Linking IPCC AR4 & AR5 frameworks for assessing vulnerability and risk to climate change in the Indian Bengal Delta

The term ‘vulnerability’ is used to examine the interlinkages between humans and their social and physical surroundings. This approach is similar to the IPCC AR4's (2007) conceptual framework of vulnerability to climate change. The IPCC AR5 (2014) introduces a new approach and terminology that is in line with the concept of risk, thus differing from the previous understanding of vulnerability as mentioned in the IPCC AR4. This study attempts to link the new concept of risk (AR5) with the previous concept of vulnerability (AR4). Based on IPCC AR4 and AR5 frameworks, different bio-physical and socio-economic variables have been used for vulnerability (AR4) and risk (AR5) assessments in the 51 sub-districts (community development blocks) of the Indian part of Ganges-Brahmaputra-Meghna Delta (Indian Bengal Delta or IBD) applying principal component analysis (PCA). The results show that Basanti is the most vulnerable sub-district using the AR4 approach, whereas Gosaba is found to be the highly exposed to risk using the AR5 approach. Both sub-districts are spatially contiguous and with similar geographic characteristics which reflects the validity of the IPCC frameworks of assessment.