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.

In this 6-part activity, students learn about climate change during the Cenozoic and the abrupt changes at the Cretaceous/Paleogene boundary (65.5 million years ago), the Eocene/Oligocene boundary (33.9 million years ago), and the Paleocene/Eocene boundary (55.8 million years ago).