This video segment, from the 'Earth: The Operators' Manual' featuring climate expert Richard Alley, shows how ice cores stored at the National Ice Core Lab provide evidence that ancient ice contains records of Earth's past climate - specifically carbon dioxide and temperature.

This classroom resource is a combination of 3 visualizations and accompanying text that illustrate how 3 key natural phenomena - cyclical changes in solar energy output, major volcanic eruptions over the last century, and El Nino/Nina cycles - are insufficient to explain recent global warming.