OC3 scientific goals
OC3 was active from 2014 to 2019.
Stable carbon and oxygen isotopes (δ13C, δ18O) are routinely measured on shells of fossil benthic foraminifera and have been used for a long time as a proxy to infer both carbon cycling as well as deep ocean circulation in the past. A large number of data has therefore been measured. However, δ13C is determined by air-sea gas exchange as well as by biological processes, which made unequivocal interpretations difficult. Moreover, a global assessment of how reliably different species of foraminifera represent the water column has not been undertaken. These difficulties may have led to many measurements being unpublished and unreported. Fortunately, in recent years, process based models including δ13C have been developed and a new global dataset of water column δ13C measurements has been compiled.
The group created a project to synthesize down-core δ13C data and δ18O data from benthic foraminifera, including unpublished and unreported data. Down-core data revealed changes in ocean circulation and carbon cycling and was useful for comparison with other paleodata (e.g. from ice cores or speleothems) and transient model simulations. Focus of the down-core compilation was on the last glacial cycle and in particular on the last deglaciation.
Specific scientific questions addressed were:
How did the deep ocean circulation change during the last deglaciation?
How did ocean carbon cycling and storage change during the last deglaciation?
How did deglacial changes in ocean circulation and carbon cycle affect climate and atmospheric CO2?
Expected output and products during the 2019 extenion
1. Fully documented dataset of benthic d13C and d18O measurements, including complete and raw down-core data and used age constraints.
2. Ancillary planktic data (14C) will be collected for age model constrains.
3. Following publications are expected: One data base description paper, regional deep-water circulation papers from the North and South Atlantic Group, one global synthesis paper.
