城市土地经济密度与碳排放的EKC假说与验证——基于省际静态与动态面板数据的对比分析

Hypothesis and Validation on the Environmental Kuznets Curve Relation Between Urban Land Economic Density and Carbon Emissions: A Comparative Analysis of Static Panel Data and Dynamic Panel Data

在土地利用和碳排放方面的环境库兹涅茨曲线假说研究基础上,提出城市土地经济密度与碳排放之间的EKC假说。基于1995—2012年中国省际面板数据,分别构造静态面板模型和动态面板模型对假说进行验证。静态模型和动态模型估计结果均表明,城市土地经济密度与碳排放之间存在EKC的"重组"效应,二者呈现倒N型的曲线关系,曲线的极大值点出现在城市土地经济密度为180000万元/km2附近。动态模型估计的结果也表明碳排放具有明显的滞后效应。当前,除上海、浙江、福建、河北和江苏5个省(市)的城市碳排放量随着城市土地经济密度增长而降低外,大部分地区的城市需到2020年才能进入这一阶段。为此,要提升城市土地经济密度使城市尽早进入曲线的下降阶段,以及提高生产技术水平促使极大值点提前到来。

According to the EKC theory and resent research of EKC hypothesis on land use and carbon emissions,this paper put forward a hypothesis that there is an Environment Kuznets Curve( EKC) relation between urban land economic density and carbon emissions in China,which shows an inverted U-shape curve. The paper built a static panel data model and a dynamic panel data model respectively to validate the hypothesis. Both the estimated result of static model and that of dynamic model show that the relation between urban land economic density and carbon emissions does not match the EKC relation completely,which shows an inverted N-shape curve. Carbon emissions reduce as urban land economic density grows at first,then both carbon emissions and urban land economic density grow together,and carbon emissions reduce again once the density reaches a turning point. Besides,the estimated result of the dynamic panel model shows that an significant delayed effect exists in carbon emissions. Furthermore,the paper simulated a static cubic curve and a dynamic cubic curve. Compare with them,the static cubic curve'minimum point appears earlier than dynamic cubic curve's,while the static cubic curve's maximum point appears later than dynamic one 's. The maximum point appears when urban land density comes to around 1. 8 billion yuan per square kilometres. Currently,carbon emissions in Shanghai,Zhejing,Fujian,Hebei and Jiangsu go down as their urban land economic density grows,but most of cities' carbon emissions and urban land economic density increase synchronously. The situation may not be changed until 2020. Nowadays,China is facing a tough situation of carbon emissions control. Chinese government should control the irrational expansion of urban land,improve urban land use situation and increase land intensive use level,improve production technology level,readjust urban industrial structure and optimize energy consumption structure to urge cities to enter into the decline phase of EKC as early as possible.