How well do global ocean biogeochemistry models simulate dissolved iron distributions?

Alessandro Tagliabue, Olivier Aumont, Ros Death, John P. Dunne, Stephanie Dutkiewicz, Eric Galbraith, Kazuhiro Misumi, J. Keith Moore, Andy Ridgwell, Elliot Sherman, Charles Stock, Marcello Vichi, Christoph Völker, Andrew Yool

Research output: Contribution to journalArticleResearchpeer-review

134 Citations (Scopus)

Abstract

©2015. American Geophysical Union. All Rights Reserved. Numerical models of ocean biogeochemistry are relied upon to make projections about the impact of climate change on marine resources and test hypotheses regarding the drivers of past changes in climate and ecosystems. In large areas of the ocean, iron availability regulates the functioning of marine ecosystems and hence the ocean carbon cycle. Accordingly, our ability to quantify the drivers and impacts of fluctuations in ocean ecosystems and carbon cycling in space and time relies on first achieving an appropriate representation of the modern marine iron cycle in models. When the iron distributions from 13 global ocean biogeochemistry models are compared against the latest oceanic sections from the GEOTRACES program, we find that all models struggle to reproduce many aspects of the observed spatial patterns. Models that reflect the emerging evidence for multiple iron sources or subtleties of its internal cycling perform much better in capturing observed features than their simpler contemporaries, particularly in the ocean interior. We show that the substantial uncertainty in the input fluxes of iron results in a very wide range of residence times across models, which has implications for the response of ecosystems and global carbon cycling to perturbations. Given this large uncertainty, iron fertilization experiments based on any single current generation model should be interpreted with caution. Improvements to how such models represent iron scavenging and also biological cycling are needed to raise confidence in their projections of global biogeochemical change in the ocean.
Original languageEnglish
Pages (from-to)149-174
JournalGlobal Biogeochemical Cycles
Volume30
Issue number2
DOIs
Publication statusPublished - 1 Feb 2016

Keywords

  • biogeochemistry
  • climate
  • iron
  • model
  • ocean

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