Variability and trends in surface seawater pCO₂ and CO₂ flux in the Pacific Ocean

Variability and change in the ocean sink of anthropogenic carbon dioxide (CO 2 ) have implications for future climate and ocean acidification. Measurements of surface seawater CO 2 partial pressure ( p CO 2 ) and wind speed from moored platforms are used to calculate high‐resolution CO 2 flux time series. Here we use the moored CO 2 fluxes to examine variability and its drivers over a range of time scales at four locations in the Pacific Ocean. There are significant surface seawater p CO 2 , salinity, and wind speed trends in the North Pacific subtropical gyre, especially during winter and spring, which reduce CO 2 uptake over the 10 year record of this study. Starting in late 2013, elevated seawater p CO 2 values driven by warm anomalies cause this region to be a net annual CO 2 source for the first time in the observational record, demonstrating how climate forcing can influence the timing of an ocean region shift from CO 2 sink to source.