What's an Ice Core?

Part of the Climate Change exhibition.

An ice core model in the exhibition is based on a real core from Greenland that is over 3 kilometers (1.9 miles) long. Cores drilled from Greenland's thick ice cap faithfully record the local climate over the past 108,000 years. The ice cap on Antarctica offers a climate record that stretches back even further, to 800,000 years.

Snow falls year-round over the ice sheets in Greenland and Antarctica, but summer snow and winter snow differ enough to be visible as distinct ice layers.

Ice cores provide a timeline of climate, with each year represented by a new layer formed on top of the ones from the year before. One way to date the layers is simply to start at the surface and count back the years.

The thickness of a layer—when compared to adjacent layers—gives a sense of how much snow fell at that spot in any one year.

A model of an ice core in the exhibition.
Denis Finnin/AMNH
Climate, On Ice

Ice cores can tell us a lot about ancient climates, including local temperature, CO2 concentration and, based on dust trapped in the ice, global and local wind patterns. These data, in turn, help us understand why and how the climate system changed in the past, how it works today, and how we might expect it to change in the future.