CO2 ice formations discovered on Indian Ocean floor near Mayotte

Ifremer announced this scientific finding on June 12, attributing it to the appearance of the Fani Maore volcano. These unusual formations, resembling "large agglomerated snowmen," are located at a depth of 1,200 meters, where the water temperature is 4°C. Cécile Cathalot, a marine geochemistry researcher at Ifremer and lead author of a study published on Friday, stated that this is the first observation of CO2 hydrates on the ocean floor. Ifremer suggests that the appearance of these magmatic liquid CO2 sources in the Horseshoe area is likely linked to the seismic-volcanic crisis affecting Mayotte, which includes the formation of the new Fani Maoré volcano discovered in 2019.

This activity may have destabilized the volcanic structure of the Horseshoe, which predates the Fani Maore eruption. The initial discovery of these formations was made in 2021 by an international team of researchers, with a subsequent campaign in August 2025 revisiting the site, which appears stable over the preceding four years. This area serves as a natural laboratory, offering the opportunity to study natural processes, ecosystem responses, and the long-term effects of excess CO2 exposure in the underwater environment.

The discovery could also aid in studying CO2 sequestration pathways through gas hydrate formation, parti