Exploring Paleoclimatology in the Classroom Using Coral Radioisotope Data from Rarotonga Island in the South Pacific

Access Coral Radioisotope Data from the Homepage for the World Data Center for Paleoclimatology

This page was created for SERC by Heather Rissler.

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The Dataset

Coral Radioisotope Data from the Homepage for the World Data Center for Paleoclimatology provides users with access to atomic ratio data (Sr/Ca) and Sea Surface Temperature (SST) data for coral samples near Rarotonga Island in the South Specific gyre. The dataset covers a 271 year period and is presented in graphical and raw text formats.

Use and Relevance

Reconstructing past climate histories is vital for understanding and predicting global climate change. Paleoclimatology provides data that can be used to determine climatic variations including historical changes in temperature. In the case of coral reefs, carbon dating of samples can be used to estimate sample age while the ratio of strontium and calcium can be used as a record of SST changes. The Coral Radioisotope Data demonstrate how isotopic data and atomic ratios can be used to obtain an accurate picture of oceanic temperature oscillations.

Use in Teaching

This dataset can be used to teach the following skills and topics Paleoclimatology, Physical Oceanography, and Biogeochemistry:


  • Methods for reconstructing temperature records
  • South Pacific gyre
  • El Niño Southern Oscillation
  • Relevance of decadal variations in sea surface temperature


  • Using data to generate graphs comparing Sr/Ca ratios to historical temperature data
  • Calculating statistical relationship between Sr/Ca ratios and empirical temperature data
  • Using linear regression analyses to compare and evaluate methods for reconstructing climate history
  • Interpreting chemical data from coral samples

Exploring the Data

Data Type and Presentation

Data for Sr/Ca ratios and SST are provided for the period from 1726-1997. Data are available in raw format (as a text file) and in graphical form (as a JPEG image).

Accessing the Data

Raw data can be accessed via ftp. A description of the data, including graphical representations, is archived at the Paleoclimatology branch of the NOAA website.

Manipulating Data and Creating Visualizations

One way that students can process the data is to create graphs from raw data (provided text files) using a spreadsheet application such as Excel.

Tools for Data Manipulation

Raw data can be downloaded and imported into a spreadsheet application such as Excel for further processing. The Starting Point site provides a tutorial for using Excel. Linear regression analysis can be performed to examine the robustness of the relationship between Sr/Ca ratios and SST.

About the Data

The Story Behind the Data

A non-technical narrative describing the data collection and scientific process is provided in a 'data story' from CIRES.

Collection Methods

A hydraulic drill was used to extract a core sample from coral growing 18.3 m off of Rarotonga Island (21°14'11"S, 159°49'59"W). Sr/Ca ratios for a 271 year period were determined by performing atomic emission spectroscopy on 1 mm intervals of a 3.5 m core sample extracted from Porites lutea coral colonies in 1997. Measured SST data was obtained from Integrated Global Ocean Service System Products (IGOSS).

Limitations and Sources of Error

Limitations to climate reconstruction depend on the methodology used. Sr/Ca ratios as well as oxygen isotope data can be used to calculate SST with an accuracy near 0.5°C.

For More Detail

More complete information about the data is available in question/answer format from CORIS.

References and Resources

Scientific References that Use this Dataset

Other Related Scientific References

Other related Education Resources

  • Air-sea Interactions: Activities in Oceanography: An example from Teaching Quantitative Skills in the Geosciences site that includes a module on the El Nino Southern Oscillation.
  • An activity related to Coral Bleaching is described in a data tip from Bridge, the Ocean Sciences Education Resource Teacher Center archive.

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