Lower oceanic ????13C during the Last Interglacial compared to the Holocene

• Main Authors: Bengtson, Shannon A., Menviel, Laurie C., Meissner, Katrin J., Missiaen, Lise, Peterson, Carlye D., Lisiecki, Lorraine E., Joos, Fortunat
• Format: Text
• Language: English
• Published: 2020
• Subjects: NADW; North Atlantic Deep Water; North Atlantic
• Online Access: https://doi.org/10.5194/cp-2020-73; https://cp.copernicus.org/preprints/cp-2020-73/

The last time in Earth’s history when the high latitudes were warmer than during pre-industrial times was the last interglacial (LIG, 129–116 ka BP). Since the LIG is the most recent and best documented warm time period, it can provide insights into climate processes in a warmer world. However, some key features of the LIG are not well constrained, notably the oceanic circulation and the global carbon cycle. Here, we use a new database of LIG benthic ???? 13 C to investigate these two aspects. We find that the oceanic mean ???? 13 C was ~ 0.2 ‰ lower during the LIG (here defined as 125–120 ka BP) when compared to the mid-Holocene (7–4 ka BP). As the LIG was slightly warmer than the Holocene, it is possible that terrestrial carbon was lower, which would have led to both a lower oceanic ???? 13 C and atmospheric ???? 13 CO 2 as observed in paleo-records. However, given the multi-millennial timescale, the lower oceanic ???? 13 C most likely reflects a long-term imbalance between weathering and burial of carbon. The ???? 13 C distribution in the Atlantic Ocean suggests no significant difference in the latitudinal and depth extent of North Atlantic Deep Water (NADW) between the LIG and the mid-Holocene. Furthermore, the data suggests that the multi-millennial mean NADW transport was similar between these two time periods.