Constraints on deep-water formation from the oceanic distributions of ¹⁰Be

An analysis of the oceanic distribution of cosmogenic ¹⁰Be shows that deep waters are formed by descending of cold, dense surface waters at a rate of Ο18 Sv (10⁶ m³ s^-1) in the northern North Atlantic and Ο21 Sv (of which Ο17 Sv enters the Pacific) in the Antarctic over the last mixing cycle of Ο800 years, lending support to the estimates based on radiocarbon and nutrient distributions. It also indicates that deep-water production in the northern North Atlantic is Ο50% higher averaging over the recent <100 years than over the last mixing cycle, suggesting a possible increase in the thermohaline ventilation of the North Atlantic during the past century.