Analyzing Patterns of Ocean Acidification in the Atlantic Interior Ocean and Associated Environmental Vulnerability with CMIP6 Models

• Main Author: Wani, Rucha
• Format: Thesis
• Language: unknown
• Published: University of Delaware 2021
• Subjects: Acidification; Atlantic basin; Carbon; Southern Ocean; Ocean acidification
• Online Access: https://udspace.udel.edu/handle/19716/31055

Increased uptake of anthropogenic carbon emissions during the formation of deep-water masses in polar regions has resulted in deep-sea acidification. Additionally, remineralization of organic carbon in older water masses naturally increases acidity. Observation and management of acidification can be difficult when there are multiple sources contributing to the acidification signal. The purpose of this study is to discern the sources of acidification at a local and regional scale. Patterns of acidification were investigated by analyzing trends in carbon-system variables across longitudinal transects and horizontal cross-sections in the Atlantic basin. In-situ measurements from the Global Ocean Data Program (GLODAPv2) and predictions from the Geophysical Fluid Dynamics Laboratory’s (GFDL) Earth System Model 4.1 and Climate Model 4.0 revealed high chlorofluorocarbon concentrations below the thermocline, along the western boundary of the Atlantic basin. Congruous trends in other carbon system variables demonstrate an acidification signal that has already exceeded natural variability and poses an increasing potential threat to deep pelagic and benthic communities along the spatial extent of these acidic water masses. Analysis expanded to the entire Atlantic basin indicates large scale acidification patterns within and below the permanent thermocline. Sources of acidification in the North Polar Atlantic as well as both gyres are mainly from anthropogenic changes in ventilated water, whereas acidification in the Southern Ocean is caused by the slumping of older water masses with higher natural acidification via remineralization of organic carbon. While these results confirm forthcoming acidification of the deep ocean, they also elucidate the complexity of acidification along certain regional boundaries that will experience heightened ecosystem vulnerability than other regions. Wei-Jun Cai Marine Science