Iron Fertilization of the Subantarctic Ocean During the Last Ice Age

Abstract

Productive Dustiness The idea that biological productivity in the surface ocean is limited by a lack of available iron has been widely accepted, but it has been difficult to show that this effect might have operated in the geological past. Martínez-García et al. (p. 1347 ) investigated the isotopic composition of foraminifera-bound nitrogen in samples from an Ocean Drilling Project sediment core and found millennial-scale changes in nitrate consumption correlated with fluxes in the iron burial and productivity proxies over the past 160,000 years. Hence, in the Southern Ocean the biological pump was strengthened when dust fluxes were high, which explains a significant part of the difference in atmospheric CO 2 concentrations observed to occur across glacial cycles.