Early in the 16th century, the last colonist died. In 1540, ships driven to Greenland by severe weather found no one left alive, and one dead man frozen where he had fallen. Studies of oxygen locked within the enamel of the Viking teeth reveal that Greenland's once balmy climate turned frigid, sealing the colony's fate. Henry C. Fricke of the University of Michigan in Ann Arbor and his colleagues are the first researchers to decipher information about past climates using isotopic evidence from human bodies. While geochemists often use oxygen isotopes to reconstruct conditions, they typically analyze oxygen from non-biological materials such as seafloor sediments, soil, or ancient ice.
People are interested in humans and their relationship to climate change.
That isotopic ratio, in turn, indicates the local temperature. Fricke and his coworkers looked at 29 teeth uncovered at three archaeological sites in Greenland and one in Denmark. Next, the researchers looked at how ratios changed over time in souther Greenland. By comparing teeth from the year 1100 with those from 1450, they found that mean annual temperatures dropped by about 1.5C, which would have had significant effects, says Fricke. They reported their findings late last month at a meeting of the Geological Society of America in Seattle.