<p>Green hydrogen has emerged as a strategic option for deep decarbonisation in industry, transport, and power balancing, yet most studies treat cost, climate, water, health, and equity as separate questions rather than one coupled decision space. This study addresses that gap through an integrated scenario framework that combines power system dispatch, hydrogen production and logistics, life cycle climate accounting, air pollutant exposure, health impact functions, and distributional assessment across North America, Europe, Middle East and North Africa, Sub-Saharan Africa, Latin America, and Asia Pacific under six policy and constraint pathways. The main contribution lies in quantifying tradeoffs across technical environmental social and governance dimensions within one harmonised structure. Results show regional hydrogen costs from $1.70 to $3.40 kg^⁻1, with electricity contributing 44 to 60% of total cost and utilisation ranging from 45 to 68%. Life cycle climate intensity declines from 170 to 80 g carbon dioxide equivalent MJ^⁻1 hydrogen, while criteria pollutant reductions reach 250 kt year^⁻1. Basin-level water availability limits of 35,000 to 90,000 m³ day^⁻1 reduce hydrogen production by 15 to 30%, highlighting the need for non-potable water sourcing and other mitigation measures.</p>