Can Ocean Alkalinity Enhancement Really Save Marine Life?

The Promise of OAE

Ocean Alkalinity Enhancement (OAE) is a method designed to counteract ocean acidification and support marine life, particularly marine calcifiers—creatures that build shells or skeletons from calcium carbonate.

The Challenge

Recent studies reveal that OAE may not be as effective as initially hoped. Researchers examined 27 types of marine calcifiers, which are struggling due to increasing ocean acidity.

Key Findings:

• Significant decline in calcification for species like gastropods and pteropods since pre-industrial times.
• Threshold responders (other species) show only a small decline.

The Role of Alkalinity

Adding alkalinity to the ocean helps, but large amounts are needed to restore calcification rates fully.

• 50 μmol kg⁻¹ of alkalinity only partially restores calcification rates.
• Most sensitive species benefit the most.
• Full restoration of pre-industrial rates requires much larger amounts, especially when accounting for CO₂ equilibration with the atmosphere.

Climate vs. Ocean Goals

While OAE can help marine life, it may not align perfectly with climate goals.

• Processes that enhance OAE's CO₂ removal can reduce its ability to mitigate ocean acidification.
• This creates challenges for ocean management and climate policy.

Conclusion

OAE has potential benefits, but it is not a straightforward solution.

• Substantial alkalinity is needed for full restoration.
• Effectiveness in mitigating ocean acidification may conflict with climate goals.

Therefore, OAE must be approached critically, with careful consideration of its limitations.