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Abstract

Marine phytoplankton growth at high latitudes is extensively limited by iron availability. Icebergs are a vector transporting the bioessential micronutrient iron into polar oceans. Therefore, increasing iceberg fluxes due to global warming have the potential to increase marine productivity and carbon export, creating a negative climate feedback. However, the magnitude of the iceberg iron flux, the subsequent fertilization effect and the resultant carbon export have not been quantified. Using a global analysis of iceberg samples, we reveal that iceberg iron concentrations vary over 6 orders of magnitude. Our results demonstrate that, whilst icebergs are the largest source of iron to the polar oceans, the heterogeneous iron distribution within ice moderates iron delivery to offshore waters and likely also affects the subsequent ocean iron enrichment. Future marine productivity may therefore be not only sensitive to increasing total iceberg fluxes, but also to changing iceberg properties, internal sediment distribution and melt dynamics.

Item Type:	Article
Authors/Creators:	Hopwood, MJ and Carroll, D and Hofer, J and Achterberg, EP and Meire, L and Le Moigne, FAC and Bach, LT and Eich, C and Sutherland, DA and Gonzalez, HE
Keywords:	iceberg, melting, carbon export, primary production, iron fertilisation
Journal or Publication Title:	Nature Communications
Publisher:	Nature Publishing Group
ISSN:	2041-1723
DOI / ID Number:	10.1038/s41467-019-13231-0
Copyright Information:	Copyright 2019 The Authors. Licensed under Creative Commons Attribution 4.0 International (CC BY 4.0) https://creativecommons.org/licenses/by/4.0/
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