Human factors are projected to be the dominant driver of future water scarcity on a global scale . However, at regional scales, high uncertainty in climate changes means that reduced water availability is more likely than not in many major river basins and remains a risk in most basins even where the central estimate is for increased water availability due to climate change . Such substantial uncertainties in projected water scarcity are crucial factors causing water management policies and planning challenges in the future. Therefore, locations projected to see significant increases in water scarcity with large uncertainty can be considered to be subject to the highest challenges for water management policy .
IPCC
Climate Change 2022: Impacts, Adaptation and Vulnerability
IPCC Report