The Pacific-Arctic Region (PAR) is highly vulnerable to ocean acidification (OA)due to its low buffer capacity, carbonate concentration, and the regionally-amplifiedeffects of climate change. Although it experiences the highest rates of OA globally, the existing literature lacks observation-based surface decadal OA rates forthe PAR, primarily due to large data gaps. To address these limitations, we aggregated open-source carbonate datasets and established spatially-dependent relationships to predict surface total alkalinity (TA) using salinity and temperature (R2=0.93, MAE = 23 µmol kg−1). We then applied these relationships to gridded sea surface salinity and temperature products to obtain monthly surface TA fields. The TA fields were coupled with the MPI-SOM-FFN surface pCO2 dataset (doi: 10.7289/v5z899n6) to obtain monthly 1°x 1° surface pH, ΩAr, and dissolved inorganic carbon fields from 1993-2021 for the entire PAR, yielding the first gapless gridded Arctic carbonate system dataset to date. This dataset indicated that the Southern PAR acidified at rates comparable to the global average, predominantly due to the absorption of anthropogenic CO2. In contrast, the Bering Sea shelf exhibited basification, likely a result of increased primary productivity. The Northern PAR exhibited acidification rates 2-4x greater than the global rate due to reduced TA linked to sea ice melt. Our findings suggest that continued warming will likely exacerbate surface acidification in regions experiencing a shift from yearround multi-year ice cover to a seasonal ice pack. While local processes such as primary productivity can temporarily counteract OA, whether they can compensate for rising anthropogenic CO2 levels is unclear. This highlights the complexity of predicting future ocean acidification trends and underscores the importance of advanced models that integrate both climatic and biological factors, enabling accurate forecasts of impacts on marine ecosystems in these highly sensitive regions
Careo T. V., 2024. A spatiotemporal analysis of ocean acidification in the Pacific-Arctic region. MSc Thesis, University of Rhode Island, 83 p. Thesis (restricted access).
