AMOC changes over the past 2000 years: insights from marine proxy records and a simulation with a sea-ice-ocean model

The Atlantic Meridional Overturning Circulation (AMOC) is a key modulator of global climate and constitutes one of the tipping point elements in the context of anthropogenic climate change. Recent studies have identified an ongoing AMOC slowdown, potentially leading to a collapse which would have substantial climatic and societal impacts. However, the shortness of instrumental record is too limited to capture the full variability of the AMOC, and to delineate the contribution of internal variability from the impact of anthropogenic climate change. In this study, we attempt to put recent AMOC changes in a long-term context by assessing its variability over the past 2000 years. To this end, we compile marine proxy reconstructions from the North Atlantic to identify coherent signals over periods of known climatic perturbations such as the Roman Warm Period, the Medieval Warm Period and the Little Ice Age and to determine their potential relationship with the AMOC state. Further, we compare these reconstructions with outputs from a transient numerical simulation over 1700-2023 AD run with the NEMO – SI³ global ocean-sea ice model, forced by a paleo-based atmospheric reconstruction, to identify ocean circulation changes across the termination of the Little Ice Age and under modern global warming.