Low-Carbon Territorial Spatial Detailed Planning in the Context of Climate Change: A Case Study of the Wenzhou Garden Expo Park Area, China

Abstract

In the context of global climate change, promoting the low-carbon transformation of cities has become an important strategy to cope with environmental challenges. This paper takes Wenzhou Garden Expo Park area as the research object, combines its practical experience as a pilot of a national low-carbon city, and discusses how to effectively control carbon emission in the spatial planning of national territory. The study systematically evaluated the impact of different land use types and development intensities on carbon emissions, as well as the relationship between daytime temperature and carbon emissions, by constructing a carbon emission measurement model and a random forest regression model. This evaluation was based on an analysis of remote sensing data and land use changes from 2000 to 2023. The results show that between 2000 and 2023, the carbon emission from building land in the Garden Expo Park area will increase by about 70%, while the carbon emission can be reduced by more than 25% through rational land use layout and development intensity control. At the same time, the expansion of green space and forest land increases the carbon sink capacity by about 16.7%. With rising temperatures, carbon emissions exhibit a significant upward trend. This study suggests that specific optimization strategies for low-carbon planning, along with an indicator system—particularly through increasing the allocation of green spaces such as arboreal forests and parks—can significantly improve regional carbon balance. This study may provide a reference for other rapidly urbanizing regions to balance economic development and carbon emissions.

1. Introduction

Global climate change has become a focal point of attention for countries worldwide [1]. Particularly under the impetus of international climate agreements such as the Paris Agreement, the urgency to reduce greenhouse gas emissions is intensifying [2,3]. Land use planning, as a critical link between human activities and the natural environment, has a direct impact on the balance between carbon emissions and carbon sequestration [4]. Against the background of intensifying global climate change, low-carbon development has become a core issue in urban planning and sustainable development. Carbon emission, as the main driver of climate warming, has been highly valued by countries all over the world, and controlling carbon emission and promoting low-carbon urban transformation have become important objectives of current urban planning [2,5,6,7,8]. Especially in the context of rapid urbanization, how to promote economic growth while effectively controlling carbon emissions has become a huge challenge for all countries [9,10]. Low-carbon spatial planning has gradually become an important strategy in addressing climate change, aiming to reduce carbon emissions and promote carbon sequestration through rational land development and management.

In recent years, research on low-carbon land use planning has progressively expanded on a global scale. As major contributors to urban emissions, the transport, construction, and industrial sectors play a vital role in carbon management [11]. Transport emissions stem from fossil fuel combustion in vehicles, while construction emissions are often attributed to high-carbon materials like cement and steel [12]. Industrial emissions are driven by energy demands for manufacturing processes [13]. Each sector’s emission profile impacts urban carbon strategies, emphasizing the need for integrated, sector-specific approaches in spatial planning [14]. The characteristics of carbon emissions and absorption associated with different types of land use have become a central focus of research [2,5]. Research findings are primarily concentrated in the following areas: Urban and Regional Land Use Planning: Studies indicate that compact urban development and intensive land use management strategies can significantly reduce urban carbon emissions [15,16]. Additionally, many scholars have suggested that interdepartmental coordination should be strengthened to integrate low-carbon development into national land planning systems, thereby enhancing policy effectiveness [17,18]. Rural and Agricultural Land Use: Optimizing the allocation of agricultural land to reduce carbon emissions from agricultural activities is another key research focus [19,20,21,22]. Studies show that developing low-carbon agricultural technologies not only reduces greenhouse gas emissions but also improves soil quality and increases agricultural productivity [4,23,24,25,26]. Restoration of Natural Ecosystems: The restoration of degraded forest and wetland ecosystems can not only restore their carbon sequestration functions but also enhance biodiversity [27,28,29,30]. Some scholars have highlighted that, in the context of climate change, ecosystem restoration has become a critical strategy [7,31,32,33]. Establishment of Land Use and Carbon Emission Models: To better assess carbon emissions and sequestration levels under different land use scenarios, many scholars have developed mathematical models that link land use and carbon emissions using tools such as remote sensing and geographic information systems (GIS) [8,14,34,35,36,37]. These models provide a scientific basis for formulating low-carbon land use policies [38,39]. Land Management and Carbon Sequestration: Agriculture and forestry are two major carbon sequestration domains [40,41]. Through refined agricultural management, vegetation restoration, and increasing land cover, carbon sequestration can be effectively increased [42,43]. Notably, the protection and restoration of wetlands are regarded as an efficient means of carbon sequestration, due to their significant carbon fixation capacity [44,45,46]. Low-carbon land use planning plays a crucial role in addressing climate change. By optimizing land use, enhancing carbon sequestration capacity, and reducing carbon emissions, it can effectively mitigate the impacts of climate change [13,47].

