In this activity, students will use oxygen isotope values of two species of modern coral to reconstruct ambient water temperature over a four-year period. They use Microsoft Excel, or similar application, to create a spreadsheet of temperature values calculated from the isotope values of the corals by means of an algebraic equation. Students then use correlation and regression techniques to determine whether isotope records can be considered to be good proxies for records of past temperatures.

Students gain experience using a spreadsheet and working with others to decide how to conduct their model 'experiments' with the NASA GEEBITT (Global Equilibrium Energy Balance Interactive Tinker Toy). This activity helps students become more familiar with the physical processes that made Earth's early climate so different from that of today. Students also acquire first-hand experience with a limitation in modeling, specifically, parameterization of critical processes.

This set of activities is about carbon sources, sinks, and fluxes among them - both with and without anthropogenic components.