Regression estimates: Double threshold model.

Despite having barely anything to do with the issue of CO2 emissions, Africa has been experiencing more severe climate change and its adverse effects than most other regions of the globe. However, the issue of CO2 emissions and its adverse effects has received relatively little attention in the African research arena. To this end, the present research assesses the effect of trade openness on the CO2 emissions utilizing panel data from 46 African countries spanning 2000 through 2022. To account for the possible heterogeneity and nonlinearity, the panel quantile regression and threshold methods were employed. Moreover, this study investigates the key mediating effects of the channel. The empirical findings show that greater trade openness is associated with significantly higher CO2 emission, additionally; it demonstrates that the influence is heterogeneous across different CO2 emission quantiles in African countries. Besides the result from the double threshold model reveals a complex, nonlinear relationship between trade openness and CO2 emissions in Africa. Moreover, the findings divulge that openness to trade indirectly reduces CO2 emissions through the substitution and technology channels whereas it indirectly increases carbon dioxide production via the economic track. Therefore, it is vital to promote the use of renewable energy, effectively leverage the knowledge spillover effects of trade to decrease energy intensity and formulate pertinent policies aimed at curbing carbon emissions and addressing the imminent threat of climate change in Africa. Besides, the nonlinear and heterogeneous effects of trade openness on CO2 emissions suggest that policies and interventions related to the impact of trade openness on CO2 emissions should consider the current level of carbon dioxide emissions.尽管非洲几乎与二氧化碳（CO₂）排放议题毫无关联，却比全球绝大多数地区承受了更为严峻的气候变化及其负面影响。然而，二氧化碳排放及其负面影响在非洲研究领域却相对乏人问津。鉴此，本研究采用2000年至2022年46个非洲国家的面板数据，评估贸易开放度对二氧化碳排放的影响。为考量潜在的异质性与非线性特征，本研究运用面板分位数回归与门槛模型方法。此外，本研究还探讨了该影响的关键中介渠道。实证结果显示，更高的贸易开放度与显著更高的二氧化碳排放水平显著相关；同时，该影响在非洲各国不同二氧化碳排放分位点上呈现异质性特征。双重门槛模型的结果进一步揭示，非洲地区贸易开放度与二氧化碳排放之间存在复杂的非线性关系。研究结果还表明，贸易开放度通过替代效应与技术渠道间接降低二氧化碳排放，却通过经济增长路径间接推高二氧化碳产出。因此，推广可再生能源使用、有效利用贸易的知识溢出效应以降低能源强度，并制定针对性政策以遏制碳排放、应对非洲迫在眉睫的气候变化威胁，至关重要。此外，贸易开放度对二氧化碳排放的非线性与异质性影响提示，与贸易开放度对碳排放影响相关的政策与干预措施，应结合当前的二氧化碳排放水平制定。