Coastal ocean CO2 uptake and climate feedback variability


The coastal ocean is a dynamic environment connecting the land and ocean as the two primary sinks in the global carbon cycle. Quantifying coastal carbon fluxes is thus relevant for understanding the controls of the Earth´s climate and addressing impacts of climate change mitigation efforts. Yet, ongoing global carbon budgeting initiatives highlight the need for further investigation of the land-ocean transition zone to constrain uncertainties in carbon burial, transport and air-sea gas exchange. I will present the global ocean-biogeochemistry model ICON-Coast, which seamlessly integrates the coastal ocean in marine carbon cycle modeling. Results from hindcast simulations provide insights into the main drivers of the increasing CO2 uptake of the coastal ocean. I will show that biological responses to climate-induced circulation changes and riverine nutrient inputs are key to the enhanced coastal uptake, and lead to a net CO2 flux density that is higher than in the open ocean. However, coastal climate feedback mechanisms, such as the loss of Arctic permafrost organic carbon due to increasing coastal erosion, regionally modulate the air-sea CO2 exchange and its interannual variability. These results emphasize the importance of understanding region-specific dynamics of the marine carbon cycle to comprehend and predict drivers and impacts of global climate change.


via Zoom