Lethal by Design? Resolving Differences Between Experimental and Real‐World Alkalinity Perturbations in Ocean Alkalinity Enhancement
- 1Institute for Marine and Antarctic Studies University of Tasmania Hobart TAS Australia
- 2Google Inc. WA WA USA
- 3Department of Oceanography Dalhousie University Halifax NS Canada
Abstract
Ocean alkalinity enhancement (OAE) aims to mitigate climate change by increasing the chemical capacity of seawater to store anthropogenic CO 2 . OAE can be implemented through multiple pathways, each of which intentionally modifies marine carbonate chemistry through increases in total alkalinity (TA). Experimental research has only recently begun to assess how such TA perturbations (ΔTA) and associated carbonate chemistry changes affect ocean ecosystems. Meaningful assessments need context on how ΔTA‐induced by different OAE pathways would evolve over time and in magnitude. Here, we use a dilution equation, a regional model, and a global model to explore how marine organisms would be exposed to ΔTA under realistic constraints. We find that a more extreme ΔTA of>1,000 μmol kg −1 , a perturbation common in OAE experiments, only occurs for minutes in a minuscule fraction of the OAE‐perturbed seawater volume. In contrast, ΔTA between 1 and 100 μmol kg −1 is a ubiquitous perturbation range for OAE under real‐world constraints, yet are not commonly in focus of environmental OAE assessments. These results suggest that there is a disconnect between real‐world ΔTA that can plausibly be invoked by OAE and the experimental ΔTA range frequently used in the environmental OAE assessment. While “unrealistic” ΔTA can provide mechanistic insights into an organism or ecosystem response to carbonate chemistry changes, they can also cause overestimation of OAE effects, if the unrealistic ΔTA is not contextualized appropriately. Our results can be used to improve the contextualization of OAE studies, thereby making the interpretation of ΔTA effects on the environment more robust.
Related
- Response of the Carbonate System to Ocean Alkalinity Enhancement: A Mesocosm-Scale Experiment
- Impacts of simulated coastal ocean alkalinity enhancement on the seasonal carbon cycle in European waters under a low- and a high-emission scenario
- The Ecological Activity Index tool for mapping potential ecosystem exposure to ocean alkalinity enhancement
- The efficiency and ocean acidification mitigation potential of ocean alkalinity enhancement on multi-centennial timescales
- Impacts of water advection and CO ₂ exchange on the carbon dioxide removal potential of ocean alkalinity enhancement
BibTeX
@article{bach2026lethal,
title = {{Lethal by Design? Resolving Differences Between Experimental and Real‐World Alkalinity Perturbations in Ocean Alkalinity Enhancement}},
author = {Lennart T. Bach and Michael Dominik Tyka and Bin Wang and Katja Fennel},
journal = {Journal of Geophysical Research Oceans},
year = {2026},
month = aug,
doi = {10.1029/2025jc023598},
url = {https://doi.org/10.1029/2025jc023598},
note = {CC BY-NC},
}
RIS
TY - JOUR
TI - Lethal by Design? Resolving Differences Between Experimental and Real‐World Alkalinity Perturbations in Ocean Alkalinity Enhancement
AU - Lennart T. Bach
AU - Michael Dominik Tyka
AU - Bin Wang
AU - Katja Fennel
PY - 2026
DA - 2026/08/01
JO - Journal of Geophysical Research Oceans
DO - 10.1029/2025jc023598
UR - https://doi.org/10.1029/2025jc023598
AB - Ocean alkalinity enhancement (OAE) aims to mitigate climate change by increasing the chemical capacity of seawater to store anthropogenic CO 2 . OAE can be implemented through multiple pathways, each of which intentionally modifies marine carbonate chemistry through increases in total alkalinity (TA). Experimental research has only recently begun to assess how such TA perturbations (ΔTA) and associated carbonate chemistry changes affect ocean ecosystems. Meaningful assessments need context on how ΔTA‐induced by different OAE pathways would evolve over time and in magnitude. Here, we use a dilution equation, a regional model, and a global model to explore how marine organisms would be exposed to ΔTA under realistic constraints. We find that a more extreme ΔTA of>1,000 μmol kg −1 , a perturbation common in OAE experiments, only occurs for minutes in a minuscule fraction of the OAE‐perturbed seawater volume. In contrast, ΔTA between 1 and 100 μmol kg −1 is a ubiquitous perturbation range for OAE under real‐world constraints, yet are not commonly in focus of environmental OAE assessments. These results suggest that there is a disconnect between real‐world ΔTA that can plausibly be invoked by OAE and the experimental ΔTA range frequently used in the environmental OAE assessment. While “unrealistic” ΔTA can provide mechanistic insights into an organism or ecosystem response to carbonate chemistry changes, they can also cause overestimation of OAE effects, if the unrealistic ΔTA is not contextualized appropriately. Our results can be used to improve the contextualization of OAE studies, thereby making the interpretation of ΔTA effects on the environment more robust.
SN - 2169-9275
SN - 2169-9291
ER -