In the summer of 2022, a previously unknown precipitating sediment was discovered in the eastern Mediterranean, which occurred in large quantities. This was the mineral aragonite, which can form when water temperatures rise. When the mineral forms, the absorption capacity of CO₂ in the water is reduced so that CO₂ increasingly outgasses into the atmosphere. The rising water temperatures can therefore mean that the sea is no longer a CO₂ sink, but becomes a CO₂ source.

Source:

Bialik, O.M., Sisma-Ventura, G., Vogt-Vincent, N. et al. Role of oceanic abiotic carbonate precipitation in future atmospheric CO₂ regulation. Sci Rep 12, 15970 (2022). https://doi. org/10.1038/s41598-022-20446-7