About ICe CORES

Ancient ice teaches us about our past and future climate

 Section of an ice core from the Greenland Ice Sheet Project (GISP), taken from 2129m below the surface. Credit: Peggy Weil and the National Ice Core Laboratory.

Section of an ice core from the Greenland Ice Sheet Project (GISP), taken from 2129m below the surface. Credit: Peggy Weil and the National Ice Core Laboratory.

Ice cores are cylinders of ice drilled from ice sheets and glaciers. Ice core records can provide extraordinarily detailed information about Earth's past climate. Under typical atmospheric conditions, snowfall is deposited across the ice sheet or glacier each year as the weather changes and is buried under the weight of snow that falls the next year. As each year’s snow moves deeper into the ice sheet, its coarse snow grains eventually become compressed into glassy layers of solid ice.

Seasonal differences in the snow properties and individual weather events like surface melting create visible layers, akin to rings in trees, and thus provide scientists with an invaluable long-term record of past snowfall amounts and indicate past climate conditions. Concentrations of sea salt, dust, soot, and other substances, as well as bubbles of ancient air trapped within the icy core layers, provide additional clues about local, regional, and even global patterns in Earth's oceans and atmosphere.

The Greenland Ice Sheet Project (GISP2) featured in 88 Cores recovered an ice core over two miles long, the deepest in the world at the time (in the early 1990s). The GISP2 ice core provided an extraordinarily precise and detailed record of at least 110,000 years of Earth’s climate history. Its retrieval marked the beginning of a new era in the field of paleoclimatology

Learn more here:
An Introduction to Ice Cores, NASA
Ice Cores 101, University of Maine
Greenland Ice Sheet Project (GISP2), University of Maine

Further reading:
The Two-Mile Time Machine, by Richard Alley
The Ice Chronicles, by Paul Andrew Mayewski and Frank White
"The Archive of Ice," by D. Graham Burnett