On the relationship between Nd isotopic composition and ocean overturning circulation in idealized freshwater discharge events

Using a cost‐efficient climate model, the effect of changes in overturning circulation on neodymium isotopic composition, ϵ Nd , is systematically examined for the first time. Idealized sequences of abrupt climate changes are induced by the application of periodic freshwater fluxes to the North Atlantic (NA) and the Southern Ocean (SO), thus mainly affecting either the formation of North Atlantic Deep Water (NADW) or Antarctic Bottom Water (AABW). Variations in ϵ Nd reflect weakening and strengthening of the formation of NADW and AABW, changes in ϵ Nd of end‐members are relatively small. Relationships between ϵ Nd and the strength of NADW or AABW are more pronounced for AABW than for NADW. Atlantic patterns of variations in ϵ Nd systematically differ between NA and SO experiments. Additionally, the signature of changes in ϵ Nd in the Atlantic and the Pacific is alike in NA but opposite in SO experiments. Discrimination between NA and SO experiments is therefore possible based on the Atlantic pattern of variations in ϵ Nd and the contrariwise behavior of ϵ Nd in the Atlantic and the Pacific. In further experiments we examined the effect of variations in magnitudes of particle export fluxes. Within the examined range, and although settling particles represent the only sink of Nd, their effects on ϵ Nd are relatively small. Our results confirm the large potential of ϵ Nd as a paleocirculation tracer but also indicate its limitations of quantitative reconstructions of changes in the Atlantic Meridional Ocean Circulation.