Imprints of Atlantic Multidecadal Oscillation on pantropical seawater pH inferred from coral δ11B records

Understanding natural variability in seawater pH (pH_sw) is crucial for predicting future ocean acidification. Coral boron isotopes (δ¹¹B) offer an alternative method to extend pH_sw records back centuries, shedding light on how pH_sw varies over time. This study compiles both new and existing coral δ¹¹B records from pantropical oceans to investigate multidecadal pH_sw variability and its connection to climate variability. A notable finding is the pronounced influence of the Atlantic Multidecadal Oscillation (AMO) on pantropical coral δ¹¹B-pH variations. This is primarily interpreted as the effects of AMO-associated climate changes on reef pH_sw, rather than influencing coral physiological processes related to calcifying fluid pH. Key factors like wind speeds and hydrological variability related to Intertropical Convergence Zone (ITCZ) shifts are identified as potential drivers of the AMO's impact on pH_sw. This study thus provides valuable insights into the broader effects of the Atlantic climate on pantropical seawater CO₂ system.