Abstract
The oceans play a pivotal role in mitigating climate change by
sequestering approximately 25% of annually emitted anthropogenic carbon
dioxide (CO2). High-latitude oceans, especially the Arctic continental
shelves, emerge as crucial CO2 sinks due to their cold, low saline, and
highly productive ecosystems. However, these heterogeneous regions
remain inadequately understood, hindering accurate assessments of their
carbon dynamics. This study investigates variation in pCO2 levels during
peak ice sheet melt, in the Greenland coastal ocean and estimates rates
of air-sea exchange across 6° of latitude. The East and West coast of
Greenland displayed distinct regions with unique controlling factors.
Though, both coasts represent CO2 sinks in summer. Geographical
variation in pCO2 and air-sea exchange was linked intricately to
freshwater export from the Greenland ice sheet and levels of primary
production in these ecosystems. CO2 uptake ranged from 0.17 to -38 mmol
m-2 day-1. However, we found that flux estimation faces substantial
uncertainties (up to 770%) due to wind product averaging and gas
exchange formula selection. Despite these considerations, we report a
first order estimate that Greenland coastal ocean takes up -9.5 ± 9.0 Tg
C year-1, corresponding to nearly 4% of global coastal CO2 uptake.
Obtaining a reliable assessment of air-sea CO2 exchange necessitates
data collection across seasons, and, even more so, refinement of the gas
transfer velocity estimations in the Arctic coastal zone.