Understanding interactions between complex human and natural systems involved in urban carbon cycling is important when balancing the dual goals of urban development to accommodate a growing population, while also achieving urban carbon neutrality. This study develops a systems breakdown accounting method to assess the urban carbon cycle. The method facilitates greater understanding of the complex interactions within and between systems involved in this cycle, in order to identify ways in which humans can adapt their interactions to reduce net greenhouse gas emissions from urban regions. Testing the systems breakdown accounting method in Stockholm County, Sweden, we find that it provides new insights into the carbon interactions with urban green-blue areas in the region. Results show how Stockholm County can reduce its emissions and achieve its goal of local carbon net-neutrality, if the green areas protect its carbon sequestration potential and maintain it to offset projected remaining active emissions. Results also show that the inland surface waters and inner archipelago waters within Stockholm County are a considerable source of greenhouse gases to the atmosphere. A better understanding of these water emissions is necessary to formulate effective planning and policy measures that can reduce urban emissions. The insights gained from this study can also be applied in other regions. In particular, water bodies could play a significant role in the urban carbon cycle and using this knowledge for more complete carbon accounting, and a better understanding of green-blue interactions could help to reduce net urban emissions in many places.

在平衡城市发展的双重目标以容纳不断增长的人口，同时实现城市碳中和时，了解参与城市碳循环的复杂人类系统与自然系统之间的相互作用非常重要。本研究开发了一种系统分解核算方法来评估城市碳循环。该方法有助于更好地了解此循环中涉及的系统内部和系统之间的复杂相互作用，从而确定人类可以如何调整其相互作用以减少城市地区温室气体净排放的方式。通过对瑞典斯德哥尔摩县的系统故障核算方法进行测试，我们发现它为该地区与城市蓝绿色区域之间的碳相互作用提供了新的见解。结果表明，如果绿地保护其碳固存潜力并保持其能抵消预计的剩余活性排放量，那么斯德哥尔摩县如何减少排放并实现当地碳净中和的目标。结果还表明，斯德哥尔摩县内陆地表水和群岛内水是向大气排放温室气体的重要来源。要制定有效的规划和政策措施以减少城市排放，必须对这些水的排放有更好的了解。从这项研究中获得的见解也可以应用于其他地区。特别是水体可以在城市碳循环中发挥重要作用，并利用这些知识进行更完整的碳核算，