Low-carbon land use planning plays a crucial role in addressing climate change. By optimizing land use, enhancing carbon sequestration capacity, and reducing carbon emissions, it can effectively mitigate the impacts of climate change [48,49,50]. As one of the pilot low-carbon cities in China, Wenzhou has achieved remarkable results in low-carbon development and carbon emission control in recent years. Wenzhou is not only facing the pressure of energy consumption and carbon emission growth in the process of urbanization, but also shouldering the important task of exploring the transformation of low-carbon cities. Wenzhou’s special geographical location and economic development characteristics make it an ideal case for low-carbon city planning research. However, despite the results achieved in the low-carbon pilot project, the existing planning system still fails to adequately incorporate carbon emission control into specific spatial planning, especially at the level of detailed planning, and lacks systematic research and control tools for the relationship between land use and carbon emissions [33,50,51].

With the advancement of spatial planning, detailed planning has become one of the core tools for urban development and land management [26,52]. It not only plays a key role in the regulation of land use and development intensity, but is also expected to play an important role in the future low-carbon development of cities. Therefore, how to effectively incorporate the control mechanism of carbon emission in the detailed land space planning has become a core issue to promote the construction of low-carbon cities.

Based on the existing research foundation and the actual conditions of Wenzhou, this study focuses on the Garden Expo Park area of Wenzhou as the research subject. By constructing a carbon emission measurement model and a random forest regression model, and combining remote sensing data and land use change analysis from 2000 to 2023, this paper systematically evaluates the impact of different land use types and development intensities on carbon emissions, as well as the relationship between daytime temperature and carbon emissions. The potential innovations of this study are as follows: (1) Practice-oriented: The research subject is the Garden Expo Park area in Wenzhou, which, as a national low-carbon city pilot, brings practical value to the study. The findings not only provide specific carbon emission control strategies for Wenzhou but also serve as a reference for the planning of other low-carbon cities. (2) Comprehensive analysis method: The study employs a carbon emission measurement model and a random forest regression model, integrating remote sensing data with land use change analysis to ensure the multidimensional nature of the data and the scientific rigor of the results. This multi-model approach enhances the accuracy of predictions. (3) Multidimensional factor consideration: In addition to focusing on the impact of land use types and development intensities on carbon emissions, the study also explores the relationship between daytime temperature and carbon emissions. This multifactor analysis helps to more comprehensively understand the complex interactions between land use and climate change.

2. Study Area and Data

2.1. Study Area

Wenzhou is located on the southeast coast of China in Zhejiang Province, spanning latitudes 27°03′ to 28°36′ N and longitudes 119°37′ to 121°18′ E (Figure 1a), covering a total area of approximately 12,103 square kilometers. The region features diverse topography, including mountains, hills, plains, and coastline. Wenzhou experiences a subtropical monsoon climate, characterized by warm and humid conditions, with an average annual temperature of around 18 °C and annual precipitation ranging from 1600 to 1700 mm. As one of the key cities in Zhejiang Province, Wenzhou has been designated a national low-carbon city pilot since 2012. In recent years, Wenzhou has experienced rapid economic growth, with a GDP of RMB 873 billion in 2023, growing at an annual rate of about 6%. The city’s key industries include machinery manufacturing, electronics, and fashion goods. With the acceleration of urbanization, the land use structure has gradually shifted from agricultural to urban development, with increasing emphasis on ecological protection and the planning of green spaces. Wenzhou has incorporated low-carbon development concepts into its territorial spatial detailed planning, aiming to balance urban growth with carbon emission control.

The Garden Expo Park area in western Wenzhou (Figure 1b) is located in the Western Ecological New City, covering an area of approximately 350 hectares. It is planned as an ecological demonstration zone and urban recreational area. Situated near the Wenzhou administrative center with convenient transportation, the Garden Expo Park is a key node in the city’s spatial expansion. The planning of this area emphasizes ecological protection, integrating urban green spaces, wetland parks, recreational facilities, and low-carbon communities. It aims to create a harmonious balance between humans and nature as a low-carbon demonstration zone. As urbanization advances, this area has emerged as a new growth pole for Wenzhou’s green economy and tourism sector. The introduction of green buildings, renewable energy applications, and other low-carbon technologies enhances the carbon sequestration capacity of the region while reducing carbon emissions. The development model of the Garden Expo Park not only aligns with Wenzhou’s broader low-carbon development strategy but also serves as a valuable demonstration for other cities in low-carbon planning and management.

