Continental shelf carbon dioxide (CO2) increase lagged behind atmospheric CO2 rise on the global average (Laruelle et al. 2018). Particularly, the U.S. East Coast shelf suggested to especially exemplifies this pattern (Xu et al. 2020), making this region less vulnerable to ocean acidification (Ekstrom et al. 2015). However, using observations and a reconstructed pCO2 product, we found evidence of rapid coastal partial pressure of CO2 (pCO2) increases along the Gulf Stream-adjacent continental shelf from 2002-2021. Our results showed that the sea surface pCO2 in the Gulf Stream-adjacent South Atlantic Bight (SAB) shelf increased 63% faster than the atmospheric CO2 from 2002-2021. This rapid increase is primarily due to rapid coastal warming and reduced buffer capacity driven by the weakening of the Gulf Stream. Statistically significant relationships between pCO2, sea surface temperature, and Gulf Stream dynamics demonstrated the crucial role of this western boundary current in driving regional acidification trends. Additionally, we developed multiple linear regression models to reconstruct past pCO2 and constrain future projections, revealing that the SAB shelf has experienced faster acidification than the Mid-Atlantic Bight (MAB) shelf that away from the Gulf Stream since the 1990s. The Gulf Stream's relative vorticity could serve as a constraint for future pCO2 elocution projection in CMIP6 on the US East Coast, reducing the projected uncertainty by more than 32%. Our findings suggest that Gulf Stream-adjacent areas may be more vulnerable to accelerated ocean acidification, with potential implications for other Western Boundary Current regions globally, highlighting the need for targeted mitigation strategies in these sensitive ecosystems.

Gulf Stream, ocean acidification, pCO2