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 animation shows predicted changes in temperature across the globe, relative to pre-industrial levels, under two different emissions scenarios in the COP 17 climate model. The first is with emissions continuing to increase through the century. The second is with emissions declining through the century.

This video is one of a seven, Climate Change: Lines of Evidence series, produced by the the National Research Council. It outlines and explains what evidence currently exists in support of humans playing a role in contributing to the rise in atmospheric carbon dioxide levels.

This short video illustrates the phenomena of El NiÃo and La NiÃa: their relationships to tradewinds and surface water temperatures, and their effects on precipitation in North America.

This is a video overview of the history of climate science, with the goal of debunking the idea that in the 1970s, climate scientists were predicting global cooling.

This short video, adapted from NOVA, explains how Earth's position relative to the Sun might be responsible for the dramatic shift in the climate of what is now the Saharan nation of Djibouti.

This National Geographic video explains the origins of the El NiÃo Southern Oscillation using animations and shows the impacts on humans, wildlife and habitat, particularly in the United States.

This multi-part activity introduces users to normal seasonal sea surface temperature (SST) variation as well as extreme variation, as in the case of El NiÃo and La NiÃa events, in the equatorial Pacific Ocean. Via a THREDDS server, users learn how to download seasonal SST data for the years 1982 to 1998. Using a geographic information system (GIS), they visualize and analyze that data, looking for the tell-tale SST signature of El NiÃo and La NiÃa events that occurred during that time period. At the end, students analyze a season of their own choosing to determine if an El NiÃo or La NiÃa SST pattern emerged in that year's data.

In this learning activity, students use a web-based geologic timeline to examine temperature, CO2 concentration, and ice cover data to investigate how climate has changed during the last 715 million years.

This is a classroom activity about the forcing mechanisms for the most recent cold period: the Little Ice Age (1350-1850). Students receive data about tree ring records, solar activity, and volcanic eruptions during this time period. By comparing and contrasting time intervals when tree growth was at a minimum, solar activity was low, and major volcanic eruptions occurred, they draw conclusions about possible natural causes of climate change and identify factors that may indicate climate change.