2.2. Data Sources

This study’s data are derived from various sources, covering carbon emission data, remote sensing imagery, and geographic information related to territorial spatial planning. First, carbon emission data were obtained from the official statistical yearbooks of Wenzhou (www.wenzhou.gov.cn (accessed on 20 August 2024)), publicly available data from the Environmental Protection Department (https://sthjj.wenzhou.gov.cn/ (accessed on 20 August 2024)), and historical energy consumption data provided by relevant agencies, spanning the years 2000 to 2023. These data include annual carbon emissions from different economic sectors within Wenzhou, providing the basis for analyzing and forecasting carbon emission trends. Additionally, remote sensing imagery of the Wenzhou region was primarily sourced from the Landsat 8 satellite data provided by the United States Geological Survey (USGS), covering the period from 2000 to 2023, with a spatial resolution of 30 m [45,48]. The data processing involved radiometric calibration, geometric correction, and atmospheric correction to ensure the accuracy and consistency of the remote sensing data.

To more precisely analyze the relationship between carbon emissions and land use, the study also utilized territorial spatial planning data provided by the National Bureau of Statistics and the Ministry of Natural Resources (https://zrzyj.wenzhou.gov.cn (accessed on 20 August 2024)), which includes data on land use changes and development intensity from 2000 to 2023. Remote sensing data collection and preprocessing were conducted using the Google Earth Engine (GEE) platform. This platform was used to extract key ecological indicators such as the Fraction of Vegetation Cover (FVC) and the Normalized Difference Vegetation Index (NDVI) for Wenzhou and the Garden Expo Park area through spatiotemporal analysis. Furthermore, foundational geographic information data, including administrative boundaries, roads, rivers, and infrastructure, were sourced from the latest urban planning maps provided by the Wenzhou Municipal Bureau of Natural Resources and Planning. This ensured the accuracy and reliability of the spatial analysis results for the study area.

3. Research Methods

3.1. Calculation of Carbon Emission and Carbon Storage Trends

To comprehensively assess the carbon emissions and carbon storage situation in Wenzhou, this study conducted trend calculations for both. The calculation of carbon storage relied on land use data from Wenzhou, particularly focusing on ecological land types such as forests, wetlands, and green spaces, which are critical for carbon sequestration [14,53,54]. The total amount of carbon storage can be represented as follows:

$$S_t=\sum _{i=1}^m{A}_{i,t}·S_i$$

(1)

where ${\mathrm{S}}_{\mathrm{t}}$ represents the total carbon storage for year $\mathrm{t}$, ${\mathrm{A}}_{\mathrm{i},\mathrm{t}}$ denotes the area of the i-th type of ecological land in year $\mathrm{t}$, ${\mathrm{S}}_{\mathrm{i}}$ and is the carbon sequestration capacity per unit area (tons/hectare) of the i-th land type, and with $\mathrm{m}$ being the number of ecological land types (including forests, wetlands, green spaces, etc.). The carbon sequestration capacity per unit area ${\mathrm{S}}_{\mathrm{i}}$ is determined from relevant literature and local carbon sink observation data.

Through trend analysis of the carbon storage data, Wenzhou’s total carbon storage has shown a gradual increase over the years, primarily due to the implementation of ecological protection policies and the continuous expansion of urban green space. Particularly since 2010, Wenzhou has vigorously promoted ecological environmental protection and vegetation restoration projects, resulting in a steady increase in forest cover, which has become a major source of carbon sink growth [23,38]. Specifically, this study used remote sensing imagery from different years to extract the areas of forests, green spaces, and wetlands in Wenzhou, and combined these with carbon sequestration coefficients to calculate the total carbon storage for each year [35,55]. Additionally, we conducted linear regression analysis on carbon storage trends across different periods to obtain the rate of change in carbon storage, expressed by the following formula:

$$∆S=S_{t+k}-S_t$$

(2)

where $∆\mathrm{S}$ represents the change in carbon storage between the years $\mathrm{t}$ and $\mathrm{t}+\mathrm{k}$, ${\mathrm{S}}_{\mathrm{t}+\mathrm{k}}$ is the total carbon storage in the future year $\mathrm{t}+\mathrm{k}$, and ${\mathrm{S}}_{\mathrm{t}}$ is the total carbon storage in year $\mathrm{t}$. Through an analysis of carbon storage trends, we found that Wenzhou’s carbon storage has been steadily increasing at an annual rate of approximately 0.5% to 1%, indicating that the carbon sequestration capacity of its ecological land is improving year by year.

3.2. Prediction of Carbon Emission and Carbon Storage Based on Machine Learning

In this study, we used the Random Forest Regression model to predict the future carbon emissions and carbon storage in Wenzhou [19,55]. Random Forest is an ensemble learning method that improves prediction accuracy and stability by constructing multiple decision trees. Its advantage lies in its ability to handle high-dimensional data and effectively capture the complex nonlinear relationships between input variables and target variables [26,56].

