Climate change and variability impacts on the forests of Bangladesh – a diagnostic discussion based on CMIP5 GCMs and ENSO

Abstract

ABSTRACTThe aim of this study is to assess the evolution of forests in Bangladesh from the perspective of changing climate, with particular emphasis on the Sundarbans, the world's largest mangrove forest. Projections for temperature and rainfall change have been made using the latest Intergovernmental Panel on Climate Change‐Fifth Assessment Report (IPCC‐AR5) general circulation models (GCMs) protocol (Coupled Model Intercomparison Project Phase 5, CMIP5) with 38 various GCMs and up to 105 model runs. The GCMs findings were verified by the published results of 11 regional climate models (RCMs) in the Coordinated Regional Climate Downscaling Experiment (CORDEX)‐South Asia models with finer spatial resolution. A CMIP5 model‐based synthesis review on the future variability of El Niño‐Southern Oscillation (ENSO) has also been made, as both the seasonal temperature and rainfall variability in Bangladesh are correlated to ENSO. Both global and regional climate change scenarios indicate that temperature would continue to rise and total annual rainfall is likely to increase in the future. However, weak increases in rainfall combined with high increases in temperature would create a high demand and competition for water because of the higher evapotranspiration environment. In addition to changing climate, the interannual variability of ENSO would further aggravate problems because it displays important correlations with the variability of rainfall, temperatures, sea‐level, lightning, and forest fires in Bangladesh. This study strongly recommends that future climate change projections should be combined with interannual variability ENSO to improve climate perspectives for stronger forest capacity building efforts in Bangladesh.