The Net Ecosystem Carbon Balance (NECB) at catchment scales in the Arctic

Efrén López-Blanco ^1,2* Maria Väisänen ³ Elodie Salmon ⁴ Cheristy P. Jones ⁵ Niels M. Schmidt ¹ Hannu Marttila ³ Annalea Lohila ⁶ Sari Juutinen ⁶ Johan Scheller ⁷ Torben R. Christensen ^1,3

• ¹ Department of Ecoscience and Arctic Research Centre, Aarhus University, Aarhus, Denmark
• ² Department of Environment and Minerals, Greenland Institute of Natural Resources, Nuuk, Greenland
• ³ Water, Energy and Environmental Engineering Research Unit, University of Oulu, Oulu, Northern Ostrobothnia, Finland
• ⁴ Laboratoire des Sciences du Climat et de l’Environnement, CEA-CNRS-UVSQ, Gif-sur-Yvette, France
• ⁵ Department of Earth Sciences, Earth Systems Research Center, Institute for the Study of Earth, Oceans, and Space, University of New Hampshire, Durham, New Hampshire, United States
• ⁶ Climate System Research, Finnish Meteorological Institute, Helsinki, Uusimaa, Finland
• ⁷ Danish Meteorological Institute (DMI), Copenhagen, Denmark

The Net Ecosystem Carbon Balance (NECB) is a crucial metric for understanding integrated carbon dynamics in Arctic and boreal regions, which are vital to the global carbon cycle. These areas are associated with significant uncertainties and rapid climate change, potentially leading to unpredictable alterations in carbon dynamics. This mini-review examines key components of NECB, including carbon sequestration, methane emissions, lateral carbon transport, herbivore interactions, and disturbances, while integrating insights from recent permafrost region greenhouse gas budget syntheses.We emphasize the need for a holistic approach to quantify the NECB, incorporating all components and their uncertainties. The review highlights recent methodological advances in flux measurements, including improvements in eddy covariance and automatic chamber techniques, as well as progress in modeling approaches and data assimilation. Key research priorities are identified, such as improving the representation of inland waters in process-based models, expanding monitoring networks, and enhancing integration of long-term field observations with modeling approaches. These efforts are essential for accurately quantifying current and future greenhouse gas budgets in rapidly changing northern landscapes, ultimately informing more effective climate change mitigation strategies and ecosystem management practices. The review aligns with the goals of the Arctic Monitoring and Assessment Program (AMAP) and Conservation of Arctic Flora and Fauna (CAFF), providing important insights for policymakers, researchers, and stakeholders working to understand and protect these sensitive ecosystems.