3.3. Data Preparation

The input data for the model covered historical carbon emissions and carbon storage data for Wenzhou from 2000 to 2023, along with related land use, economic, and meteorological data. The main input features included the area of different land use types (industrial land, residential land, transportation land, green spaces, etc.), economic development indicators (such as GDP, population density), meteorological data (such as annual average temperature, annual precipitation), and energy structure (such as the proportion of renewable energy) [14,22,43]. Before training the model, all data were standardized to ensure that different features were on the same scale.

3.4. Construction of the Random Forest Model

The Random Forest model generates a large number of decision trees to make predictions, with each tree trained on a random subset of the input data and a random subset of the features [16,44,46]. The prediction formula is given by the following:

$${\widehat{E}}_{t+k}={\displaystyle \frac{1}{N}}{\sum }_{n=1}^N{T}_n\left(X_{t+k}\right)$$

(3)

$${\widehat{S}}_{t+k}={\displaystyle \frac{1}{N}}{\sum }_{n=1}^N{T^{\prime }}_n\left(X_{t+k}\right)$$

(4)

where ${\widehat{\mathrm{E}}}_{\mathrm{t}+\mathrm{k}}$ represents the predicted carbon emissions, and ${\widehat{\mathrm{S}}}_{\mathrm{t}+\mathrm{k}}$ represents the predicted carbon storage for year $\mathrm{t}+\mathrm{k}$. ${\mathrm{X}}_{\mathrm{t}+\mathrm{k}}$ denotes the input features for year $\mathrm{t}+\mathrm{k}$, and ${\mathrm{T}}_{\mathrm{n}}$ and ${{\mathrm{T}}^{\prime }}_{\mathrm{n}}$ represent the n-th decision tree in the forest. $N$ is the total number of trees in the Random Forest model. During the generation of each tree, a random subset of features and samples is selected, and this randomization mechanism improves the generalization ability of the model.

3.5. Model Training and Evaluation

During the training process, this study used data from 2000 to 2015 as the training set and data from 2016 to 2023 for validation. To prevent overfitting, hyperparameters such as the maximum depth of the trees and the number of trees were tuned, and the optimal parameter combination was selected through cross-validation. The model evaluation used Mean Squared Error (MSE) and the coefficient of determination (R²) as evaluation metrics [31,44,57]. The formulas for these metrics are as follows:

$$MSE={\displaystyle \frac{1}{n}}{\sum }_{i=1}^n{({\widehat{y}}_i-y_i)}^2$$

(5)

$$R^2=1-{\displaystyle \frac{\sum _{i=1}^n{(y_i-{\widehat{y}}_i)}^2}{\sum _{i=1}^n{(y_i-{\overline{y}}_i)}^2}}$$

(6)

where ${\widehat{\mathrm{y}}}_{\mathrm{i}}$ is the predicted value, ${\mathrm{y}}_{\mathrm{i}}$ is the actual value, and ${\overline{\mathrm{y}}}_{\mathrm{i}}$ is the mean of the observed values.

3.6. Construction of Low-Carbon DetailedPlanning Indicators

The low-carbon planning design framework (Figure 2) systematically analyzes the sources, causes, influencing factors, and control strategies of carbon emissions, constructing a comprehensive planning pathway. Firstly, the framework categorizes carbon-emitting sectors into industry, public buildings, public transportation, and green spaces, covering the main sources of urban carbon emissions and carbon sinks. However, this framework primarily considers operational carbon emissions and does not include a substantial portion of “embodied carbon” in the built environment, such as emissions embedded in construction materials and hard infrastructure. These emissions, which are often “locked in” during the planning phase, account for approximately 70% of total emissions [58]. Excluding them from the framework may lead to an underestimation of total carbon emissions. Therefore, we suggest that embodied carbon from building materials and infrastructure be incorporated into the framework to provide a more comprehensive assessment of emission sources.

Secondly, the core cause of carbon emissions is attributed to energy consumption, including residential, public, and commuting energy use, as well as the carbon sequestration role of plants and soil. Subsequently, the framework further analyzes influencing factors such as scale, efficiency, and intensity, involving land type, area, and the application of new technologies. It also proposes control indicators, such as land use type, population density, and green space ratio. Supporting policies for the reuse and recycling of building materials can significantly reduce embodied carbon loads in new developments, while effectively controlling building size, transportation infrastructure, and energy consumption intensity to manage emissions more comprehensively.

