Nearly a million years of ice and atmosphere are stored in this Colorado lab

The National Science Foundation banks thousands of meters of ice dating back across nearly 1 million years, invaluable markers to document rapid global warming now.

By Dilpreet Raju, June 14, 2023 – 

Thousands of meters of ice banked in below-freezing temperatures allow climate researchers to analyze what the Earth’s climate was like hundreds of thousands of years ago and document the rapidly accelerating rise of carbon emissions, the thermostat driving global warming. Climatologists can then take bits of the ice, which hold thousands of years of undisturbed snow, to extract ancient air and measure concentrations of greenhouse gases like carbon dioxide and methane in previous periods of the planet’s life.

Earth’s surface temperature and concentrations of CO2 in the planet’s atmosphere are higher than ever now, according to the National Oceanic and Atmospheric Administration. The ice cores show CO2 levels at about 200 ppm during ice ages that rose up to 300 ppm during warm spells across nearly a million years. Now, the levels read 425 ppm. 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

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