Carbon dioxide emissions peaks depend on changes in economic scale and industrial structure

Reaching carbon dioxide (CO2) emissions peak is a prerequisite for achieving carbon neutrality. Most developing countries are puzzled about how to achieve CO2 emissions peak, whereas other countries are uncertain whether the recent inflection points in CO2 emissions represent genuine peaks. In this study, we identified the decisive factors and numerical ranges for peaking CO2 emissions from a socioeconomic development perspective, and we further established the criteria for distinguishing between genuine and spurious CO2 emissions peaks. By employing principal component analysis and the panel threshold regression model, in this study, we investigated the nonlinear dynamic impacts of socioeconomic factors on CO2 emissions in 16 developed countries with peak emissions during the period from 1960 to 2016. The results demonstrate that a nonlinear threshold effect is exerted by the economic subsystem, characterized by economic scale and industrial structure, on CO2 emissions, thus playing a predominant role in the peaking process of CO2 emissions by shaping both the total amount and the timing of reaching the peak, and emerging as the key factor in distinguishing between genuine and spurious CO2 emissions peaks. The identified criteria for this distinction are as follows: a gross domestic product (GDP) growth rate of between 1.20 % and 4.94 %, a GDP per capita ranging from USD 18,519 to USD 44,597, and the ratio of tertiary industry output value to the total GDP falling within 51–65 %. All three key indicators must be simultaneously satisfied to fulfill the criteria to achieve a genuine CO2 emissions peak. The findings of this study not only facilitate the scientific and precise identification of the CO2 emissions peak but also provide invaluable references for countries or regions that have not yet reached their peaks in formulating and refining economic development strategies to achieve CO2 emissions peak.