统计与数据科学学院知识库

近年来，气候变暖的加剧在全球引发了一系列经济、社会和环境问题，已经严重威胁着人类的生存和可持续发展。作为世界第二大经济体和第一大碳排放国，虽然我国的国际影响力在不断增强，但是高碳排放也成为国际社会和舆论界关注的焦点。兰西城市群作为我国西部重要的跨省区城市群，是我国西部重要的生态屏障，也是黄河流域上游重要的工业和能源基地，对我国西部生态安全和经济社会发展具有重要的战略意义。

当前中国碳排放研究主要集中在国家、省域和经济较发达的地区，由于地级市及以下尺度能源消费统计数据缺失，导致对西部欠发达城市群碳排放的研究较少。因此，本文通过校正融合中国区域长时间序列DMSP/OLS与NPP/VIIRS夜间灯光影像，空间化模拟了1995-2019年兰西城市群的能源消费碳排放量；并从县级尺度视角出发，利用空间趋势分析、变异系数分析、探索性空间数据分析以及地理探测器等方法，对兰西城市群碳排放的时空分布特征、空间关联特征以及影响因素等问题进行研究。研究结果表明：

（1）从碳排放总量看，1995-2019年兰西城市群碳排放总量呈增长趋势，增长速度表现出明显的阶段特征，整体呈先上升后下降的趋势。碳排放量从1995年的36.23×10⁶t上升到2019年的116.61×10⁶t，增长了3.22倍；碳排放年平均增长速度为4.79%。从县域碳排放看，兰西城市群县域碳排放量增长明显，碳排放（10⁴t）区间由1995年的[13.4,425.4]增长为2019年的[103.2,1051.4]，最低的贵南县和最高的城关区分别增长8.46倍和2.47倍，碳排放量分别增长48.92×10⁴t和625.95×10⁴t。从碳排放强度看，兰西城市群绝大多数县区的碳排放强度呈持续下降的态势，碳排放强度（t/万元）区间由2005年的[4.2,9.7]下降为2019年的[1.6,5.0]。

（2）从时空分布看，1995-2019年，兰西城市群碳排放一直表现出东高西低，中部高、南北低的空间分布态势，高碳县区主要集中在人口密集、经济相对发达的兰州市和西宁市主城区；兰西城市群县域碳排放存在显著的空间差异性和正自相关性，但空间差异在不断缩小，空间正自相关性呈现出逐步扩大的趋势；兰西城市群县域碳排放的局部自相关比较稳定，主要表现为高-高聚集和低-低聚集，高-高聚集主要集中在兰州市主城区，低-低聚集分布在青海省黄南州和海南州。

（3）兰西城市群碳排放空间分异是多种因素综合作用的结果。其中，经济发展水平的作用力始终最强，财政支出、规模以上工业企业个数和产业结构也具有显著的作用力，人口密度、城镇化水平和能源强度的作用力相对较弱；影响因子经过两两交互以后，对碳排放空间分异的作用力显著增强，经济发展水平和规模以上工业企业个数分别与能源强度、产业结构、城镇化水平、人口密度所主导的交互作用是导致碳排放持续增长的主要推动力。

兰西城市群需协同发展，统筹规划，根据各县区资源环境承载力与国土空间规划，合理控制人口密度与城镇开发力度；在保持GDP持续增长的前提下，有必要对城镇化水平、能源强度、产业结构和财政支出等因素进行宏观调控，使其与关键因子之间的交互作用力得到削弱，从而使得碳排放增速持续放缓；同时，根据各县区碳排放的实际情况，制定精细化的碳减排政策，争取尽早达到碳峰值。

In recent years, the aggravation of global warming has caused a series of economic, social and environmental problems, which have seriously threatened the survival and sustainable development of mankind. As the world's second largest economy and the largest carbon emitter, Although China's international influence is increasing; its high carbon emissions have also become the focus of international community and public opinion circles. As an important inter-provincial urban agglomeration in the west of China, Lanzhou-Xining City agglomeration is an important ecological barrier in the west of China, as well as an important industrial and energy base in the upper reaches of the Yellow River Basin, which has important strategic significance for the ecological security and economic and social development in the west of China.

