Approach
In this two-fold project, we are first working on systematically mapping temporal trends in total water availability (often called “total water storage”) worldwide, uncovering regions facing both extreme water loss and gain. By overlaying trends in various water resources with additional data such as population density, poverty levels, and agricultural productivity, we are identifying populations and agricultural output most vulnerable to changes in water storage. Using statistical analyses linking high-resolution water storage data to climatological and agricultural conditions, we identify the impact of warming, wetting/drying, and irrigation activity on water storage trends at global scale. This empirical decomposition enables us to discern whether shifts in total water storage are a result of agricultural water usage, climatic factors like changes in rainfall and temperature, or a combination of both. We use these analyses to conduct a set of future simulations that uncover water stress hotspots that are likely to emerge under future climatological and/or agricultural conditions.
In the second component of our project, we are evaluating the global economic significance of moisture transport. Increasingly, hydrologists are uncovering the spatial linkages (often called “teleconnections”) that tie evapotranspiration in one region of the world to precipitation in another. The spatial structure and strength of these links have potentially important implications for land management and future forecasting, as rainfall patterns are likely to be determined not just by large-scale climatic factors, but also by land use patterns in teleconnected regions. In this second phase of our project, we use new modeling output to map and identify the global regions that are crucial for generating land-based recycling; that is, the regions generating moisture that later falls as rainfall on other land parcels. These regions represent priorities for conservation of evapotranspiration, for example through preserving native forests. We then intersect this analysis with spatial data on social and economic outcomes, identifying the populations and agricultural regions that are most dependent on precipitation generated by land-based recycling. In a simulation analysis, we estimate the total economic value of atmospheric moisture flows, and compute the economic implications of precipitation changes resulting from local and non-local changes in land use.
Together, these analyses provide the first comprehensive global picture of the causes and consequences of water imbalances. They will be used to inform a multi-faceted report developed by the Global Commission on the Economics of Water, set to be released in late 2024.
