A real world experiment in Southampton, New York, has provided the first field evidence that crushed olivine a green silicate mineral found in Earth’s mantle may help oceans absorb carbon dioxide, though researchers say it is still too early to judge its long-term safety or climate impact.
In 2022, scientists spread around 650 tons of crushed olivine across a section of beach as part of a controlled coastal trial. The mineral was later carried offshore by waves, where it began interacting with seawater and atmospheric CO₂. The goal was to test whether this natural chemical reaction, known as enhanced rock weathering, could be accelerated in coastal environments to help reduce carbon levels in the atmosphere.
Olivine reacts with carbon dioxide in seawater and converts it into stable bicarbonate ions, a form of carbon that can remain stored in the ocean for thousands of years. In theory, this process could make coastal zones and shallow seas important tools in large-scale carbon removal strategies.
The Southampton trial is the first of its kind conducted outside laboratory conditions. Researchers monitored the seabed for one year, tracking marine life and chemical changes before and after the mineral was added.
According to the study, the benthic ecosystem the community of organisms living on and within the seafloor sediment showed initial disturbance but recovered relatively quickly. Species abundance and diversity returned to levels similar to control sites within about two months. Some shifts were observed in certain small invertebrates, but similar changes also occurred in areas where only regular beach sand was added, suggesting that routine beach nourishment may have been a larger factor than the mineral itself.
Importantly, chemical analysis of marine organisms found no significant accumulation of potentially concerning trace metals such as nickel, chromium, cobalt, or manganese over the one-year period. These elements are naturally present in olivine and have been a major concern in environmental risk assessments.
Despite these encouraging early results, scientists and environmental groups stress that the findings are not yet definitive. Critics argue that the experiment’s scale, duration, and dilution effects from surrounding sand may have limited exposure, making it difficult to fully assess long-term ecological risks.
Researchers also acknowledge that scaling up olivine deployment would raise additional questions, including emissions from mining and grinding the mineral, transport impacts, and the ability to accurately measure how much carbon is actually being removed from the atmosphere and stored in the ocean system.
A larger follow-up trial off the coast of North Carolina is currently underway, where thousands of tons of olivine have been deployed to better understand long-term ecological and chemical effects under more extensive conditions.
For now, the Southampton experiment suggests that olivine-based carbon removal is not immediately harmful at small scales and may hold potential as a climate mitigation tool. However, scientists emphasize that one year coastal results are only the beginning of a much longer evaluation process before such approaches could be considered for global application.