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 series of visualizations show the annual Arctic sea ice minimum from 1979 to 2015. 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.

This video describes how field research -- in this case, making water measurements in rugged mountain locations -- helps us to understand the complex relationships among changing climate, populations, and water usage.

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.

The Greenland 2014: Follow the Water video is about Greenland's ice sheet, accompanied by computer models of the same, to show how the ice is melting, where the meltwater is going, and what it is doing both on the surface and beneath the ice.