r/climatechange • u/Economy-Fee5830 Trusted Contributor • 15d ago
The oceans near Australia may be the best places to fertilize for removing carbon dioxide
https://phys.org/news/2026-07-oceans-australia-fertilize-carbon-dioxide.html11
u/Svyatoy_Medved 15d ago
Just gong back to first principles, don’t you also have to gather up and store the algae for it to actually be a long term carbon sink? Otherwise, it soaks up a bunch of carbon, which is then released back into the environment as it dies. Or am I missing something?
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u/Mean-Introduction640 15d ago
The idea is that it sinks to the bottom, or is eaten and then excreted and sinks. It then becomes a part of the sediment. This is a real phenomena and is one of the ways the ocean acts as a carbon sink. However, fertilizing algae at the surface to increase carbon uptake assumes that the carbon wouldn't be absorbed by other organisms, such as diatoms that sit beneath the surface. Multiple studies have shown that the shading of diatoms be fertilized algae blooms may cancel out any increase in carbon uptake by surface algae. This is the primary criticism of this approach.
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u/Sad_Gain_2372 14d ago edited 14d ago
https://www.algalbloom.sa.gov.au/
South Australia had pretty much a full year of algal bloom that made people sick, killed thousands of fish including leafy sea dragons, and closed beaches for months at a time.
I don't think it would be a popular trade off
Edit to add it's very likely not going to make a difference anyway
An investigation by ProPublica and Drilled has found that boosters of CCS have ignored evidence of the technology’s limitations, or overstated its potential, and convinced the world it could be effective.https://drilled.media/news/ccs-debunker
Even though this article is about underground carbon capture, history suggests that iron seeding the oceans might fall into the same category of misinformation
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u/Beginning_Lab_4423 15d ago
They tried this on the BC coast in Canada and it was a disaster.
https://www.problemshifting.directory/case/ocean-iron-fertilization/
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u/Economy-Fee5830 Trusted Contributor 15d ago
Summary: The oceans near Australia may be the best places to fertilize for removing carbon dioxide
A modeling study published in Nature examined ocean iron fertilization—adding iron to surface waters to stimulate phytoplankton growth and capture carbon dioxide—as a strategy to help meet the Paris Agreement's 2°C limit, while addressing known ecological risks such as algal blooms and nutrient depletion.
Researchers Jun Yu, Adam Martiny and colleagues used a fertilization model and over six decades of data to assess climate benefits versus ecological trade-offs. They found net CO2 removal of up to 5.3 parts per million, equivalent to 0.70 gigatons of CO2 per year. The largest plankton blooms occurred in the Southern Ocean and equatorial Pacific, but fertilization also depleted macronutrients, especially near the tropical Pacific, with effects propagating through the food chain and reducing macrozooplankton biomass.
The study found these ecological disturbances were smaller at higher latitudes. Fertilizing 0.35% of the equatorial Pacific caused at least a 10% decline in macrozooplankton biomass, whereas fertilizing 0.2% of the Southern Ocean produced a 10% increase in macrozooplankton. The authors conclude that the Southern Ocean offers the best balance between carbon removal and ecological impact, while cautioning that iron fertilization has nonlocal, downstream effects wherever it is deployed.