Calculate ocean pH changes and carbonate chemistry from atmospheric CO2 concentrations, temperature, and salinity to understand ocean acidification impacts.
Ocean pH
--
Dissolved CO2
--
Bicarbonate (HCO3⁻)
--
Carbonate (CO3²⁻)
--
Aragonite Saturation (Ωar)
--
Dissolved Inorganic Carbon
--
Ocean acidification refers to the ongoing decrease in ocean pH caused by absorption of atmospheric CO2. As CO2 dissolves in seawater, it forms carbonic acid, lowering the pH from pre-industrial levels of 8.2 to current levels around 8.1.
Ocean surface pH has dropped from 8.2 to 8.1 since pre-industrial times, representing a 25% increase in hydrogen ion concentration. This may seem small, but pH is logarithmic, making this a significant change.
Aragonite saturation (Ωar) measures how easily marine organisms can build calcium carbonate shells and skeletons. When Ωar drops below 1, shells and coral skeletons begin to dissolve, threatening marine ecosystems.
Warmer water holds less CO2 but chemical reactions proceed faster, affecting the carbonate system. Colder water absorbs more CO2, potentially experiencing greater acidification effects in polar regions.
The main carbonate species are dissolved CO2, bicarbonate ions (HCO3⁻), and carbonate ions (CO3²⁻). As CO2 increases, more bicarbonate forms while carbonate decreases, affecting shell-building organisms.
Salinity affects the chemical equilibrium constants used in carbonate system calculations. Higher salinity changes the activity coefficients and solubility of carbonate minerals, influencing pH and saturation states.
Deeper waters experience higher pressure, which affects CO2 solubility and carbonate mineral solubility. Deep waters are often naturally more acidic and closer to undersaturation for carbonate minerals.
Climate models project atmospheric CO2 could reach 500-1000 ppm by 2100 depending on emissions scenarios. This would further lower ocean pH to potentially 7.7-7.8, representing a 150% increase in acidity from pre-industrial levels.