*3.4. Estimation of the Future Green Development Level of the Chengdu-Chongqing City Group under the SSPs*

3.4.1. Analysis of Changes in Green Development Levels in the Chengdu-Chongqing City Group

The abovementioned model parameters of each city in the Chengdu-Chongqing City Group were included in the SD model; the values of the various socio-economic indicators from 2019 to 2050 were simulated, and the entropy weight method was applied to calculate the green development level and criterion level of each city under the five SSPs considered, to further analyze the changes in the green development level in the Chengdu-Chongqing City Group. The simulation results are shown in Figure 7.

Under the five SSPs, the green development level and the guideline level of each city in the Chengdu-Chongqing City Group will increase overall. Specifically, the green development level of Chengdu and Chongqing will be significantly higher than that of other cities in the Chengdu-Chongqing City Group, and the gap will tend to further widen. Mianyang ranked third for green development level, showing a clear advantage over the other cities in 2022–2035. However, the gap between the green development level of Leshan and Mianyang is projected to gradually narrow, while that of Dazhou will be the lowest among all the cities investigated. In general, the green development level and the guideline level of each city will have different development growth rates and coordination levels under different pathways.

Under SSP1, the green development level of each city will have the fastest growth among all pathways considered; this growth is also expected to be coordinated and stable, although the gap between Dazhou and other cities will further expand.

Under SSP2, the cities were divided into four echelons according to their level of green development. Chengdu and Chongqing are in the first echelon and are characterized by similar levels of green development; the second echelon includes the cities of Mianyang and Leshan, the latter being expected to have almost the same level of green development as Mianyang by 2050. The fourth echelon includes only the city of Dazhou, and its gap with the other cities is projected to further expand. The other cities are in the third tier.

Under SSP3, the growth rate of the green development level will be the slowest among all the pathways considered; Chengdu and Chongqing will maintain the lead, with a large gap between them and the rest of the cities. Dazhou will have the lowest level of green development, although the gap between it and the other cities will first widen and then narrow.

Under SSP4, the growth rate of the green development level of each city will be stable overall, with a slowdown and a small plateau period appearing from 2030 to 2040, after which the growth will accelerate. Chengdu and Chongqing will have significantly higher levels of green development than the other cities, although this gap will first increase and then decrease. Mianyang and Leshan will follow in the ranking, and the gap between them will tend to shrink continuously until 2050, when it is expected to almost disappear.

Under SSP5, the green development level of each city will increase steadily, with Chengdu and Chongqing recording an almost equal level. Compared to other paths, the gap between Chengdu and Chongqing and the other cities will be the smallest, while the gap between Dazhou and the other cities will be the largest and will tend to expand continuously.

Looking at these results from the perspective of each city in the Chengdu-Chongqing City Group, it can be seen that the green development level of each city under SSP1 will be the highest and will have an overall steady growth trend; Chengdu will maintain the leading position, followed by Chongqing, and the gap between the remaining cities will tend to be stable. Under SSP3, all the cities in the Chengdu-Chongqing City Group will have the lowest level of green development and the slowest growth rate; moreover, the trend of growth will be uneven, with Chengdu and Chongqing expected to have a significantly higher growth trend than the other cities.

**Figure 7.** *Cont*.

**Figure 7.** *Cont*.

third tier.

then narrow.

**Figure 7.** The green development level and the guideline level of each city in the future under 5 SSPs paths: (**a**) SSP1, (**b**) SSP2, (**c**) SSP3, (**d**) SSP4, (**e**) SSP5. **Figure 7.** The green development level and the guideline level of each city in the future under 5 SSPs paths: (**a**) SSP1, (**b**) SSP2, (**c**) SSP3, (**d**) SSP4, (**e**) SSP5.

Under the five SSPs, the green development level and the guideline level of each city in the Chengdu-Chongqing City Group will increase overall. Specifically, the green de-3.4.2. Analysis of the Overall Future Green Development Level of the Chengdu-Chongqing City Group

velopment level of Chengdu and Chongqing will be significantly higher than that of other cities in the Chengdu-Chongqing City Group, and the gap will tend to further widen. Mianyang ranked third for green development level, showing a clear advantage over the Based on the analysis of the future green development level of each city in the Chengdu-Chongqing City Group and the level of the criterion layer under the SSPs, the future green development level of the Chengdu-Chongqing City Group as a whole was calculated; it is shown in Figure 8.

