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Pre-industrial, present and future atmospheric soluble iron deposition and the role of aerosol acidity and oxalate under CMIP6 emissions
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  • Elisa Bergas-Massó,
  • Maria Gonçalves-Ageitos,
  • Stelios Myriokefalitakis,
  • Ron L. Miller,
  • Twan van Noije,
  • Philippe le Sager,
  • Gilbert Montané Pinto,
  • Carlos Pérez García-Pando
Elisa Bergas-Massó
Barcelona Supercomputing Center

Corresponding Author:[email protected]

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Maria Gonçalves-Ageitos
Universitat Politècnica de Catalunya,Barcelona Supercomputing Center - Centro Nacional de Supercomputación
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Stelios Myriokefalitakis
National Observatory of Athens
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Ron L. Miller
NASA Goddard Institute for Space Studies
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Twan van Noije
KNMI Royal Netherlands Meteorological Institute
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Philippe le Sager
KNMI Royal Netherlands Meteorological Institute
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Gilbert Montané Pinto
Barcelona Supercomputing Center
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Carlos Pérez García-Pando
Barcelona Supercomputing Center and ICREA
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Abstract

Changes in atmospheric iron (Fe) deposition to the open ocean affect net primary productivity, nitrogen fixation, and carbon uptake rates. We investigate the changes in soluble Fe (SFe) deposition from the pre-industrial period to the late 21st century using the EC-Earth3-Iron Earth System model, which stands out for its comprehensive representation of the atmospheric oxalate, sulfate, and Fe cycles. We show how anthropogenic activity has modified the magnitude and spatial distribution of SFe deposition by increasing combustion Fe emissions along with atmospheric acidity and oxalate levels. We find that SFe deposition has doubled since the early Industrial Era using the Coupled Model Intercomparison Project Phase 6 (CMIP6) emission inventory, with acidity being the main solubilization pathway for dust Fe, and ligand-promoted (oxalate) processing dominating the solubilization of combustion Fe. We project a global SFe deposition increase of 40% by the late 21st century relative to present day under Shared Socioeconomic Pathway (SSP) 3-7.0, which assumes weak climate change mitigation policies. In contrast, sustainable and business-as-usual SSPs (1-2.6 and 2-4.5) result in 35% and 10% global decreases, respectively. Despite these differences, SFe deposition consistently increases and decreases across SSPs over the (high nutrient low chlorophyl) equatorial Pacific and Southern Ocean (SO), respectively. Future changes in dust and wildfires with climate remains a key challenge for constraining SFe projections. We show that the equatorial Pacific and the SO would be sensitive not only to changes in Australian or South American dust emissions, but also to those in North Africa.