How This Sea Shell Knows the Weather in Greenland

Forams, tiny single-celled marine organisms, build shells from calcium carbonate. These shells contain oxygen isotopes that reveal historical climate data. By analyzing the ratio of regular to heavy oxygen in foram shells, scientists can infer past global temperatures and ice volumes. Forams have been recording this data for millions of years, providing a continuous climate record through sediment cores.

What can we learn from the ratio of regular oxygen to heavy oxygen in foram shells?

How do scientists use sediment cores to study past climate changes?