Exploring environmental and meteorological factors influencing greenhouse gas emissions on major urbanized cities in Bangladesh

Abstract

The greenhouse effect, which leads to global warming and climate change, is a significant concern for developing countries like Bangladesh due to its direct and substantial impacts on various sectors of society and the economy. This study focuses on greenhouse gases (GHGs) like methane (CH₄), ozone (O₃), and water vapor (WV) and their trend patterns across the four most industrialized cities in Bangladesh. For this purpose, twelve environmental and meteorological variables with 60 months of data (2019–2023), known to influence GHG emissions, were selected as predictors. A Generalized Additive Model (GAM) and Principal Component Analysis (PCA) were used to assess the relationships and predictor influence on GHGs. The results reveal a consistent seasonal pattern in the GHGs identified over the observed years. The results of GAM show that population density (PD) demonstrates a robust correlation with CH₄ across all cities, yielding high linear correlations: R² = 0.93 for Dhaka, 0.85 for Khulna, and cubic R² = 0.87 for Rajshahi, all statistically significant (P = 0.00). Conversely, in Chittagong, municipal solid waste (MSW)/day exhibits a strong cubic correlation with CH₄ (R² = 0.95, P = 0.002). Moreover, O₃ and WV show proportional relationships with temperature and precipitation and also being statistically significant in all cities (p < 0.05). Notably, Dhaka exhibited the highest intercept for CH₄, while Rajshahi showed the highest for O₃ and WV. Key predictors included temperature and PD for O₃; PD, MSW, and albedo for CH₄; and precipitation and PD for WV in most of the cities. In the PCA analysis, PC1 is primarily associated with climatic factors, while PC2 reflects anthropogenic and land-use factors. PCA-regression shows the modest predictive power of the model for O₃ and WV. This study provides critical city-specific insights into GHG emissions and their determinants, offering valuable guidance for policymakers and planners to formulate effective emission management strategies.