Ice Cores

The video above shows the National Ice Core Lab located in Colorado, where ice cores are stored and studied. 

Ice Core Proxy

Source:http://epo.sonoma.edu/EposChronicles/wp-content/uploads/2011/02/ice_core.jpg

Ice cores are a way that scientists are able to tell about past climates on Earth. Within each core that is taken, layers from each previous year created from layers of snow accumulation can be studied to see what was happening on the Earth. As shown in the image above, the air bubbles that are trapped can be studied to learn about different aspects of the climate. The link below provides more information about ice cores and how they are used as a proxy for the climate. 

Ice Core Proxy