Jiang et al. (2024): Complexities of regulating climate by promoting marine primary production with ocean iron fertilization

Hai-Bo Jiang, David A. Hutchins, Hao-Ran Zhang, Yuan-Yuan Feng, Rui-Feng Zhang, Wei-Wei Sun, Wentao Ma, Yan Bai, Mark Wells, Ding He, Nianzhi Jiao, Yuntao Wang, Fei Chai IN: Earth-Science Reviews 249, 104675, https://doi.org/10.1016/j.earscirev.2024.104675

In the context of global climate change, ocean iron fertilization (OIF) has been suggested as a potential geoengineering strategy to enhance the growth of marine phytoplankton, subsequently promote the ocean carbon sink, and ultimately regulate atmospheric CO₂ and mitigate climate change. However, in past artificial OIF experiments, the elevation of both net primary production and carbon export to the deep ocean is far less than anticipated. This discrepancy can be attributed to several key factors that strongly influence the efficiency of OIF and biological carbon pump (BCP) including iron bioavailability and retention time, the sensitivity of phytoplankton to iron limitation, the influence of viruses and other microorganisms comprising the microbial carbon pump (MCP), and non-biological carbon cycles. Although previous reviews have extensively summarized the outcomes of the past OIF experiments, the mechanisms and key factors that influence climate regulation mediated by OIF have not been elucidated. In this review, the authors analyze these mechanisms throughout the whole process from OIF, to phytoplankton physiological responses, to carbon dioxide removal (CDR) and sequestration in the ocean, and ultimately to CDR in the atmosphere and its impact on climate change.

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