Objective  As an important tool for optimizing the territorial spatial pattern, territorial spatial planning has become a policy lever for promoting the achievement of the carbon peaking and carbon neutrality goals. However, from the current practice of territorial spatial planning in various regions, there is still a lack of consensus on how to implement the carbon peaking and carbon neutrality goals in planning. From the perspective of planning process, “dual evaluation” as a prerequisite research for territorial spatial planning is crucial for clarifying the background conditions of territorial spatial planning. However, existing guidelines and practices for “dual evaluation” often do not involve relevant content. From the results of territorial spatial planning at all levels, there are relatively few implementation plans directly incorporated into territorial spatial planning. From the perspective of planning hierarchy, the district and county levels are the key levels for implementing upper-level planning and ensuring smooth planning transmission. However, there has been relatively few research on planning response to the carbon peaking and carbon neutrality goals in territorial spatial planning at the district/county level. In summary, this research aims to clarify the methods for carbon source and sink accounting as well as carbon evaluation for district and county units, with Wuqing District, Tianjin as an empirical example. The major purpose is to help territorial spatial planning at the district/county level figure out “carbon”-related inventory and provide support for the formulation of “emission reduction and sink increase” strategies.

Methods  Firstly, based on the classification of land use types in the third national land resource survey, the calculation inventory of carbon source and carbon sink in Wuqing District, Tianjin is clarified. The carbon emission/absorption coefficient method is used to calculate the total carbon source and carbon sink of various district/county units in Wuqing District based on the aforesaid inventory. The analytic hierarchy process is performed to construct a carbon evaluation model, and comprehensively evaluate the carbon balance of each town/sub-district under the jurisdiction of Wuqing District based on data such as total carbon source and sink, population, land use, and economy. According to the carbon evaluation results, the low-carbon status of each towns/sub-district is graded, with the grading results being finally used to verify such contents as pattern optimization, indicator decomposition, and high-quality development strategy of the planning scheme.

Results  From the perspective of carbon source, the main carbon source comes from construction land, while the proportion of carbon source from farmland is relatively low. From the perspective of carbon sink, farmland, ditches, and wetlands have a higher amount of carbon absorption. From the perspective of carbon balance, there is a significant imbalance in the overall carbon balance of Wuqing District. The central urban area of Wuqing District, as well as Gaocun Town and Dawangguzhuang Town bordering Tongzhou in the north, play a negative role in carbon source consumption. Towns/sub-districts in the eastern, central western, and central northern parts of Wuqing District play a positive role in carbon source consumption throughout the district. In recent years, the Beijing-Tianjin-Hebei Urban Agglomeration has implemented expansion control of construction land in cross-border areas around the capital and put forward higher-level requirements for ecological restoration in border areas. The new master planning of Wuqing District has also implemented the above requirements, and towns near Tongzhou in Beijing have great potential in reducing emissions and increasing sinks in the future. From the carbon evaluation results, the sub-districts and towns in Wuqing District can be divided into five levels according to the carbon evaluation results. Overall, the low-carbon status of the entire district is distributed in three circle layers of “poor – good – poor” from the central urban area to the outside. The closer a town/sub-district is to the central urban area of Wuqing and Tongzhou in Beijing, the worse its low-carbon performance.

Conclusion  Due to population agglomeration, high proportion of construction land, and limited use of ditches, ponds, forests and other types of lands that play a carbon sink role, the central urban area has experienced the concentration of carbon source. The proportion of ecological land in the eastern, central western, and central northern parts of Wuqing District is relatively high, resulting in a significant carbon sink effect. In view of the carbon evaluation results, it is necessary to pay attention to both “carbon emission reduction” and “carbon sink increase” to improve the low-carbon status of towns/sub-districts. Based on the above research conclusions, the territorial spatial planning of Wuqing District should be based on the carbon evaluation level and development characteristics of each town/sub-district, and formulate low-carbon planning goals tailored to local conditions. As to the indicator decomposition of the entire district, the central urban area and peripheral towns/sub-districts are divided into two zones for differentiation and consideration. Carbon evaluation levels are used to decompose construction land indicators within each zone, and only additional factors are considered between zones. It is supposed to dig the potential of existing inefficient urban land, and adopt land conservation measures to develop and utilize existing construction land, in order to achieve an intensive territorial spatial pattern in Wuqing District that can guarantee urban development needs and slow down carbon source growth. Combined with the special planning of green space, greenway, etc., green spaces are inserted to increase the area and density of urban green spaces. For the national industrial parks in the central urban area, a green industry innovation fund will be established to inject funds into such industrial parks, with a focus on helping industrial parks in relevant towns/sub-districts with poor low-carbon status implement low-carbon transformation measures such as technological upgrading to reduce carbon emissions and improve resource utilization efficiency. For other industrial parks, supporting policies such as reward and punishment systems will be formulated based on carbon evaluation results and industrial output value to improve the enthusiasm and implementation supervision of low-carbon industrial transformation in various sub-districts and towns in Wuqing District.