Fast recovery of North Atlantic sea level in response to atmospheric CO2 removal

Abstract

Human-induced increases in atmospheric carbon dioxide (CO2) cause global warming, which leads global mean sea level rise. Previous research has shown that even with the reduction or removal of atmospheric CO2, the global mean sea level will not return to its initial level. However, the regional effects of reducing or removing atmospheric CO2 on sea level change have not been extensively studied. In this study, we analyzed global and regional sea level changes over a 560-year period, including 140 years of a linear increase in atmospheric CO2 of 1% per year, followed by 140 years of a linear decrease, and finally 280 years of maintenance at pre-industrial CO2 levels. Our analysis showed that the sea level in the North Atlantic region increased rapidly relative to the global mean, and then recovered rapidly. We attribute these variations to fluctuations in the Atlantic Meridional Overturning Circulation (AMOC). As the AMOC weakened, heat and salt were trapped in the lower latitudes of the North Atlantic region, resulting in a slower transfer of these elements to higher latitudes. As the AMOC recovered and overshoot, the accumulated heat and salt were rapidly transferred to higher latitudes, resulting in changes in sea level. Our results suggest that the North Atlantic region is more sensitive to changes in atmospheric CO2 compared to the global mean. The North Atlantic region has a high population density and is expected to suffer significant damage as a result of sea level change. Therefore, continuous research on sea level change in this region is needed, and our study could help improve the ability to predict future sea level change in this area.