Henson Henry C, Sejr Mikael, Meire Lorenz, Sørensen Lise Lotte, Winding Mie H S, Holding Johnna M
Department of Ecoscience Aarhus University Midtjylland Denmark.
Arctic Research Centre Aarhus University Aarhus Denmark.
J Geophys Res Biogeosci. 2024 Dec;129(12):e2024JG008246. doi: 10.1029/2024JG008246. Epub 2024 Nov 27.
The oceans play a pivotal role in mitigating climate change by sequestering approximately 25% of annually emitted carbon dioxide (CO). High-latitude oceans, especially the Arctic continental shelves, emerge as crucial CO 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 CO 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 CO sinks in summer. Geographical variation in CO and air-sea exchange was linked intricately to freshwater export from the Greenland ice sheet and levels of primary production in these ecosystems. Air-sea exchange of CO ranged from 0.23 to -64 mmol m day. However, we found that flux estimation faces substantial uncertainties (up to 672%) due to wind product averaging and gas exchange formula selection. Upscaling only heightens this uncertainty leading to wide ranging estimates of Greenland coastal CO uptake between -16 and -26 Tg C year (This study, Dai et al., 2022, https://doi.org/10.1146/annurev-earth-032320-090746; Laruelle et al., 2014, https://doi.org/10.1002/2014gb004832). Obtaining a reliable assessment of air-sea CO exchange necessitates data collection across seasons, and, even more so, refinement of the gas transfer velocity estimations in the Arctic coastal zone.
海洋通过吸收每年约25%的二氧化碳排放，在缓解气候变化方面发挥着关键作用。高纬度海洋，尤其是北极大陆架，因其寒冷、低盐和高生产力的生态系统，成为重要的二氧化碳汇。然而，这些异质区域仍未得到充分了解，阻碍了对其碳动态的准确评估。本研究调查了格陵兰岛沿海海洋冰盖融化高峰期二氧化碳水平的变化，并估计了6个纬度范围内的海气交换速率。格陵兰岛的东海岸和西海岸呈现出具有独特控制因素的不同区域。不过，两个海岸在夏季均为二氧化碳汇。二氧化碳和海气交换的地理变化与格陵兰岛冰盖的淡水输出以及这些生态系统中的初级生产力水平密切相关。海气二氧化碳交换范围为0.23至 -64 mmol m² day⁻¹。然而，我们发现由于风产品平均和气体交换公式选择，通量估计面临很大的不确定性（高达672%）。向上扩展只会加剧这种不确定性，导致对格陵兰岛沿海二氧化碳吸收量的估计范围很广，在 -16至 -26 Tg C year⁻¹之间（本研究，Dai等人，2022年，https://doi.org/10.1146/annurev-earth-032320-090746；Laruelle等人，2014年，https://doi.org/10.1002/2014gb004832）。要获得可靠的海气二氧化碳交换评估，需要跨季节收集数据，更重要的是，需要改进北极沿海地区的气体传输速度估计。
