As the level of the CO2 concentration continuously rises in the earth atmosphere so is rising the concentration of intact carbonic acid H2CO3 (CA ) in the earth seas and in our atmosphere because of the reaction CO2 + H2O = H2CO3 .We determined with high precision the temperature dependence of the pKa of carbonic acid in water, pKa(T) = - 373.604 + 16500/T + 56.478 lnT, making it a moderately strong carboxylic acid in water, stronger than what was considered before. We demonstrate the ability of intact carbonic acid to act in similar way to stable carboxylic acids of comparable acid strength and directly protonate moderate bases in various liquid environments and argue that this chemical reactivity of intact CA has not been fully appreciated. We also argue that CA is likely to be long-lived in the earth atmosphere when adsorbed on solid surfaces such as ice particles. We demonstrate that the decomposition reaction of CA to form water and CO2 is environment- sensitive, CA reaching in our measurements a full one-minute lifetime in some non-aqueous partially aprotic solutions. The activation energy for the spontaneous decomposition of CA to water and CO2 is high, about 10 kcal/mol in water so CA is likely to become considerably more stable at the low air temperatures prevailing in the earth atmosphere and near the surface of the oceans in the northern and southern hemispheres during winter times when water temperatures there drop to below 0oC. This makes intact CA a potentially important factor in marine biology and in chemical processes occurring in the earth atmospheric, probably having negative effects on our environment due to the CO2 crisis.

Rising concentrations of intact carbonic acid in the earth seas and atmosphere due to rising levels of atmospheric CO2 are likely to have considerable still unappreciated environmental effects

ACS Fall 2021

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