Measurements of 'fossil' air trapped in bubbles in ice cores allow scientists to reconstruct historical fluctuations in green house gasses, such as CO₂. Measurements made on ice cores taken from the Vostok station provide a pre-historical record of CO₂ variations, providing a natural baseline that can be compared to current CO₂ levels (380 ppm) that are influenced by human activity. Studies of ice cores also provide a history of glacial cycles and ancient fluxations in atmospheric gas composition, with CO₂ levels ranging from 180 ppm during periods of lower temperatures to 280 ppm during warmer periods. Measurements of isotopes, such as deuterium, are also used as a proxy for temperature.

This dataset can be used to teach the following topics and skills in geochemistry and paleoclimatology:

• Methods for reconstructing historical climate change
• Ice ages and glacial cycles
• The use isotopic data as a proxy for temperature or age
• Global warming

• Using data to make graphs illustrating atmospheric changes over time
• Using mathmatical proccessing of datasets to determine relationships between temperature and CO₂ levels
• Comparing data from independent experiments to evaluate the relationship between carbon dioxide levels and temperature
• Using proxy data to create visual representations of glacial cycles
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  Starting Point describes an activity that uses Vostok Ice core data to recreate temperature from deuterium data.

Raw data are available in HTML tabular format for Vostok Ice core samples over a 400,000 year period. Available data include deuterium concentrations, oxygen isotope compositions, isotopic composition of O₂ and N₂, N₂0 levels and isotopic composition, sodium ion concentrations, CO₂ and methane levels, and ¹⁴C concentrations.

Users can choose a specific dataset of interest (such as methane levels) and download data in HTML tabular format (often from several different scientific sources).

• One way that students can proccess the data is to import raw data (provided in HTML tabular format) into a spreadsheet application such as Excel. Graphs could be generated to examine temporal changes in CO₂ concentrations. Calculations can also be made to estimate temperature using deuterium concentrations, as described in the Starting Point Vostok Ice Core Activity. Linear regression analyses could be performed to determine whether there is a statistically significant relationship between CO₂ levels and temperature.
• The Ice Core Gateway has a web-based browse and visualization tool, WebMapper (more info) , that can be used to create graphs. To use this feature, users can click on a geographic region and research station of interest. A pull down menu allows users to choose a measurement of interest (such as oxygen isotope or CO₂ levels), which can be downloaded in HTML tabular format and in some cases directly plotted.

• The Starting Point site provides a tutorial for using Excel.
• The Ice Core Data Gateway provides information on using WebMapper.

Ice core samples are obtained by drilling a long cylinder of ice (approximately 5 inches in diameter). The core is separated into 5 meter long segments and stored for further analyses. Electrical measurements are performed and stratigraphy is analyzed. Ice from the core is melted to measure the percentage of CO₂ and various chemical techniques such as mass spectrometry and gas chromatography are used to analyze isotopic composition.

Sources of error in reconstructing climate history using ice core data include determining age of the ice and correcting for gas exchange in snow prior to trapping of gas within bubbles enclosed in the compressed ice. Given the current understanding of glacial cycles, dating determined by techniques such as flow and compression modelling or using deuterium as a proxy for age yield robust measurements.

There are several research articles that describe the CO₂ record of the Vostok Ice Core data:

• Climate and atmospheric history of the past 420,000 years from the Vostok ice core,Antarctica. Petit et al. 1999. Nature: 429-436.
• Vostok ice core provides 160,000-year record of atmospheric CO₂. Barnola et al. 1987. Nature: 408-414.
• Ice Core Records of Atmospheric CO₂ Around the Last Three Glacial Terminations. Fischer et al. 1999. Science: 1712-1714.

• Starting Point describes an activity that uses Vostok Ice core data to recreate temperature from deuterium data.
• The WDC for Paleoclimatology maintains an education and outreach page with information on paleoclimatology, including an interactive Climate TimeLine Information Tool.

• The Ice Core Record: Past Archive of the Climate and Signpost to the Future: This review article from Philosophical Transactions of the Royal Society: Biological Sciences provides an extensive overview of ice core data and methods used for climate reconstruction. (Lorius et al., 1992)
• The journal Nature maintains a web focus that highlights numerous research articles and news reports related to ice core data.
• The Evolution of Climate Over the Last Millennium: This review article from Science discusses the role of paleoclimatology in understanding temperature oscillations and global warming. (Jones et al., 2001)
• Cloudy skies: assessing public understanding of global warming: This article from System Dynamics Review addresses the public perception of global warming and the politics of making policy changes. (Sterman and Sweeney, 2002).

• Starting Point contains numerous teaching activities, including concept tests and interactive lectures, related to Ice Ages, glacial cycles and climate change.
• Starting Point contains a Carbon Dioxide Exercise that allows students to explore recent changes in CO₂ using data from the Mauna Loa record.
• The Earth Exploration Toolbook contains a chapter on Exploring Regional Differences in Climate Change that uses data to model climate changes in two different regions of the United States.

• The NOAA website contains a collection of Paleo Perspectives (more info) on global climate change. Each 'Perspective' provides informative background content on climate change, access to relevant data, and links to relevant research articles and websites.
• The Law Dome Ice Core dataset from NOAA provides similar data on atmospheric gasses in the Antarctic.
• CO₂ data for the past 50 years are available for the Mauna Loa record from Hawaii and can be compared to Ice Core data.