Evaluating Ecosystem Vulnerability to Acidification at Continental Slopes and the mid-Atlantic Ridge in GFDL's CMIP6 Models

Abstract:

Increased uptake of anthropogenic carbon emissions during the formation of deep-water masses in polar regions has resulted in elevated acidification of deep-sea ecosystems. Additionally, warm, and oxygen-depleted western boundary currents carrying water to the polar regions have increased acidity, due to water's enhanced ability to ionize hydrogen in warmer temperatures. The western Atlantic basin likely faces greater environmental vulnerability to acidification than the eastern basin as a result of these combined forcings. The nature of these possible changes was investigated by analyzing trends in carbon-system variables across longitudinal transects in the Northern and Southern Atlantic basin. In-situ measurements from the Global Ocean Data Program (GLODAP) and predictions from the Geophysical Fluid Dynamics Laboratory’s (GFDL) Earth System Model 4.1 and Climate Model 4.0 revealed spatially large subthermal plumes of chlorofluorocarbons along the western boundary of the Atlantic basin. Congruous trends in other carbon system variables, such as increased dissolved inorganic carbon and decreasing pH were observed and are indicative of increasing threats to deep pelagic and benthic communities along the spatial extent of these plumes. While these results confirm forthcoming acidification of the deep ocean, they also elucidate the inconsistent acidification along certain regional boundaries that will experience heightened ecosystem vulnerability than other regions.