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 ~18 Sv (106 m3 s-1) in the northern North Atlantic and ~21 Sv (of which ~17 Sv enters the Pacific) in the Antarctic over the last mixing cycle of ~800 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 ~50% 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.