In this audio slideshow, an ecologist from the University of Florida describes the radiocarbon dating technique that scientists use to determine the amount of carbon within the permafrost of the Arctic tundra. Understanding the rate of carbon released as permafrost thaws is necessary to understand how this positive feedback mechanism is contributing to climate change that may further increase global surface temperatures.

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

This static graph of changes in CO2 concentrations goes back 400,000 years, showing the dramatic spike in recent years.