other cities in 2022–2035. However, the gap between the green development level of Leshan and Mianyang is projected to gradually narrow, while that of Dazhou will be the lowest among all the cities investigated. In general, the green development level and the guideline level of each city will have different development growth rates and coordination levels under different pathways. Under SSP1, the green development level of each city will have the fastest growth among all pathways considered; this growth is also expected to be coordinated and stable, although the gap between Dazhou and other cities will further expand. Under SSP2, the cities were divided into four echelons according to their level of green development. Chengdu and Chongqing are in the first echelon and are characterized by similar levels of green development; the second echelon includes the cities of Mianyang and Leshan, the latter being expected to have almost the same level of green development as Mianyang by 2050. The fourth echelon includes only the city of Dazhou, and its gap with the other cities is projected to further expand. The other cities are in the From Figure 8, it can be seen that the future green development level and the guideline level of the Chengdu-Chongqing City Group as a whole will have a rising trend in all SSPs, and the growth rate will gradually decrease. In terms of green development, its level will be the highest under SSP1 and the lowest under SSP3, in which its growth rate will also be the slowest among all the SSPs considered. Moreover, the gap among the green development levels of SSP2, SSP4, and SSP5 will be narrow until 2035, with the highest level in SSP4 and the lowest in SSP2; after 2035, the growth rate under SSP4 will slow down and will be surpassed by that of SSP5, such that the level of green development under the latter will exceed that of the former and will be second only to SSP1. In terms of the socio-economic level of the Chengdu-Chongqing City Group, this will be the highest under SSP5, followed by SSP1, and it will be the lowest under SSP3. In terms of the resource and environment level, this will be the highest under SSP1 and the lowest under SSP3 and SSP5, with a small difference between the latter two. In terms of the quality-of-life level, this will be the highest under SSP1 and the lowest under SSP3. Moreover, under SSP4 it will be second only to SSP1 until 2039, after which that under SSP5 will grow relatively fast and will surpass SSP4.

Under SSP3, the growth rate of the green development level will be the slowest among all the pathways considered; Chengdu and Chongqing will maintain the lead, with a large gap between them and the rest of the cities. Dazhou will have the lowest level of green development, although the gap between it and the other cities will first widen and

Under SSP4, the growth rate of the green development level of each city will be stable overall, with a slowdown and a small plateau period appearing from 2030 to 2040, after tinuously.

qing City Group

calculated; it is shown in Figure 8.

icantly higher growth trend than the other cities.

which the growth will accelerate. Chengdu and Chongqing will have significantly higher levels of green development than the other cities, although this gap will first increase and then decrease. Mianyang and Leshan will follow in the ranking, and the gap between them will tend to shrink continuously until 2050, when it is expected to almost disappear. Under SSP5, the green development level of each city will increase steadily, with Chengdu and Chongqing recording an almost equal level. Compared to other paths, the gap between Chengdu and Chongqing and the other cities will be the smallest, while the gap between Dazhou and the other cities will be the largest and will tend to expand con-

Looking at these results from the perspective of each city in the Chengdu-Chongqing City Group, it can be seen that the green development level of each city under SSP1 will be the highest and will have an overall steady growth trend; Chengdu will maintain the leading position, followed by Chongqing, and the gap between the remaining cities will tend to be stable. Under SSP3, all the cities in the Chengdu-Chongqing City Group will have the lowest level of green development and the slowest growth rate; moreover, the trend of growth will be uneven, with Chengdu and Chongqing expected to have a signif-

3.4.2. Analysis of the Overall Future Green Development Level of the Chengdu-Chong-

Based on the analysis of the future green development level of each city in the Chengdu-Chongqing City Group and the level of the criterion layer under the SSPs, the future green development level of the Chengdu-Chongqing City Group as a whole was

**Figure 8.** The overall green development level and criteria level of the Chengdu-Chongqing City Group based on SSP paths. **Figure 8.** The overall green development level and criteria level of the Chengdu-Chongqing City Group based on SSP paths.

From Figure 8, it can be seen that the future green development level and the guideline level of the Chengdu-Chongqing City Group as a whole will have a rising trend in all SSPs, and the growth rate will gradually decrease. In terms of green development, its level will be the highest under SSP1 and the lowest under SSP3, in which its growth rate will also be the slowest among all the SSPs considered. Moreover, the gap among the green From the perspective of individual paths, the green development level, the resource and environment level, and the quality-of-life level of the Chengdu-Chongqing City Group under SSP1 will be the highest, and their growth rate will also be the highest. The green development level will rise relatively steadily, increasing by 1.62 times by 2050, with an average annual growth rate of about 1.7%. The level of resources and environment will increase by 1.1 times until 2035, with an average annual growth rate of 0.63%; from 2035 to 2050, the growth rate will slightly accelerate, increasing by 1.14 times, with an average annual growth rate of about 0.93%. The development advantage of the level of resources and environment will become increasingly evident under SSP1, and the gap with the other paths will gradually increase. The socio-economic level of the Chengdu-Chongqing City Group under the SSP1 path will be second only to that of SSP5 and will be characterized by an increase of 1.56 times by 2050 and an average annual growth rate of about 1.6%.

Under SSP2, the green development level of the Chengdu-Chongqing City Group ranks fourth, with an increase of 1.5 times by 2050 and an average annual growth rate of about 1.5%. Under this pathway, the socio-economic level ranks fourth with an average annual growth rate of about 2.0% until 2041, after which SSP2 will overtake SSP4 and rank third, with an average annual growth rate of about 0.6% from 2041 to 2050.Under SSP2, the resource and environment level will be basically the same as that of SSP4 until 2026; after 2026, it will rank second after SSP1 and will increase by 1.2 times until 2050, with an average annual growth rate of 0.66%. In this pathway, the quality-of-life level will be similar to that under SSP5 until 2030, after which a gap will open up, and it will gradually lag behind SSP5, ranking fourth, with an increase of 1.9 times by 2050 and an average annual growth rate of about 2.3%.

