Examining global warming factors using self-organizing map and Granger causality network: a case from South Korea

Background Understanding and patterning the possible causal variables of global warming is attributed to the development of effective prevention and mitigation strategies for climate change. Therefore, we aimed to pattern and visualize the possible causal variables of global warming and measure the causality between them.Methods We patterned and visualized the time series（103 years, from 1918 to 2020） of global surface temperature（GTemp） data with the gross domestic product（GDP） per capita, human population（Pop）, and carbon dioxide（CO2）emissions of South Korea using a self-organizing map（SOM） and examined the causable local feature of global warming using the Granger causality（GC） test. The time-series data were trained and mapped in 4×4 SOM grids, and causality networks between variables were examined using multivariate Granger test statistics.Results SOM patterned 103 years of data, and a dominant cluster contained continuous time-series data from 2007 to 2020. Similarly, the CO2 emissions of South Korea were obtained as a predictable unidirectional causal variable for GTemp from GC analysis. Based on data from the past 34 years, significant causality（p-value = 0.01） was observed with the integrated effect of Pop, GDP, and CO2 on GTemp.Conclusion This study patterned the time-series data using SOM and examined the causal relationship between variables using the GC test. The study framework could be used as a reference by future scholars, ecologists, and the United Nations Sustainable Development Goals.