Climate impact on blue economy index: Bayesian spatio-temporal regression with statistical downscaling in Sumatera

Climate change studies inherently involve spatial, temporal, and regional dimensions, while the blue economy’s sustainability is significantly influenced by global climate factors. Sumatera, a key conservation region in Indonesia, faces challenges in managing its marine resources. Limited quantitative research at regency/city level led to the development of Blue Economy Index (BEI) as a measurement tool. This study constructs a BEI from 38 environmental, economic, and social indicators also identifies global climate variables affecting BEI significantly among five analyzed using best spatio-temporal statistical downscaling model with INLA approach. From 2019 to 2022, Medan City consistently achieved the highest BEI scores, while Subulussalam City recorded the lowest. The optimal model through WAIC, a nonparametric model with unstructured space-time interaction, revealed that skin temperature, sea level pressure, and precipitation significantly affect BEI. Unstructured spatial variation mainly influences BEI, while temporal trends show a decline in 2021 due to Covid-19, with dynamic spatial-temporal effects.