This NASA animation presents the levels of atmospheric carbon dioxide over the last 400,000 years, last 1000 years and last 25 years at different time scales. The data come from the Lake Vostok ice cores (400,000 BC to about 4000 BC), Law Dome ice cores (1010 AD to 1975 AD) and Mauna Loa observations (1980 to 2005).

This NBC Learn video features climate scientists doing their research on Mt. Kilimanjaro to study the climate of the past. The scientists put the recently observed changes on the glacier into perspective by comparing past climate fluctuations, stressing that the current observed rate of change is unprecedented.

This video segment describes climate data collection from Greenland ice cores that indicate Earth's climate can change abruptly over a single decade rather than over thousands of years. The narrator describes how Earth has undergone dramatic climate shifts in relatively short spans of time prior to 8000 years ago. The video and accompanying essay provide explanations of the differences between weather and climate and how the climate itself had been unstable in the past, with wide variations in temperature occurring over decadal timescales.

This visualization graphically displays temperature and CO2 concentration in the atmosphere as derived from ice core data from 400,000 years ago to 1950. The data originates from UNEP GRID Arendal's graphic library of CO2 levels from Vostok ice core.

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

In this video, a PhD Student from the University of Maine explains how ice cores are used to study global climate change.

This interactive visualization describes how climatologists obtain and interpret evidence from the Greenland Ice Sheet in an effort to piece together a picture of Earth's distant climate history. Resource describes how glaciers form and how they can be used to collect ancient atmospheric data. The issues analyzed in the data collection are particularly good in showing how science is done in the field.

This narrated slide show gives a brief overview of coral biology and how coral reefs are in danger from pollution, ocean temperature change, ocean acidification, and climate change. In addition, scientists discuss how taking cores from corals yields information on past changes in ocean temperature.

In this activity, students reconstruct past climates using lake varves as a proxy to interpret long-term climate patterns and to understand annual sediment deposition and how it relates to weather and climate patterns.

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.