A recent study has revealed that dust deposition plays a crucial role in sustaining one-third of the productivity in the Southern Ocean. This natural process of iron fertilization by windblown dust has long been believed to enhance biological productivity and influence the climate. However, until now, the extent of this phenomenon had never been measured across the Southern Ocean on an annual basis.
For the study, researchers combined data from 11 years of nitrate observations gathered by autonomous biogeochemical ocean profiling floats with a simulation of dust distribution in the Southern Hemisphere. By doing so, they were able to empirically establish the connection between dust-iron deposition and annual net community production (ANCP) in the iron-limited Southern Ocean. This allowed them to determine the biological response to dust-iron in the open waters of the perpetually ice-free region of the Southern Ocean both in the present time and during the last glacial maximum (LGM).
Their findings showed that dust-iron currently contributes to supporting 33% – or more precisely, 15% – of the ANCP in the Southern Ocean. This means that a significant portion of the biological activity in this oceanic region is made possible by the deposition of iron carried by dust particles through the wind. However, when looking back at the LGM, a time when dust deposition was significantly higher than it is now, the contribution of dust to the ANCP was even more substantial, estimated at around 64%, with a margin of error of 13%.
This study provides groundbreaking evidence of the widespread effect of dust-iron fertilization of the Southern Ocean. By quantifying the impact of dust deposition on biological productivity at both present and past periods, the researchers have highlighted the importance of dust in the carbon cycle and climate dynamics of the planet.
The results of this research support the theory that dust plays a significant role in driving biological productivity and regulating the climate of the Southern Ocean. The study suggests that variations in dust deposition over glacial to interglacial timescales can have a major impact on the functioning of this ecosystem and, by extension, on global carbon cycling processes. These findings shed new light on the intricate relationship between dust, iron, biological productivity, and climate in the Southern Ocean.
