Ice cores are scientists’ best source for historical climate data.

  • Claim

Every winter, some snow coating Arctic and Antarctic ice sheets is left behind and compressed into a layer of ice. By extracting cylinders of ice from sheets thousands of meters thick, scientists can analyze dust, ash, pollen and bubbles of atmospheric gas trapped inside. The deepest discovered ice cores are an estimated 800,000 years old. The particles trapped inside give scientists clues about volcanic eruptions, desert extent and forest fires. The presence of certain ions indicates past ocean activity, levels of sea ice and even the intensity of the Sun. The bubbles can be released to reveal the make-up of the ancient atmosphere, including greenhouse gas levels.

Photo credit: CSIRO


Name

Ice cores are scientists’ best source for historical climate data.

Description

An ice core is a core sample that is typically removed from an ice sheet or a high mountain glacier. Since the ice forms from the incremental buildup of annual layers of snow, lower layers are older than upper ones, and an ice core contains ice formed over a range of years. Cores are drilled with hand augers (for shallow holes) or powered drills; they can reach depths of over two miles (3.2 km), and contain ice up to 800,000 years old.

Types

Claim

Sources

NASA Global Climate Change: Vital Signs of the Planet

Topics

Causes of climate change