4. Results

4.1. Spatiotemporal Variation in Carbon Emissions Across Different Sectors

Figure 3 illustrates the carbon emission trends of Wenzhou’s construction, industrial, and transportation sectors. From 2000 to 2023, carbon emissions from the construction sector (Figure 3a) gradually increased from approximately 2.5 million tons to 5 million tons, showing a steady growth trend. This reflects advancements in energy-efficient building technologies and increased incorporation of sustainable materials, though substantial opportunities remain to further reduce emissions, particularly through optimizing operational energy use in buildings.

The industrial sector (Figure 3b) exhibited the most significant increase in carbon emissions, rising from about 10 million tons in 2000 to over 30 million tons by 2023, demonstrating the sector’s high dependence on fossil fuels. As the primary source of carbon emissions, future efforts to reduce emissions in the industrial sector should focus on industrial restructuring, improving energy efficiency, and promoting clean production technologies.

In the transportation sector (Figure 3c), carbon emissions increased from about 4 million tons in 2000 to 12 million tons by 2023. This upward trend is largely driven by the increase in vehicle ownership and road traffic congestion. To curb emissions in the transportation sector, it is crucial to accelerate the adoption of clean energy vehicles, optimize public transportation systems, and promote low-carbon modes of transport.

A comparison of the carbon emissions data across these three sectors reveals that the industrial sector experienced the fastest rate of increase, followed by transportation, while the construction sector showed a relatively slower growth rate. The total emissions from the industrial and transportation sectors are significantly higher and exhibit more pronounced increases, indicating that these two sectors will be the key focus areas for Wenzhou’s future low-carbon development plans.

4.2. Carbon Emission Estimation Under Conventional Land Use

As shown in Figure 4, the carbon emissions and carbon storage trends across different land use types in Wenzhou exhibit significant variations. In Figure 4a, carbon emissions from construction land have steadily increased from approximately 0.20 million tons of CO₂ in 2000 to 0.34 million tons of CO₂ in 2023, a 70% rise. This reflects the growing energy consumption and material production associated with urbanization and construction activities. The continuous growth in construction land emissions is closely related to increased building density, construction energy use, and urban infrastructure expansion, highlighting the need for broader adoption of energy-saving technologies and low-carbon building materials to control this trend in the future.

In contrast, the carbon emissions from agricultural land (Figure 4b) display notable fluctuations, ranging from 0.07 to 0.14 million tons of CO₂, nearly doubling over time. These fluctuations may be attributed to seasonal variations in agricultural activities, climate conditions, and the use of fertilizers and machinery in agricultural production. Although there is no clear long-term trend, the instability of emissions from agricultural land indicates the challenges of traditional farming in carbon management. Future efforts could focus on promoting eco-friendly agricultural practices and reducing fertilizer use to stabilize or even decrease emissions from this sector.

Forested land shows a distinctly different pattern, acting as a consistent carbon sink. Figure 4c indicates that carbon storage in forested land remained stable between −0.45 and −0.375 million tons of CO₂ from 2000 to 2023. This demonstrates that forest vegetation plays a crucial role in Wenzhou’s carbon neutrality efforts by maintaining a stable carbon sequestration capacity. However, fluctuations in carbon storage suggest that ecological conditions in certain years might have been affected. Strengthening forest protection and enhancing vegetation restoration will be vital to preserving and boosting this carbon sink function.

Figure 4d provides a comprehensive view of the overall carbon emissions and carbon storage trends in Wenzhou from 2000 to 2023. The data show that total carbon emissions increased from around 2.4 million tons of CO₂ in 2000 to approximately 4.4 million tons of CO₂ in 2023, representing an 83% increase. Meanwhile, carbon storage remained stable between −0.45 and −0.35 million tons of CO₂ without significant growth. This imbalance between rising carbon emissions and stagnant carbon storage exacerbates the overall carbon pressure in Wenzhou. The rapid growth in emissions from construction land and agricultural land further worsens the carbon balance. Although forested land has provided some offset through its carbon sequestration capacity, its growth is far outpaced by the increase in emissions.

In light of these findings, it is clear that Wenzhou’s low-carbon development urgently requires stricter measures to control emissions from construction and agricultural land. Additionally, further enhancing carbon storage in forested land, expanding green space, and promoting green infrastructure development will be key to achieving carbon neutrality. The widening gap between fast-growing emissions and lagging carbon storage indicates that Wenzhou must accelerate the implementation of green technologies, low-carbon buildings, and sustainable land use strategies to meet the goals of low-carbon urban development without compromising economic growth.

