Air-sea carbon dynamics in Baffin Bay: 2011-2021

• Main Author: Nickoloff, Gina Mary
• Other Authors: Else, Brent, Marshall, Shawn, Kimura-Hara, Susana
• Format: Master Thesis
• Language: English
• Published: Graduate Studies 2023
• Subjects: air-sea CO2 fluxes; Arctic; Baffin Bay; pCO2; Geography; Oceanography; Biogeochemistry; Baffin; Climate change; Nares strait
• Online Access: https://hdl.handle.net/1880/116897; https://doi.org/10.11575/PRISM/41739

Arctic waters play a disproportionately large role in oceanic CO2 uptake, but are most vulnerable to impacts of climate change. Due to the Arctic’s limited accessibility and remote nature, oceanic CO2 data is sparse to the extent that observation-based estimates of air-sea CO2 flux have only been derived for certain regions, leaving considerable uncertainty in the contribution of Arctic seas to global carbon budgets. Comprehensive description of surface-ocean CO2 dynamics in poorly-studied Arctic regions is needed to constrain Arctic and global carbon cycles, and to anticipate and document future change. In this thesis I provide such a novel description for the Baffin Bay region by examining the spatial and temporal distributions of surface-ocean partial pressure of CO2 (pCO2) while identifying its driving physical and biogeochemical controls, and by quantifying air-sea CO2 fluxes over the region during the open-water season. Utilising an extensive continuous underway ship-based pCO2 dataset accumulated over the last decade, 2011 to 2021, I report surface-ocean pCO2 over Baffin Bay (which in this definition includes Nares Strait and the Northwater Polynya) from June to October. Baffin Bay was highly favourable to uptake of atmospheric CO2 (70 to 130 μatm below saturation, depending on the year), but had substantial regional variability in pCO2 due to hydrography and ocean currents. Over the open-water season pCO2 exhibited a temporal pattern, increasing June to October but remaining undersaturated. Through comprehensive evaluation of Baffin Bay air-sea CO2 fluxes I show that it is a notably strong uptake region, even when compared to other North American Arctic regions. Baffin Bay had an average open-water-season flux of -7.3 mmol CO2 m-2 day1, which corresponds to an estimated carbon uptake of 11.9 Tg C year-1. Ice coverage in some regions served as a barrier to uptake, particularly in the northern portions of the study region. In the future, Baffin Bay is expected to remain a strong uptake region, with ...