Ocean acidification is a significant issue caused by increased atmospheric CO₂, which is absorbed by the ocean, altering its chemistry. The saturation state of calcium carbonate in the ocean has decreased, leading to potential impacts on marine life. The saturation horizon for both aragonite and calcite has moved closer to the surface due to anthropogenic CO₂. This shift affects organisms that rely on calcium carbonate for their shells and skeletons, such as pteropods, mussels, oysters, and coccolithophores. Experiments show that increased CO₂ levels reduce calcification rates and can cause shell dissolution in some species. Coastal upwelling and other natural processes may accelerate ocean acidification in coastal waters. The effects of ocean acidification on food webs and biogeochemical cycles are not fully understood, but there are concerns about the potential impacts on marine ecosystems. Research indicates that changes in species composition and abundances could occur, which may affect food webs and biogeochemical cycles. Baseline data on calcium carbonate saturation states in coastal regions are lacking, making it difficult to predict the full extent of ocean acidification's impacts. Overall, ocean acidification is a complex issue with far-reaching consequences for marine ecosystems.Ocean acidification is a significant issue caused by increased atmospheric CO₂, which is absorbed by the ocean, altering its chemistry. The saturation state of calcium carbonate in the ocean has decreased, leading to potential impacts on marine life. The saturation horizon for both aragonite and calcite has moved closer to the surface due to anthropogenic CO₂. This shift affects organisms that rely on calcium carbonate for their shells and skeletons, such as pteropods, mussels, oysters, and coccolithophores. Experiments show that increased CO₂ levels reduce calcification rates and can cause shell dissolution in some species. Coastal upwelling and other natural processes may accelerate ocean acidification in coastal waters. The effects of ocean acidification on food webs and biogeochemical cycles are not fully understood, but there are concerns about the potential impacts on marine ecosystems. Research indicates that changes in species composition and abundances could occur, which may affect food webs and biogeochemical cycles. Baseline data on calcium carbonate saturation states in coastal regions are lacking, making it difficult to predict the full extent of ocean acidification's impacts. Overall, ocean acidification is a complex issue with far-reaching consequences for marine ecosystems.