4.3. Prediction of Overall Land Use Carbon Emissions and Carbon Storage

As shown in the data from Figure 5, Wenzhou’s carbon emissions and carbon storage exhibit significant differences between 2000 and 2035. The green dashed line represents carbon emissions, which remained at approximately 0.3 million tons of CO₂ from 2000 but began to rise gradually from 2015 onwards. This increase accelerates notably after 2023, with projected emissions exceeding 0.6 million tons of CO₂ by 2035—an increase of nearly 100%. This trend indicates that as urbanization accelerates, the rise in high-energy-consuming activities such as industrial production, construction, and transportation will lead to a significant uptick in carbon emissions. Particularly after 2030, a rapid surge in emissions is likely.

The red dashed line represents carbon storage, which remained relatively stable between −0.4 and −0.6 million tons of CO₂ from 2000 to 2023, with some fluctuations but overall minor changes. This indicates that the growth in Wenzhou’s carbon sequestration capacity—mainly from forests and green spaces—has been limited. Notably, after 2023, carbon storage shows a slight decline, reflecting that the potential for enhancing the ecosystem’s carbon sink capacity has not been fully realized.

From this data, it is clear that Wenzhou’s carbon emissions will continue to increase in the future, while carbon storage growth will not be sufficient to counterbalance this trend. This highlights the need for strong low-carbon policies and large-scale ecological protection measures. Without such efforts, the imbalance between carbon emissions and carbon storage will further intensify. Therefore, Wenzhou must prioritize the promotion of energy-saving and emission-reduction technologies and significantly increase forest and green space areas to enhance its carbon sequestration capacity and address the growing pressure of carbon emissions in the future.

4.4. Estimation of Land Use Carbon Emissions Under Low-Carbon Planning Design

To reduce carbon emissions and achieve carbon neutrality earlier, we implemented a low-carbon planning design for the Garden Expo Park area in Wenzhou. As shown in the 2021 and 2023 low-carbon detailed planning maps in Figure 6a,b, Wenzhou has increased carbon sink land use types such as tree-covered areas, parks, and green spaces, gradually enhancing carbon storage capacity. Additionally, adjustments were made to optimize high-carbon-emission land use such as industrial and urban residential areas.

According to the data in Figure 6c, carbon emissions in 2021 were 0.008 million tons of CO₂, while carbon storage stood at −0.003 million tons of CO₂. By 2023, carbon emissions had dropped to 0.006 million tons of CO₂, and carbon storage had risen to −0.0035 million tons of CO₂, representing a 25% reduction in emissions and a 16.7% increase in storage. These figures reflect the initial success of Wenzhou’s low-carbon planning, particularly in terms of reducing carbon emissions. However, while carbon storage has increased, the growth remains modest, indicating that the enhancement of carbon sequestration capacity is still limited.

For future low-carbon development, Wenzhou should continue to expand carbon sink land areas and reduce high-carbon-emission activities to achieve further carbon balance. This will ensure effective control of carbon emissions as the city undergoes urbanization and industrialization, steadily progressing toward its carbon neutrality goals.

4.5. Comparison of Carbon Emissions and Carbon Storage Under Two Scenarios

Figure 7a,b clearly show the significant differences in carbon emissions and carbon storage between the low-carbon scenario and the conventional scenario in 2021 and 2023. In the low-carbon scenario, carbon emissions in 2021 are approximately 0.005 million tons of CO₂, with carbon storage at −0.0025 million tons of CO₂, indicating that following a low-carbon development pathway effectively controlled emissions while improving carbon storage capacity. In contrast, under the conventional scenarios 1 and 2, carbon emissions reach 0.01 million tons of CO₂ and 0.0125 million tons of CO₂, respectively, much higher than in the low-carbon scenario, with significantly weakened carbon storage capacities of −0.0015 million tons CO₂ and −0.001 million tons CO₂. This suggests that rapid increases in carbon emissions and insufficient carbon sequestration capacity under the conventional development model will exacerbate carbon emission pressure. The data from 2023 further confirm this trend, showing that carbon emissions and carbon storage in the low-carbon scenario outperform both conventional scenarios, demonstrating the strong emission-reduction effects of the low-carbon pathway. Meanwhile, the growth of emissions under the conventional scenarios puts further stress on carbon balance.

Figure 7b displays the projected trend of carbon emissions and carbon storage from 2021 to 2030 under the low-carbon scenario. Carbon emissions are expected to decrease from 0.0085 million tons of CO₂ in 2021 to 0.003 million tons of CO₂ by 2030, a reduction of nearly 65%, illustrating that under the guidance of low-carbon policies, Wenzhou will achieve significant reductions in emissions over the next decade. Simultaneously, carbon storage will increase from −0.0035 million tons of CO₂ in 2021 to −0.0075 million tons of CO₂ by 2030, nearly doubling, indicating that through measures such as expanding green spaces and restoring forests, Wenzhou’s carbon sequestration capacity will be greatly enhanced. These projections further highlight the importance of low-carbon policies in achieving future carbon neutrality targets.

