Using a Water Scarcity Index  defined as the ratio of demand and availability, accounting for EFRs, it is estimated that 4 billion people live under conditions of severe water scarcity for at least one month per year . Nearly half of these people live in India and China. Although regions with high water scarcity are already naturally dry , human influence on climate is leading to reduced water availability in many regions. It is very likely that global patterns of soil moisture change are being driven by human influence on climate, and an overall global decline in soil moisture is attributable to greenhouse forcing . Climate change patterns of streamflow change include declines in western North America, northeast South America, the Mediterranean and South Asia  . However, quantification of the contribution of anthropogenic climate change to current levels of water scarcity is not yet available.
IPCC
Climate Change 2022: Impacts, Adaptation and Vulnerability
IPCC Report