Thermal Bioclimatic Transformations in the Coastal Regions of Ganges Delta: Insights from CMIP6 Multi-Model Ensembles

Abstract

The effects of climatic alteration caused by global warming on people, the environment, and ecosystems can be better understood by examining thermal bioclimatic indicators (TBIs) changes. Evaluating such alterations is of utmost significance for the Ganges Delta (GD) coastal region, which offers the world's most extensive biological variety. This study utilizes a multi-model ensemble (MME) of 16 CMIP6 Global Climate Models (GCMs) to assess prospective alterations in thermal bioclimatic indicators (TBIs) across the coastal region of the Ganges Delta (GD) for two Shared Socioeconomic Pathways (SSPs): SSP245 (moderate) and SSP585 (severe). We employ ensemble median, 5th, and 95th percentiles to analyze temporal shifts and associated uncertainty in TBIs during the near (2020–2059) and far (2060–2100) futures. Our projections reveal a significant escalation in annual temperatures throughout the GD, with MME median average in-crease anticipated to range from 0.77–2.80°C (SSP2-4.5) to 1.03–4.65°C (SSP5-8.5) by 2059. Moreover, notable transformations in thermal patterns are expected, with a projected decrease in both diurnal temperature range (DTR) by 0.02–0.87°C and isothermality by 3.30-12.09%. Additionally, the average temperature during the driest months is anticipated to rise higher than in the wettest months. These findings underscore climate change's existential threat to the GD and its rich biodiversity. They provide vital information for formulating crucial mitigation strategies to curb greenhouse gas emissions and robust adaptation measures to bolster the resilience of communities and eco-systems. Urgent action is paramount to safeguard the future of this invaluable ecological treasure.