Lower oceanic δ 13 C during the last interglacial period compared to the Holocene

摘要

The last time in Earth's history when high latitudes were warmer than during pre-industrial times was the last interglacial period (LIG, 129–116?ka?BP). Since the LIG is the most recent and best documented interglacial, 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 δ 13 C to investigate these two aspects. We find that the oceanic mean δ 13 C was ～ ?0.2?‰ lower during the LIG (here defined as 125–120?ka?BP) when compared to the Holocene (7–2?ka?BP). A lower terrestrial carbon content at the LIG than during the Holocene could have led to both lower oceanic δ 13 C and atmospheric δ 13 CO 2 as observed in paleo-records. However, given the multi-millennial timescale, the lower oceanic δ 13 C most likely reflects a long-term imbalance between weathering and burial of carbon. The δ 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 Holocene. Furthermore, the data suggest that the multi-millennial mean NADW transport was similar between these two time periods.