Different aspects of barium (Ba) chemistry can be used to probe the climate system. Particulate or solid phase biogenic barium (Babio) in deep-sea sediments is thought to be an archive of past biological productivity in the overlying water column, linking it directly to carbon uptake in surface waters.
Another promising use of Ba as a palaeoceanographic proxy comes in the form of the Ba/Ca ratio in the calcite of foraminifera, single-celled organisms that form shells from calcium carbonate. The Ba/Ca ratio of foraminiferal calcite has been linked to ocean alkalinity, weathering and circulation.
Dissolved Ba in the modern ocean can tell us about river and glacial inputs, biological production, and uptake of nutrients and carbon.