This video is part two of a seven-part National Academies series, Climate Change: Lines of Evidence. The video outlines, with the use of recent research and historical data, how we know that the Earth is warming.

This short video describes how the compression of Antarctic snow into ice captures air from past atmospheres. It shows how ice cores are drilled from the Antarctic ice and prepared for shipment and subsequent analysis.

This video shows where and how ice cores are extracted from the West Antarctic Ice Sheet (WAIS), cut, packaged, flown to the ice core storage facility in Denver, further sliced into samples, and shipped to labs all over the world where scientists use them to study indicators of climate change from the past.

In this exercise learners use statistics (T-test using Excel) to analyze an authentic dataset from Lake Mendota in Madison, WI that spans the last 150 years to explore ice on/ice off dates. In addition, students are asked to investigate the IPCC Likelihoodscale and apply it to their statistical results.

This series of visualizations show the annual Arctic sea ice minimum from 1979 to 2010. The decrease in Arctic sea ice over time is shown in an animation and a graph plotted simultaneously, but can be parsed so that the change in sea ice area can be shown without the graph.

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 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 activity uses geophysical and geochemical data to determine climate in Central America during the recent past and to explore the link between climate (wet periods and drought) and population growth/demise among the Maya. Students use ocean drilling data to interpret climate and to consider the influence of climate on the Mayan civilization.

This short video clip summarizes NOAA's annual State of the Climate Report for 2009. It presents a comprehensive summary of Earth's climate in 2009 and establishes the last decade as the warmest on record. Reduced extent of Arctic sea ice, glacier volume, and snow cover reflect the effects of rising global temperature.

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.