Second generation unit root test.

This study examines how various environmental and economic variables contribute to environmental degradation. Industrialization, trade openness, and foreign direct investment are among the variables, as are environmental diplomacy, environmental diplomacy secure, and renewable energy consumption. Therefore, the data covers the years 1991–2020, and our sample includes all 19 countries and two groups (the European Union and the African Union). The research used the Pesaran CD test to determine cross-section dependency, CIPS and CADF test to determine stationarity, the Wald test for hetrodcedasasticity and the Wooldridge test for autocorrelation; therefore, VIF for multicollinearity, Durbin and Hausman to analyze the endogeneity. It also employed Westerlund’s cointegration test to ensure cross-sectional dependence, Wald test for group-wise heteroscedasticity, Wooldridge test for autocorrelation, VIF for multicollinearity, and Durbin and Hausman for endogeneity. The two-step system generalized method of moments (GMM) is used to estimate the results and confirm the relationship between independent variables (Industrialization, trade openness, FDI, environmental diplomacy, secure environmental diplomacy, and renewable energy) and dependent variables (Environmental Degradation) in G20 countries. Therefore, Industrialization, trade openness, foreign direct investment, ecological diplomacy, and renewable energy consumption significantly impact ecological degradation. Environmental diplomacy is crucial to combat degradation and stimulate global collaboration. G20 nations enact strict environmental restrictions to tackle climate change and encourage economic growth.

本研究旨在探讨各类环境与经济变量对环境退化的驱动作用。所纳入的解释变量涵盖工业化、贸易开放度、外商直接投资（Foreign Direct Investment, FDI）、环境外交、安全型环境外交以及可再生能源消费。据此，本研究的数据覆盖1991—2020年，样本包含19个国家以及两个区域集团——欧洲联盟（European Union）与非洲联盟（African Union）。

研究方法层面，本研究采用佩萨兰CD检验（Pesaran CD test）判断截面相关性，运用CIPS检验与CADF检验确定序列平稳性，借助沃尔德检验诊断异方差性、伍德里奇检验（Wooldridge test）分析自相关问题，通过方差膨胀因子（VIF）检验多重共线性，并使用杜宾检验与豪斯曼检验分析内生性。此外，本研究还运用了韦斯特伦德协整检验（Westerlund’s cointegration test）以验证截面相关性，并重复开展了分组异方差沃尔德检验、自相关伍德里奇检验、多重共线性方差膨胀因子检验以及内生性杜宾与豪斯曼检验。

本研究采用两步系统广义矩估计（Generalized Method of Moments, GMM）进行参数估计，以验证二十国集团（Group of Twenty, G20）成员国中各解释变量（工业化、贸易开放度、外商直接投资、环境外交、安全型环境外交与可再生能源消费）与被解释变量（环境退化）之间的关联。

实证结果显示，工业化、贸易开放度、外商直接投资、环境外交以及可再生能源消费对环境退化具有显著影响。环境外交对于遏制环境退化、推动全球协同合作至关重要。二十国集团成员国通过制定严格的环境规制以应对气候变化并促进经济增长。