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 interactive visualization from the NASA Earth Observatory website compares Arctic sea ice minimum extent from 1984 to that of 2012.

This is a multi-faceted activity that offers students a variety of opportunities to learn about permafrost through an important sink and source of greenhouse gas (methane), about which most students living in lower latitudes know little.

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.

In this activity, students examine the effects of hurricanes on sea surface temperature using NASA data. They examine authentic sea surface temperature data to explore how hurricanes extract heat energy from the ocean surface.

This is a figure from the 2007 IPCC Assessment Report 4 on atmospheric concentrations of carbon dioxide, methane and nitrous oxide over the last 10,000 years (large panels) and since 1750 (inset panels).

This video, from ClimateCentral, features a team of scientists from the Northern Greenland Eemian Ice Drilling Project (NEEM), who study atmospheric air bubbles trapped in an ice core from a period in Greenland's ice sheet which began about 130,000 years ago and lasted about 10,000 years; a period known as the Eemian. The air bubbles from the ancient atmosphere - all aligned on the same time scale - reveal what happened with climate change over that period of time.

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 lesson, students examine and interpret varied observational datasets and are asked to determine whether the data supports or does not support the statement: climate change is occurring in Colorado.

This short video discusses where carbon dioxide, the gas that is mainly responsible for warming up our planet and changing the climate, comes from. It discusses how the rise in atmospheric carbon dioxide comes directly from the burning of fossil fuels and indirectly from the human need for energy.