Clam shells detail millennium of change
14 Dec 2016 by hdqwhmhjjm.d hdqwhmhjjm.d
A US scientist has created, for the first time, a 1,000 year record of ocean climate change – using clam shells.
A US scientist has created, for the first time, a 1,000 year record of ocean climate change – using clam shells.
Thousands of clams, some of which can live up to 500 years, were taken from seawater on the North Icelandic Shelf. Researchers studied annual growth increments in the shell, similar to tree trunk rings, to understand how ocean conditions changed.
Alan Wanamaker, associate professor at Iowa State University, and co-author, said: “The coolest thing that came out of this record is that during the first 800 years of data, ocean changes seemed to be leading atmospheric changes, or the changes were at least simultaneous. But after 1800 and the industrial revolution, the atmosphere seemed to take complete control.”
Based on a decade of work and requiring almost 1,500 isotope samples from clams, the study details climate change from 953AD to 2000. In order to complete this, Wanamaker used radiocarbon dating as well as determining oxygen isotopes on the clam shells. Heavier oxygen isotopes are linked to colder, dense seawater and vice versa for lighter isotopes.
This research has also allowed researchers to study have temperature, density and circulation changes have affected changes in a wider climate system. Currently, Wanamaker’s study group is currently collecting and analysing clam shells from Norway and Maine in order to investigate changes in those oceans over time.
The study was published in Nature Communications.
