By Dilpreet Raju
Medill Reports

Thousands of meters of ice are kept in below-freezing temperatures so climate researchers can analyze what the Earth’s climate was like hundreds of thousands of years ago. Climatologists can then take bits of the ice, which hold thousands of years of undisturbed snow, to extract what concentrations of greenhouse gases like carbon dioxide and methane were for previous periods in the planet’s life.

The Earth’s surface temperature and concentrations of CO2 in the planet’s atmosphere are higher than ever, according to the National Oceanic and Atmospheric Administration. Ice cores provide valuable information to determine the impact of human involvement in climate change.

Dilpreet Raju is a master’s journalism candidate at Medill. You can follow him at @DilpreetRaju on Twitter or reach him at dilpreet@u.northwestern.edu.