According to the conventional economic approach, global warming and climate change are analyzed based on externality in light of the benefit-cost principle. The problem is formulated as the relationship between marginal private benefit-cost and marginal social benefit-cost. Despite this relatively straightforward and theoretically understandable conventional formulation, global warming and climate change differ from other environmental problems previously encountered locally. For example, the distinction between greenhouse gas emissions (a flow variable) and greenhouse gas concentrations (a stock variable) is neglected in this economic analysis. Additionally, this fundamental economic analysis assumes that the damage caused by emissions is independent of time and emission source and that emissions have no effects outside the analyzed economy. Such difficulties inherent in global warming and climate change make determining the difference between private marginal benefit-cost and social marginal benefit-cost difficult, as well as expressing it monetarily.

Unlike the difficulties of economic analysis, a physical and ecological approach to the problem provides a clearer picture of what is happening to the target of mitigation. According to this approach, the social, economic, and ecological damage resulting from climate change are a positive function of human-induced greenhouse gas emissions and of the vulnerabilities of social and ecological systems toward climate change. If the aim is to solve the problem, either the thermal balance of the earth should be ensured by reducing the greenhouse gas emissions to a level compatible with natural cycles, or the fragility of social and ecological systems against climate change should be reduced. As a result of this formulation, the only rational solution to climate change is to reduce anthropogenic greenhouse gas emissions. The Impact = Population x Affluence x Technology (IPAT) identity used to express human activities’ effects on the environment shows population, economic activity, and energy consumption to be the most critical variables determining human-induced greenhouse gas emissions. Accordingly, population growth, economic growth, greenhouse gas intensity of the energy system, and the economy are the most essential variables to focus on to reduce and break the link between human activities and greenhouse gas emissions.

Leaving the economic analysis difficulties aside and focusing on environmental impact variables, the picture regarding global warming and climate change is quite clear. In order to reduce human-induced greenhouse gas emissions, the energy efficiency of the economy must be increased, and a fundamental and rapid transformation must be carried out that results in a reduction of carbon intensity within the energy system. The environmental impact analysis shows fossil fuel-based economic growth to be the most critical problem to overcome in reducing greenhouse gas emissions. While significant gains have been made in reducing energy system-related carbon emissions thanks to the decrease in the energy intensity of the economy, as long as the energy system remains dependent on fossil fuels and continues to release carbon dioxide into the atmosphere, no net decrease will ever occur in the amount of carbon dioxide emissions. In addition, although global warming and climate change were initially formulated as a carbon problem caused by fossil fuels, the amount of energy use and emissions are not independent of per capita income, consumption, and welfare level.

This study aims to analyze G20 members using two basic cluster analysis methods based on different emission criteria. For this purpose, per capita greenhouse gas emissions, per capita income, per capita electricity consumption, emission intensity of electricity production, emission intensity of primary energy supply, and emission intensity of the economy have been selected. The study uses the k-means cluster and hierarchical cluster analysis methods within the program R. In R, the get_dist and fviz_dist functions within the factoextra package are used to calculate and visualize the distance matrix from the R packages.

The presence of more than one greenhouse gas with different sources and sinks that play a role in global warming poses a significant problem in density calculations based on greenhouse gases. Although global warming and climate change were initially formulated as a carbon problem caused by fossil fuels, energy use and emissions are not independent of per capita income, consumption, and welfare. To this end, the analysis has also included the other greenhouse gases. The first three variables are expressed at the per capita level. These variables can be seen as scale variables that determine total greenhouse gas emissions.

Meanwhile, the last three variables, which should be considered technological variables, are intensity variables expressed at the unit activity level. Although the emissions of developing countries are close to developed countries in terms of the scale variables, differences occur between developing and developed member countries in terms of technological variables and different clusters.