A threshold in the collapse and recovery of Atlantic Meridional Overturning Circulation under different interglacial conditions
(2023) ELI-Day 2023 — Location: Louvain-la-Neuve (25.May.2023)
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- Abstract
- Two equilibrium states are considered to exist in AMOC, which may rapidly push the current typical (‘on’) state to a collapsed (‘off’) state when the freshwater injection in the regions of deep-water formation across the threshold. Some simulation studies suggest that the threshold may be influenced by several factors, such as the region and the change rate of freshwater hosing. However, it is not fully clear to what extent the stability of the threshold could be affected by different interglacial boundary conditions. In this work, we conducted a set of sensitivity experiments with the Marine Isotope Stage 13 (the coolest interglacial over the last one million years) and the present interglacial boundary conditions employing two Earth system models, the Community Earth System Model and the LOVECLIM, to explore the AMOC and global climate response to freshwater hosing. Both models show a marked response of AMOC to a freshwater flux threshold of about 0.047 Sv in the Greenland-Iceland-Norwegian (GIN) seas. This threshold value is hardly affected by changes of orbital parameters or greenhouse gases between the two interglacials but is sensitive to hosing region and change rate of the freshwater. Further analysis reveals possible and apparent transitions of the magnitude and spatial pattern of the global climate response to freshwater hosing before and after the threshold during the MIS-13 interglacial. Our results imply that the relationship among AMOC, freshwater hosing and associated climate change during past interglacials could be a reference for future AMOC deceleration.
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Liu, W. (2023). A threshold in the collapse and recovery of Atlantic Meridional Overturning Circulation under different interglacial conditions. ELI-Day 2023, Louvain-la-Neuve. https://hdl.handle.net/2078.5/266480