In this activity, students use datasets from both the Northern and Southern hemispheres to observe seasonal and hemispheric differences in changes to atmospheric C02 release and uptake over time.

In this short video from ClimateCentral, host Jessica Harrop explains what evidence scientists have for claiming that recent global warming is caused by humans and is not just part of a natural cycle.

This NASA animation shows the levels of atmospheric carbon dioxide over different time scales. Viewers can compare the last 400,000 years, last 1000 years, and last 25 years. 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 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.

Key figure from the 2007 Intergovernmental Panel on Climate Change (IPCC) report that shows changes in global average surface temperature, global average sea level, and Northern Hemisphere snow cover from as far back as 1850.

This video describes why tropical ice cores are important and provide different information than polar ice cores, why getting them now is important (they are disappearing), and how scientists get them. The work of glaciologist Lonnie Thompson is featured, with a focus on his work collecting cores of ice from high mountain glaciers that contain significant data about past climate change.

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 collection of photos from the NASA Climate website features images of global change, such as floods, wildfires, and retreating glaciers. Not all images show change caused directly by climate change and energy use, and descriptive captions indicate causes for change in most of the images.

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.

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