Prospective water scarcity footprint under climate change applied to bio-based sustainable aviation fuel production...

The transition of aviation from fossil to sustainable aviation fuels (SAFs) raises concerns about its water requirements in an increasingly water-stressed world, highlighting the need for integrated water footprint assessments under climate change. This study first develops novel water scarcity footprint factors projected monthly and annually until 2099 at a 0.5° × 0.5° global resolution under eight climate change scenarios. Significant regional and temporal disparities are revealed, with future factors differing by more than 50% from historical values in many regions. Applying these dynamic factors to projected global SAF production shows that Asia contributes to more than 50% of the global future water scarcity footprint, while North America exhibits lower impacts despite high production volumes. By demonstrating that historical factors underestimate future impacts, particularly under high-emission scenarios, these findings emphasize the importance of prospective environmental assessments to ensure that energy transition does not endanger water security.