Ocean acidification is the ongoing decrease in the pH of the Earth’s oceans (increase of acid ty)

A pH less than 7 is acidic, and a pH greater than 7 is basic/alkaline. (pH means Potential of Hydrogen)
Currently, Oceans has around pH of 8.0 i.e. basic

Primary and Major - Uptake of carbon dioxide (CO2) from the atmosphere.
Acid Rains
Eutrophication - plankton blooms, and when these blooms collapse and sink to the sea bed and the subsequent respiration of bacteria decomposing the algae leads to a decrease in sea water oxygen and an increase in CO2

Carbonic acid further splits into H ions and BiCarbonate ions which further splits into H ions and Carbonate ions

Increasing acidity reduces metabolic rates and immune responses in some organisms.
Effects calcifying ability of marine organisms

If Under saturated with carbonate ions - causes shells of dead marine organisms to dissolve - calcification difficult
If Over saturated with Carbonate ions - do not readily dissolve - calcification easy
Generally, Surface waters over saturated and deep sea waters undersaturated
Ocean acidification results in increased availability of bicarbonate ions (HCo3-1) and decrease of carbonate ions (Co3-2) which means under saturation of carbonate ions which means reduces the calcifying ability of marine organisms such as hard tropical corals, cold water corals, molluscs, crustaceans, sea urchins, certain types of plankton, lobsters,

Acidification of oceans causes the saturation horizon line come closer to the surface

Usually, deep cold ocean waters are under saturated with carbonate ions and surface waters are over saturated with carbonate ions
Lysocline or Saturation Horizons: Imaginary line in ocean depths below which calcium carbonate minerals undergo dissolution and above which it will not dissolve

Commercial fisheries are threatened because acidification harms calcifying organisms
Impact of Ocean Acidification on Cloud Formation

Oceans generally release Sulphur into atmosphere as dimethylsulfide (DMS) which is produced by phytoplan kton
DMS which mixes with aerosols and microscopic airborne particles helps in seeding of clouds
Acidification leads to reduction in release of DMS which in turn reduces the formation of clouds

Ocean Acidification