Currently, carbon emission studies in China are mainly focused on national, provincial and economically developed urban agglomerations. Due to the lack of statistical data on energy consumption at the prefecture-level and below,there are few studies on carbon emissions in the underdeveloped urban agglomeration in the west.Therefore, this paper spatially simulated the carbon emissions from energy consumption in the Lan-Xi urban agglomeration from 1995 to 2019 by combining long-term DMSP/OLS and NPP/VIIRS nighttime light images in China. From the perspective of county scale, spatial trend analysis, coefficient of variation analysis, exploratory spatial data analysis and geographic detector were used to study the spatial and temporal distribution characteristics, spatial correlation characteristics and influencing factors of carbon emissions in Lan-Xi urban agglomeration. The results show that:

(1) From the perspective of total carbon emissions, the total carbon emissions in the Lan-Xi urban agglomeration showed an increasing trend from 1995 to 2019, and the growth rate showed obvious stage characteristics, with an overall trend of rising first and then declining. Carbon emissions increased from 36.23×10⁶t in 1995 to 116.61×10⁶t in 2019, an increase of 3.22 times. The average annual growth rate of carbon emissions was 4.79%. From the point of view of county carbon emissions, the carbon emissions at the county level of Lan-Xi urban agglomeration increased significantly, with the range of carbon emissions (10⁴t) increasing from [13.4,425.4] in 1995 to [103.2,1051.4] in 2019. The lowest is Guinan county and the highest is Cheng’guan district which increased by 8.46 times and 2.47 times respectively. Carbon emissions increased by 48.92×10⁴t and 625.95×10⁴t respectively. From the perspective of carbon emission intensity, the carbon emission intensity of most counties and districts in The Lan-Xi urban agglomeration showed a trend of continuous decline, and the range of carbon emission intensity (t/10⁴ yuan) decreased from [4.2,9.7] in 2005 to [1.6,5.0] in 2019.

(2) From the perspective of spatial and temporal distribution, from 1995 to 2019, the carbon emission of Lan-Xi urban agglomeration showed a spatial distribution trend of high in the east and low in the west, high in the middle and low in the north and south. High-carbon counties are mainly concentrated in densely populated and relatively developed economies. There are significant spatial differences and positive autocorrelation of carbon emissions at county level in Lan-Xi urban agglomeration, but the spatial differences are narrowing, and the positive autocorrelation shows a trend of gradually expanding.The local autocorrelation of carbon emissions at county level in the Lan-Xi urban agglomeration was stable, dominated by high-high aggregation and low-low aggregation, and the high-high aggregation was mainly concentrated in the main urban area of Lanzhou, while the low-low aggregation was distributed in Huangnan prefecture and Hainan prefecture of Qinghai province.

(3) The spatial differentiation of carbon emissions in Lan-Xi urban agglomeration is influenced by multiple factors. The level of economic development always has the strongest influence on the spatial differentiation of carbon emissions. Fiscal expenditure, number of industrial enterprises above designated size and industrial structure also has significant influence on carbon emissions. The level of urbanization, population density and energy intensity have relatively weak influence on carbon emissions. After pair interaction, the influence of influencing factors is significantly enhanced compared with the explanatory power of any single influencing factor. The interaction of economic development level and number of industrial enterprises above designated size with energy intensity, industrial structure, urbanization level and population density is the main driving force leading to the continuous growth of carbon emissions.

Lan-Xi urban agglomeration should be coordinated development, overall planning, according to the resources and environment carrying capacity and territorial space planning of each county, reasonable control of population density and urban development intensity. On the premise of sustained GDP growth, it is necessary to carry out macro-control on industrial structure, energy intensity, urbanization level and fiscal expenditure, so as to weaken the interaction between them and the leading factors, thus slowing down the growth rate of carbon emissions. At the same time, according to the actual situation of carbon emissions in each county, formula Refined carbon emission reduction policies and strive to reach the carbon peak as soon as possible.