# Climate model: a century of Southern Ocean iron fertilization adds ~30 PgC uptake, below past estimates

- Published: 2026-11-07 16:31 UTC
- Section: Planet › Climate
- Tags: ocean iron fertilization, carbon dioxide removal, Southern Ocean, Earth System Model, carbon uptake durability, macronutrient drawdown, phytoplankton, PgC per year
- URL: https://realtech.media/news/rt-92af9a6ed990b9fe02688901_climate_model_a/

**Earth System Model simulations show sustained iron fertilization removes 0.3 PgC per year in the southern Southern Ocean, while global rates are 2–7 times lower than idealized estimates.**

![Climate model: a century of Southern Ocean iron fertilization adds ~30 PgC uptake, below past estimates](https://realtech.media/media/2026/11/4ebd7ca128b8aef4.jpg)
*ATSB, photo by ABIS Chris Beerens, RAN., Wikimedia Commons, CC BY 4.0*

A study in Science Advances used an Earth System Model to assess how much carbon large-scale ocean iron fertilization could remove and how long it would stay out of the atmosphere. The simulations ran under emissions-driven scenarios. The authors note that pathways limiting warming to 1.5–2 °C require emission cuts plus additional carbon dioxide removal of about 2–3 PgC per year [1].

## Uptake by region

According to the simulations, sustained fertilization over a century in the southern sector of the Southern Ocean gives a moderate contribution of about 30 PgC, or 0.3 PgC per year [1]. In other iron-limited regions, the additional uptake is largely offset, by 70–100%, by non-fertilized regions [1]. Global carbon removal rates come out 2–7 times lower than earlier idealized estimates [1].

## Durability and limits

When fertilization stops after 30 years, the ocean retains 50% of the additional carbon in the southern sector of the Southern Ocean, while retention in other regions is negligible [1]. The authors name several constraints: local and remote nutrient depletion, re-entrainment of previously sequestered carbon, incomplete macronutrient drawdown and reduced phytoplankton carbon-to-phosphorus ratios [1]. Incomplete macronutrient drawdown accounts for the largest difference from earlier studies. It reflects controls by light, top-down controls and the rate of macronutrient resupply [1].

The authors say that further assessment requires applying the standardized design across modeling institutions and analyzing top-down and bottom-up controls on nutrient drawdown.

## Sources

1. [Science Advances](https://doi.org/10.1126/sciadv.aed1631)

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Source: RealTech, realtech.media — https://realtech.media/news/rt-92af9a6ed990b9fe02688901_climate_model_a/