Figure 8a–d show the spatial distribution of carbon emission and carbon storage for each type of use in the land use planning of the Wenzhou Garden Expo Park area in 2021, respectively. Combined with the data analysis in Figure 7a,b, the low-carbon development scenario has obvious advantages compared with the conventional scenario, which can not only significantly reduce carbon emissions but also enhance the carbon storage capacity. In the conventional scenario, both in 2021 and 2024, the growth rate of carbon emissions far exceeds the rate of carbon stock enhancement, reflecting the fact that the pressure on Wenzhou’s carbon emissions will gradually intensify if it continues to develop according to the existing high-carbon model. Conversely, in the low-carbon scenario, although emissions fluctuate over time, they generally show a downward trend, while carbon storage continues to rise, demonstrating that implementing low-carbon policies can effectively control emission growth and increase carbon sequestration through ecosystem improvements.

Therefore, Wenzhou’s future low-carbon development plans should continue to promote energy-saving and emission-reduction policies while expanding green spaces and improving the carbon sequestration capacity of ecosystems to balance carbon emissions and carbon storage. Considering the projected trends in emissions and storage, it can be anticipated that with the continued implementation of strict low-carbon policies, Wenzhou will be able to significantly reduce carbon emissions and enhance carbon storage capacity by 2030, laying a solid foundation for achieving carbon neutrality.

4.6. Analysis of Temperature Variation and Carbon Emissions on a Diurnal Scale

To further explore the relationship between daytime temperature and carbon emissions in low-carbon planning, and to verify that low-carbon planning helps reduce temperatures and indirectly decreases carbon emissions, we specifically selected three summer dates: 15 June (Figure 9a), 15 July (Figure 9c), and 15 August (Figure 9e). The temperature variations on these days exhibit distinct diurnal patterns. As observed in Figure 8, temperatures steadily rise throughout the day, peaking in the afternoon and then gradually declining. Specifically, the temperature on 15 June was relatively mild, fluctuating between 20 °C and 30 °C. In contrast, the temperature fluctuations on 15 July and 15 August were more pronounced, particularly on 15 August, where temperatures varied dramatically between 24 °C and 32 °C, with daily highs consistently exceeding 30 °C.

This pattern of temperature variation was also reflected in the changes in carbon emissions. The fitting results of temperature and carbon emissions indicate that as temperatures increase, carbon emissions show a significant upward trend. According to the statistical indicators of the fitted model, the R² value for 15 June was 0.86 (Figure 9b), while for both 15 July and 15 August, the R² values were 0.88 (Figure 9d,f), indicating a highly significant positive correlation between temperature and carbon emissions. The p-values for all three days were 0.0000, demonstrating that this correlation is statistically highly significant.

Additionally, the confidence intervals of the fitted curves indicate the reliability of the model’s predictions, especially during July and August, when the increase in carbon emissions was more pronounced as temperatures rose. This suggests that high temperatures have a stronger promoting effect on carbon emissions. Comparing the three dates, the impact of temperature on carbon emissions was more intense in July and August, with faster increases in carbon emissions under higher temperatures. Although the temperature rise on 15 June also significantly contributed to the increase in carbon emissions, the smaller temperature increment resulted in a relatively milder impact compared to July and August. This difference may be related to the increased energy consumption during hot seasons, such as the widespread use of air conditioning, which significantly boosts electricity demand during high-temperature periods, leading to a rapid increase in carbon emissions.

5. Discussion

5.1. Continuous Growth of Carbon Emissions and the Limited Effect of Policy Regulation

Since 2000, Wenzhou’s carbon emissions have exhibited a continuous upward trend, particularly in sectors such as industry, transportation, and construction. The data show that between 2000 and 2023, the city’s total carbon emissions increased from 20.5 million tons of CO₂ to 30.5 million tons of CO₂, an increase of 49%. This growth largely reflects the significant role that industrial and construction activities play in driving carbon emissions during rapid urbanization. Industrial emissions rose by approximately 85%, and transportation emissions increased by around 60% during this period. Although Wenzhou implemented several low-carbon policies in 2021, which slowed the rate of carbon emissions growth from 5% to 2.9% by 2023, the overall impact of these policies has been limited. They have not been able to fully curtail the increase in emissions. While the policies have mitigated some of the rapid growth in carbon emissions, their effects remain localized and short-term, failing to establish a systematic, long-term low-carbon development trajectory [45,50]. This finding underscores the need for Wenzhou to adopt more stringent carbon reduction measures at the policy level, especially in high-emission sectors such as industry, transportation, and construction, to balance economic growth with effective carbon mitigation [59,60].

