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 well-designed experiment compares CO2 impacts on salt water and fresh water. In a short demonstration, students examine how distilled water (i.e., pure water without any dissolved ions or compounds) and seawater are affected differently by increasing carbon dioxide in the air.