Evaluating the Effects of Climate Change on Thermal Bioclimatic Indices in a Tropical Region Using Climate Projections from the Bias-Corrected CMIP6 Model

As the global mean surface temperature continues to rise due to climate change, the impacts are not equally distributed worldwide, making regional assessments crucial. Bangladesh, a tropical monsoon region characterized by low-lying terrain, is particularly vulnerable to climate change effects. Yet, there has been a lack of analysis regarding potential shifts in thermal bioclimatic indicators (TBIs) in this region, a critical aspect of climate change adaptation. To address this gap, a study used a multimodel ensemble (MME) of 18 bias-corrected CMIP6 GCMs to project variations in 11 TBIs across Bangladesh for the near (2015–2044), mid (2045–2074), and far (2075–2100) futures under three SSPs: low (SSP126), medium (SSP245), and high (SSP585). By examining spatiotemporal changes in the ensemble mean, the study considered the base period (1985–2014) of each indicator for the respective future periods. The results of the study revealed that Bangladesh is likely to experience an increase in average annual temperature in the future, consistent with the global average. Depending on the SSP, the temperature rise could range from 0.62 to 1.85 °C for SSP126, 0.51–2.81 °C for SSP245, and 0.54–4.88 °C for SSP585. Furthermore, the study predicted a potential decrease in the diurnal temperature range (DTR) by − 0.17 to − 2.50 °C and a reduction of up to 30% in the ratio of mean diurnal temperature range to mean annual range. The projected temperature rise would vary significantly across regions, with the northeast and southeast experiencing increases between 0.14 and 0.39 °C, while the northwestern, central, and southwestern regions could see higher increases ranging from 0.17 to 2.66 °C. The study also highlighted a considerable increase in average temperature between the coldest and warmest quarters. Notably, the drier quarter would experience more substantial warming compared to the wettest quarter. These findings have important implications for climate change mitigation strategies in tropical monsoon regions like Bangladesh. Urgent action is needed to address the adverse consequences of global warming. Policymakers and stakeholders must understand these projected changes to implement measures that can reduce the impacts on agriculture, ecosystems, human health, and biodiversity. The study underscores the need to protect the well-being and sustainability of the nation in the face of a changing climate.