The green development level and the guideline level of the Chengdu-Chongqing City Group under SSP3 will be the lowest, and the growth rate will be relatively slow and will tend to stabilize. Under this pathway, the green development level will increase by 1.34 times until 2050, with an average annual growth rate of about 0.99%. The socioeconomic level will grow by 1.35 times by 2050, with an average annual growth rate of

about 1.1%. Moreover, the resource and environment level will be only slightly lower than in SSP5; it will increase by about 1.1 times by 2050, with an average annual growth rate of about 0.44%. The quality-of-life level will increase by about 1.5 times by 2050, with an average annual growth rate of about 1.5%.

The green development level and the guideline level of the Chengdu-Chongqing City Group under SSP4 will be at an average level. The former will rank second after SSP1 until 2030; after 2030, it will be surpassed by that of SSP5 and will, thus, rank third; after 2042, it will be very close to that of SSP2 and will be equal to 0.46 in 2042. Overall, from 2022 to 2050, the green development level under SSP4 will increase by 1.5 times, with an average annual growth rate of about 1.46%. Under this pathway, the socio-economic level will be very close to that of SSP1 and SSP5 until 2030, after which it will gradually diverge, ranking third until 2041. After that, it will be slightly surpassed by that of SSP2, ranking fourth, with an average annual growth rate of about 1.39% until 2050. The quality-of-life level under SSP4 will rank second after SSP1 until 2040, after which it will be overtaken by that of SSP5 and will rank third, with an increase of 1.9 times by 2050 and an average annual growth rate of 2.4%.

The green development level, the socio-economic level, and the quality-of-life level of the Chengdu-Chongqing City Group under SSP5 will be the highest among all the pathways considered, while the resource and environment level will be the lowest. Under this pathway, the green development level will rank third until 2030, after which it will overtake SSP4 to rank second, increasing from 0.33 in 2022 to 0.53 in 2050, with an increase of 1.61 times and an average annual growth rate of about 1.69%. The socio-economic level will always be the highest, and its gap with that of the other pathways will widen, growing by 1.67 times by 2050, with an average annual growth rate of about 1.92%, i.e., the fastest growth rate among the five SSPs. Moreover, the resource and environment level under SSP5 will be almost the same as that in SSP3 and will be the lowest among the five SSPs considered, although it will slowly increase by 1.12 times by 2050. The quality-of-life level under SSP5 will rank third until 2039, after which it will overtake SSP4 to rank second, right after the SSP1 path, and will increase by 2.1 times by 2050, with an average annual growth rate of 2.68%.

#### *3.5. Suggestions for the Future Development Path of the Chengdu-Chongqing City Group*

The comparative analysis of the green development level of the Chengdu-Chongqing City Group as a whole and for each city under the shared SSPs considered, showed that under SSP1 both the green development level and its growth rate will be the highest among all the SSPs. Moreover, the green development level of the Chengdu-Chongqing City Group under SSP2 will be very similar to that under SSP4 and SSP5 before 2025, and will be lower only than that under SSP1. The year 2025 is the closing year of China's 14th Five-Year Plan, which calls for the promotion of green development and the acceleration of the green transformation of the development methods. The period of 2025–2035 will be key for China to achieve a full modernization; moreover, the peak of carbon emissions is set to be reached before 2030, after which the steady decrease in carbon emissions will contribute to the achievement of the goal of building a beautiful China. Therefore, the transition from SSP2 to SSP1 should be completed by 2035 to achieve real sustainable development, and the latter pathway should be steadily followed from 2035 to 2050 so as to achieve carbon neutrality by 2060.

From the socio-economic point of view, the economic development of the Chengdu-Chongqing City Group will remain very uncoordinated and "polarized" for a long time in the future. The economic development level of Chengdu and Chongqing is far ahead of that of the other cities; the fundamental reason is that the regional GDP and the degree of openness of the other cities are relatively low, and the total import and export amount of Dazhou and Ya'an is only about 1% of that of Chengdu and Chongqing. Hence, it is important to narrow the economic differences among the cities in the Chengdu and Chongqing City Group to improve the overall green development level.

From the point of view of resources and environment, the resource and environment condition of the Chengdu-Chongqing City Group will not greatly improve in the future, which is in line with its development status; moreover, resource consumption and environmental pollution will increase together with the economic development. At present, the proportion of secondary industries in the Chengdu-Chongqing urban agglomeration is still very high, with more than 50% of the cities accounting for more than 45% of the secondary industries. The high energy consumption and pollution emissions of traditional heavy industries are the key factors hindering the green growth of the entire Chengdu-Chongqing City Group.

In terms of quality of life, the quality-of-life level of all the cities will steadily increase, although that of Dazhou will be considerably lower compared to the other cities. Although the population of Dazhou is gradually declining, its total population is higher than that of Mianyang, the second largest city in Sichuan, and its population pressure is also high. Accordingly, the resources at the disposal of each individual, such as medical care, roads, and green areas, are also relatively small.
