Oceanic uptake of anthropogenic CO2 emissions induced global seawater pH decrease by 0.1 since the Industrial Revolution by altering ocean chemistry with the reduction of carbonate ion concentrations and the saturation states of aragonite. Massive tropical corals are ideal palaeoceanographic archives providing high-resolution records of the most recent few hundred years and offer a valuable extension to instrumental measurements. The South Pacific Convergence Zone (SPCZ), the largest persistent precipitation band in the Southern Hemisphere with...