Late Holocene increase in influence of Pacific deep water off southern Chile caused by migration of the Southern westerly wind: Evidence from beryllium isotopes

The Southern Hemisphere westerly winds and the Antarctic Circumpolar Current, both located offshore Chile, are key components of global climate due to their influence on Southern Ocean upwelling and nutrient utilization with implications for atmospheric CO2. In this study, the Holocene upwelling history of the Chilean continental margin is reconstructed using beryllium isotopes in the reactive phase of marine sediments collected off the coast of southern Chile. The increase in 10Be/9Be throughout the Holocene reflects the strengthening of coastal upwelling due to the southward shift of the Southern Hemisphere westerly winds, which is consistent with increased productivity along the Chilean margin. These observed changes support the idea that complete utilization of nitrate, exported from the Southern Ocean, likely acted to reduce the Southern Ocean's contribution to the increase in atmospheric CO2 during the Holocene.