The high-density development of urban centers has worsened outdoor thermal comfort in many cities. In this study, ENVI-met was used to simulate thermal comfort, and the universal thermal climate index (UTCI) and eight urban morphological indicators were calculated at 348 sampling points in the urban center. The correlation results are shown as follows: (1) Thermal comfort is significantly and positively correlated with impervious surface, green area ratio, and sky openness, showing a strong negative correlation with building density, floor area ratio, and shadow hours. (2) The UTCI value decreases by 0.998 °C for every 1 h increase in shadow hours, increases by 0.746 °C for every 10% increase in sky view factor, decreases by 0.462 °C when the building density increases by 10%, and decreases by 0.596 °C for every 10% increase in the impervious area ratio. (3) The sampling points with better thermal comfort have similar spatial characteristics such as higher building density, higher volume ratio, smaller green area ratio, longer shadow hours, and smaller sky openness. (4) In the planning and design of urban centers, increasing shade can improve the shadow hours in the environment. Specifically, large open sites should be avoided.

Climate change is a global problem facing mankind, and achieving peak CO₂ emissions and carbon neutrality is an important task for China to respond to global climate change. The quantitative evaluation of the trends of urban energy consumption and carbon emissions is a premise for achieving this goal. Therefore, from the perspective of urban expansion, this paper analyzes the complex relationship between the mutual interactions and feedback between urban population, land expansion, economic growth, energy structure and carbon emissions. STELLA simulation software is used to establish a system dynamics model of urban-level carbon emissions effects, and Changsha city is used for the case study. The simulated outputs of energy consumption and carbon emissions cover the period from 1949 to 2016. From 1949 to 2016, Changsha’s total energy consumption and carbon emissions per capita have continuously grown. The total carbon emissions increased from 0.66 Mt-CO₂ to 60.95 Mt-CO₂, while the per capita carbon emissions increased from 1.73 t-CO₂/10,000 people to 18.3 Mt-CO₂/10,000 people. The analysis of the structure of carbon emissions shows that the industrial sector accounted for the largest proportion of emissions, but it had gradually dropped from between 60% and 70% to about 40%. The carbon emissions of residential and commercial services accounted for less than 25%, and the proportion of transportation carbon emissions fluctuated greatly in 2013 and 2016. From the perspective of carbon emissions effects, carbon emissions per unit of GDP had a clear downward trend, from 186.11 t-CO₂/CNY10⁴ to 1.33 t-CO₂/CNY10⁴, and carbon emissions per unit of land showed two inflection points: one in 1961 and the other in 1996. The general trend showed an increase first, followed by a decrease, then a stabilization. There is a certain linear correlation between the compactness of urban shape and the overall trend of carbon emissions intensity, while the urban shape index has no linear correlation with the growth rate of carbon emissions. The carbon emissions assessment model constructed in this paper can be used by other municipalities, and the assessment results can provide guidance for future energy planning and decision making.

With the acceleration of urbanization, the disturbance to urban landscape patterns causes changes to urban surface runoff and increases the risk of urban waterlogging. We studied the response relationship between landscape pattern change and surface runoff in the Chang–Zhu–Tan metropolitan area for the period from 2000 to 2020, analyzing the driving factors that affected surface runoff. The influence of landscape pattern evolution on surface runoff was studied using the SCS-CN flow generation model, the moving window method, and Pearson’s analysis. The analysis showed that between 2000 and 2020, the forest area decreased, while the impermeable land area increased substantially. At the same time, the landscape spread degree (CONTAG) decreased, whereas the landscape fragmentation degree (DIVISION) increased, and the Shannon diversity index (SHDI) and landscape shape index (LSI) increased. The surface runoff in the main urban areas of Chang–Zhu–Tan increased substantially. The results showed that surface runoff is negatively correlated with SHDI, LSI, and DIVISION but displays a positive relationship to CONTAG. Soil texture and precipitation had the greatest impact on surface runoff. This study emphasizes the importance of landscape pattern evolution to surface runoff in rapidly developing metropolitan areas in terms of reducing surface runoff, alleviating urban waterlogging and preventing regional floods. Our research additionally seeks to optimize the landscape pattern of the Chang–Zhu–Tan metropolitan area.

Urban spatial expansion affects almost every dimension of sustainable urban development. A good grasp of the relationship between urban spatial evolution and carbon emissions can be the key to urban spatial governance. As a central city in the central region and a national low-carbon pilot city, Changsha has experienced a rapid expansion of construction land and growing carbon emissions. In this paper, four variable factors and five variable factors of carbon emission were used for the case city Changsha in 1979, 1996, 2003, 2008, 2013 and 2016. Based on the “double carbon” constraint target, the total carbon emissions, carbon-emission intensity and per capita carbon emission constraint indices were forecasted until 2030. They are 87.29 million t-CO₂, 0.45 t-CO₂/CNY10⁴ and 8.73 t-CO₂/person, respectively. The scale of urban land is controlled at 889.61; the constraint indices of residential, commercial service land, industrial land and road square land scales are 231.3 km², 143.88 km², 150.17 km² and 135.83 km², respectively. The land expansion intensity, urban compactness and shortest travel distance constraint indices are 6.19, 0.236 and 96,086.76 km, respectively. The results of this analysis can provide scientific guidance for the next step in territorial spatial master planning and low-carbon governance.

Global warming and the urban heat island (UHI) phenomenon have significant impacts on human activities, against which it is necessary to develop effective coping strategies. Based on the local climate zone (LCZ) system, this study used the land-cover and surface temperature data on the Chang–Zhu–Tan (CZT) urban agglomeration in China in 2006, 2010, 2016, and 2020 to analyze the impact of climate change on the land surface temperature (LST) under different land-cover types. The results illustrate that the LCZ map generated on the basis of the improved World Urban Database and Access Portal Tools (WUDAPT) is more accurate and efficient than the traditional method. The accuracy is increased by more than 15%. From 2006 to 2020, the main built-up types in the CZT urban agglomeration were the sparsely built, the large low-rise, and the compact mid-rise types. The low-plant type represents the most significant proportion of the natural types, followed by the water and the dense-tree types. The built-up types in the CZT urban agglomeration tend to be the high-rise, dense, and industrial types. Urban construction land is taken mainly from the sparsely built type of land. The average LST of the large low-rise and heavy-industry zones is significantly higher than the average LST of the three cities. The average LST values for the water and dense-tree zones are significantly lower than the other average LST values. The LST is stable in each LCZ, showing little correlation with the size of the LCZ area. Compact low-rise land use is ineffective against climate warming and inhibits economic growth. Compact high-rise and open high-rise land can not only effectively deal with climate warming but can also significantly stimulate economic growth. This paper helps us to understand the effect of land cover on climate warming and the economic benefits of LCZs in the CZT urban agglomeration and provides strategies to optimize the use of land resources.