Abstract

Over recent decades the micronutrient iron has been demonstrated to play an important role in regulating ocean productivity, carbon export and the more general biogeochemical cycling of carbon and other nutrients. Due to its role in modulating the biological pump in the Southern Ocean, iron availability also exerts a degree of control on atmospheric carbon dioxide levels. This has led to speculation about past control of climate across glacial and interglacial cycles by changes in just iron delivery to the Antarctic oceans. In this seminar I will use numerical modelling results and observational syntheses to examine a number of these aspects of the iron cycle. For example, how do different sources of iron to the ocean modulate atmospheric carbon dioxide levels and why do glacial conditions resulting in a relatively weak effect when tested in state of the art models? I will examine the vertical profile of iron in some detail and quantify how iron is transported to the mixed layer in the Southern Ocean to be used by the biota, which enables us to generalise a seasonal cycle of iron supply and demand. Finally, a number of future challenges and ongoing studies for the better understanding of how iron is cycled in the ocean will be summarised.