Temporal-Spatial Patterns Of Land Use Carbon Emissions And Low Carbon Optimization In Chongqing In Recent 20 Years

Since the middle of the 20th century,the concentration of CO₂ in the atmosphere had been continuously increased,due to the influence of human activities and it became the main factor causing global changes.As the largest developing country in the world,China had huge energy demand and consumption,therefore it was particularly important for China to achieve low carbon emission reduction targets.Change of land use was an important factor which was affecting global change and carbon cycle.Various human energy consumption and industrial activities that brought a lot of carbon emissions were closely related to land use patterns and their intensity.Therefore,one of the effective ways to develop low-carbon economy goals was to strengthen land use management and macro-control.Therefore,under the background of the new normal of economy,it was urgent that the low-carbon land use could be realized through the adjustment and optimization of land use.By doing that,it was naturally that we could realize the sustainable development of regional economic and social development in Chongqing.In order to do this,the research was based on county scale,focusing on the main line of“space-time difference-influencing factors-optimization policies”,and it was from the perspective of low carbonization and based on an analysis of the temporal and spatial changes in land use in the city over the past20 years.By constructing a land use carbon emission estimation model,the research analyzed carbon emission effects of land use in the city.It revealed the spatial and temporal differences of land use carbon emissions in the city and the factors affecting land use carbon emissions in the city.The study optimized the city's land use structure with low carbon emission reduction and explored the city's land use optimization allocation policy system.Thereby it provided policy basis and decision support for the development of low-carbon economy and ecological civilization.The main findings are as follows:?1?The spatial and temporal changes of land use in Chongqing during the period1997-2015 were analyzed.In terms of the amount of land use,such as the city's garden land,forest land,urban and rural construction land,transportation land,water area increased,reduced area of cultivated land,pasture,other agricultural land,natural reserves,etc.The area was decreased.In terms of land use structure,the proportion of agricultural land area in the city increased,the proportion of construction land increased significantly,the proportion of other land was significantly lower.In terms of land use efficiency,the city's economic,social and ecological benefits were greatly improved.The GDP per capita has increased from 1,846,900 yuan per square kilometer to 18.1157 million yuan per square kilometer,the population density has increased from 376 people per square kilometer to 409 people per square kilometers,forest coverage increased from 36.14%to 46.22%.In the four districts of Chongqing?main city,one circle area,southeastern of Chongqing area,northeastern of Chongqing area?,corresponding changes have also taken place in terms of land use quantity,land use structure and land use efficiency.?2?The study revealed the spatial and temporal differences in land use carbon emissions in Chongqing during the period 1997-2015.The city's land use carbon emissions showed a continuous growth trend,and the total carbon emissions increased from 10.1006 million tons in 1997 to 24.4315 million tons in 2015,and it was a certain stage.Affected by the complex topographical landforms and differences in urban and rural economic and social development,the heavy land use carbon emissions were mainly concentrated in the core area of the main city,the medium and light emissions were mainly concentrated in the main city expansion area,the main urban area and the regional central city,the emissions were mainly concentrated in the Wuling Mountain Area in southeastern of Chongqing and the Three Gorges Reservoir Area in northeastern of Chongqing.The spatial correlation of land use carbon emission in the whole city was strong overall,and the global spatial autocorrelation Moran's I value first decreased and then increased,but it was generally in a state of agglomeration and presented a high value agglomeration state.The local spatial autocorrelation showed that the high-value agglomeration area of land use carbon emission was mainly located in the main urban area and the main urban area,and the low-value agglomeration area was mainly located in the southeastern part of Chongqing and northeastern of Chongqing,forming a low-value isolated area in the main urban area.The main factors affecting land use carbon emissions at the county level in Chongqing included the total energy consumption,per capita GDP,and urbanization rate.In addition,factors such as the total population,the proportion of secondary and tertiary industries,and the proportion of construction land also affected the carbon emission level of land use.?3?The influencing factors of land use carbon emissions in Chongqing during1997-2015 were clarified.The effects of various decomposition factors on the change in carbon emissions showed volatility.Influenced by family planning,social and economic development and other related policies,population size effects had less impact on carbon emissions.With the continuous improvement of per capita GDP,the impact of economic development on carbon emissions was more obvious.At the same time,under the trend of declining energy consumption per unit of GDP in the city,the energy consumption intensity had a significant inhibitory effect on carbon emissions;while the energy structure intensity showed a significant lag.The decomposition factors of carbon emissions in various regions showed spatial and temporal differences.During the period 2000-2005,the population size effect of the northeastern characteristic industrial zone and the northeastern characteristic agricultural product zone had the most obvious impact on carbon emissions.In the two stages of 2005-2010and 2010-2015,the population size effect had little impact on carbon emissions.It was also affected by policies such as industrial transformation and upgrading,energy structure adjustment,energy conservation and emission reduction,and the economic development effects and energy consumption intensity of each region.And the strength of the energy structure showed volatility.?4?The study optimized the regional land use structure of Chongqing City with the goal of low carbonization.According to the minimization of land use carbon emissions,the city's arable land area was 1906,000 hectares,the garden area was296,933.0 hectares,the forest land area was 4,262,852 hectares,the grassland area was88,497.12 hectares,the construction land area was 659,786.2 hectares,the water area was 182,614.1 hectares,and the unused land area was 840,996.3 hectares.The total amount of emissions was 68,667,660t.According to the maximization of ecosystem carbon storage,the city's cultivated land area was 1,906,000 hectares,the garden area was 544,035.2 hectares,the forest land area was 4,015,480 hectares,the grassland area was 88,497.12 hectares,the construction land area was 659,786.2 hectares,the water area was 182,614.1 hectares,and the unused land area was 840,996.3 hectares.The total accumulation was 1,186,271,897 tons.At the same time,the optimization of low-carbon utilization structure of regional land was carried out in 38 districts and counties,and the policy recommendations for regional low-carbon utilization differentiation were proposed.