Global trends in ocean fronts: impacts on air-sea CO2 flux and chlorophyll concentrations

Ocean fronts are dynamic features that play a critical role in regulating marine ecosystems and influencing global carbon cycles. These regions, characterized by strong horizontal gradients in temperature, salinity, and other properties, enhance vertical mixing and advection, driving increased nutrient supply that supports elevated primary production. Despite their importance, the impacts of changing ocean fronts on the budget and trends of ocean CO₂ uptake remain insufficiently understood. In this study, we perform a comprehensive global analysis of ocean fronts using 20 years of satellite observations (2003–2023), identifying key regions of intense frontal activity and areas undergoing rapid changes in frontal dynamics. Our results show that nearly 50% of global ocean CO₂ uptake occurs in these key frontal areas, underscoring their disproportionate role in the ocean’s carbon sink. Furthermore, we observe that trends in sea surface chlorophyll concentration—a proxy for primary production—and ocean CO₂ uptake are strongly correlated with local changes in frontal activity. Our findings provide critical insights into the role of ocean fronts as modulators of global biogeochemical processes and air-sea CO₂ exchanges. By linking ocean fronts to changes in primary production and air-sea CO₂ exchange, this study contributes to a more detailed understanding of how changing ocean dynamics may influence carbon cycles under future climate scenarios.