How To Date an Ice Core

The age of an ice core is determined by a variety of techniques:

• Counting the annual layers (left) marked by differences in ¹⁸O, similar to counting tree rings to determine the age of the tree.

• Calibration by known historic events like volcanic eruptions and weapons testing.

• Dating the gas captured in the ice. This is done by retrieving the trapped gas and using either ¹⁴C or ³⁶Cl dating techniques to determine the age of the gas.

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