5.2. Improvement in Carbon Storage Capacity and Its Realistic Limitations

Wenzhou has made notable progress in increasing its carbon storage capacity by expanding carbon sink areas such as forests, parks, and green spaces. Between 2000 and 2023, the city’s carbon storage capacity increased from −0.003 million tons of CO₂ to −0.0035 million tons of CO₂, representing a 16.7% increase. This reflects the role that expanded ecological lands, such as forests and green spaces, play in alleviating carbon emissions pressure by enhancing the city’s carbon sink capacity. However, the rate of growth in carbon storage is far slower than that of carbon emissions. This imbalance highlights a critical limitation: the modest increase in carbon storage cannot offset the large volume of emissions produced by industrialization and urbanization, especially in the context of rapid industrial and construction land expansion. The city’s current carbon sink efforts appear insufficient in addressing the emissions surge, particularly from high-emission sectors. This limitation suggests that Wenzhou must not only further expand forested and green areas but also enhance the efficiency of existing carbon sink lands through more advanced ecological restoration techniques [29,61]. Measures such as soil rehabilitation and wetland conservation could further strengthen the land’s ability to sequester carbon. Without a more systemic and enhanced approach to improving carbon storage capacity, Wenzhou risks exacerbating the gap between carbon emissions and carbon sinks, hindering progress towards sustainable environmental goals.

5.3. The Effect of Rising Temperatures on Carbon Emissions and Response Strategies

The fitting analysis of summer temperatures and carbon emissions in Wenzhou demonstrates a direct relationship between rising temperatures and increased carbon emissions. For example, in July 2023, when the average daily temperature reached 32 °C, the city’s carbon emissions rose to 0.55 million tons of CO₂, compared to 0.48 million tons of CO₂ in April of the same year—a 14.6% increase. This significant rise in carbon emissions due to temperature increases can be attributed primarily to higher energy demand, especially the extensive use of air conditioning and other electrical devices during hot weather, which, in turn, boosts energy consumption. Additionally, industrial activities tend to continue unabated during high-temperature periods, further exacerbating carbon emissions. These findings highlight the compounding effect of rising temperatures on energy demand and carbon emissions, particularly in the summer months. It is essential for Wenzhou to prioritize strategies aimed at mitigating this temperature–emissions link. In particular, building energy efficiency must be improved, with a focus on promoting green buildings and renewable energy solutions. For example, retrofitting building insulation and promoting solar energy use could help reduce the excessive reliance on electricity and energy during high-temperature periods. Moreover, expanding urban green spaces to alleviate the urban heat island effect can further reduce energy demand, thus lowering carbon emissions during periods of extreme heat [38,62,63].

6. Conclusions

Wenzhou has made significant strides in low-carbon development, yet it still faces the challenging reality of rising carbon emissions. From 2000 to 2023, Wenzhou’s carbon emissions increased from 20.5 million to 30.5 million tons of CO₂, a 49% rise. Although the low-carbon policies introduced in 2021 successfully reduced the annual growth rate from 5% to 2.9% by 2023, the overall trend remains upward. Carbon storage has also seen slight improvement, increasing from −0.003 million tons of CO₂ in 2000 to −0.0035 million tons in 2023—a 16.7% rise. However, this modest growth in carbon storage is insufficient to offset the rapid emissions increase, leading to an ever-widening gap between emissions and storage, indicating that Wenzhou’s current carbon balance strategies require further optimization.

The impacts of various land use types on carbon emissions and storage vary significantly: industrial and construction lands contribute 35% and 28% of total emissions, respectively, while forest and park lands account for 45% and 30% of carbon storage. These disparities highlight the critical role of land use planning in carbon management and suggest the potential of reallocating land use to maximize carbon storage capacity. Given the frequency of high temperatures in recent years, seasonal spikes in carbon emissions are becoming more pronounced. For instance, in July 2023, emissions reached 0.55 million tons of CO₂, 14.6% higher than in April of the same year, underlining the impact of high temperatures on carbon emissions. This underscores the need for targeted energy and carbon-reduction measures during periods of intense heat.

To meet these challenges and achieve carbon peak and neutrality goals, Wenzhou should adopt a multi-tiered strategy. This includes expanding carbon sink lands, such as increasing forested and green infrastructure areas to enhance carbon storage capacity, as well as optimizing energy use, particularly by implementing energy-saving measures during seasonal temperature peaks. Future policy formulation should address the dynamic interplay between land use and climate, drawing from successful international case studies to develop regional climate policies tailored to Wenzhou’s needs.