This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: When scientists discovered that increasing the ocean's natural alkalinity could enhance seawater's capacity to absorb and store carbon dioxide (CO₂), the idea quickly gained attention as a potential geoengineering solution to climate change. Early visions suggested it could remove gigatonnes of CO₂ from the atmosphere each year.
But the reality is far more complex. In a new article published in Nature Reviews Earth & Environment, scientists urge that the focus of ocean alkalinity enhancement (OAE) be shifted from a science fiction–flavored geoengineering intervention to a practical, flexible tool for local CO2 management. "We argue that integrating small-scale OAE into diverse local contexts could deliver the achievable carbon mitigation goals defined by individual governments and communities," said lead author Lennart Bach, an associate professor and biogeochemical oceanographer at the University of Tasmania's Institute for Marine and Antarctic Studies (IMAS).
"For example, a city council might realize that its emissions from domestic wastewater could be mitigated through alkalinity from silicates. Or a regional wind farm might not need to be shut off during excess wind if the energy is used to increase seawater alkalinity electrochemically. "Upscaling could be achieved across these local areas, but only if those pathways are environmentally responsible, demonstrably carbon negative and earn public trust," Bach said.
Ocean alkalinity enhancement reduces acidity in seawater and converts CO₂ into mainly inert bicarbonate ions. This chemical reaction enables bicarbonate ions to be stored en masse in the ocean for millennia. "The chemistry is scientifically understood and predictable, and the available evidence suggests storing carbon as bicarbonate would not harm marine life," IMAS researcher and co-author Dr.
"In fact, natural alkalinity is transported by rivers into the sea and has been regulating the climate naturally throughout Earth's history. Without it, our climate would be utterly inhospitable to human life." However, while OAE is versatile and can be adjusted to a range of ocean environments, Britton said OAE alters the environment in other ways in addition to simply increasing alkalinity. "Depending on the method of alkalinity addition, OAE can increase turbidity and introduce additional elements such as trace metals alongside the alkalinity," he said.
"Understanding how these and other perturbations from OAE interact with local marine life is critical to understanding where small-scale OAE can be safely implemented and whether the environmental risks outweigh the benefits." "In theory, the ocean has more than enough 'space' to safely sequester all human emissions. We would only need to increase the mean alkalinity of the ocean by about 2% to store all of the approximately 2,660 billion tonnes of CO₂ released since the Industrial Revolution," said IMAS researcher and co-author Dr. "The problem is that it's not obvious how we could evenly distribute that much alkalinity across the global ocean and ensure it is in contact with the atmosphere long enough to absorb its full potential of CO₂.
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