Water scarcity is dynamic and complex, emerging from the combined influences of climate change, basin-level water resources, and managed systems’ adaptive capacities. Beyond geophysical stressors and responses, it is critical to also consider how multi-sector, multi-scale economic teleconnections mitigate or exacerbate water shortages. Here, we contribute a global-to-basin-scale exploratory analysis of potential water scarcity impacts by linking a global human-Earth system model, a global hydrologic model, and a metric for the loss of economic surplus due to resource shortages. We find that, dependent on scenario assumptions, major hydrologic basins can experience strongly positive or strongly negative economic impacts due to global trade dynamics and market adaptations to regional scarcity. In many cases, market adaptation profoundly magnifies economic uncertainty relative to hydrologic uncertainty. Our analysis finds that impactful scenarios are often combinations of standard scenarios, showcasing that planners cannot presume drivers of uncertainty in complex adaptive systems.

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Productive land is a scarce resource with a decreasing supply (Gomiero, 2016) but ever growing demands (Gomiero, 2016;Lambin & Meyfroidt, 2011). Increasing population and wealth cause greater demand for crops, meat, and other agricultural products and therefore for the water and energy resources needed to produce these products. At the same time, non-commercial land is an integral part of most environmental objectives. Land conservation is necessary to maintain biodiversity and healthy stable ecosystems (Thompson et al., 2009), and forests and soils are valuable carbon sinks that aid in mitigating severe climate change (Asner et al., 2004;Lal, 2004). These services improve the long-term quality of life on Earth and help achieve the relatively near-term goals of international environmental agreements such as the Convention on Biodiversity and the Paris Accords. The competing multi-sector demands for land (Carrasco et al., 2017;Dooley et al., 2018;Grass et al., 2020;Meyfroidt, 2018) emphasize the importance of modeling land scarcity in the context of the complex coupled human-Earth system. To more fully understand the multisector dynamics that drive land scarcity and its impacts, multiple metrics should be evaluated so that synergies and tradeoffs between competing sectors are made known (Kroll et al., 2019;van Vuuren et al., 2015). Further, these dynamics should be analyzed in the context of the abundant uncertainty present in the system. Dynamics may shift depending on the circumstances and it is important to understand the drivers of these dynamical shifts so that planners can make decisions that are robust to future changes. Other land use studies assess multiple impact metrics without explicitly accounting for future uncertainty (Kroll et al., 2019;van Vuuren et al., 2015) or assess economic (Waldron et al., 2020) or environmental (Borrelli et al., 2020;Mouratiadou et al., 2016) impacts under uncertainty, but few studies implement all of these elements (Gao & Bryan, 2017). Considering only one metric may lead to myopic decisions and high regret, whereas failing to account for uncertainty can lead to decisions that leave the population vulnerable to high losses (Reckhow, 1994).

Future water scarcity is a global concern with impacts across the energy, water, and land (EWL) sectors. Countries in Latin America and the Caribbean (LAC) are significant producers of agricultural goods, so disruptions resulting from water scarcity in LAC have global importance. Understanding where water scarcity in LAC could occur and what could exacerbate it is critical for strategic resource management and planning, both regionally and globally. Assessing future water scarcity in LAC is challenging given the complex interactions among the EWL sectors and the multiple uncertainties acting across spatial scales. To illuminate these dynamics, we use scenario discovery on a large ensemble representing diverse futures simulated using an integrated human‐environmental systems model. We quantify future water scarcity and its economic impacts across several physical and economic metrics. We find that future levels of reservoir storage expansion could be a significant driver of physical and economic water scarcity, highlighting the importance of strategic water infrastructure development in maintaining future water availability. Changes in crop profit are driven by both water supply and demand, emphasizing the complexity of EWL multisector dynamics. While most of LAC is poised to have abundant land and water resources available for future development, basins in Mexico and along the Pacific coast of South America experience high exposure to severe outcomes and uncertainty across outcomes for at least one metric. We find that drivers of severe scarcity vary spatially and across metrics, highlighting the region's heterogeneity and the importance of considering multiple metrics to assess water scarcity.

Productive land is a scarce resource with a decreasing supply (Gomiero, 2016) but ever growing demands (Gomiero, 2016;Lambin & Meyfroidt, 2011). Increasing population and wealth cause greater demand for crops, meat, and other agricultural products and therefore for the water and energy resources needed to produce these products. At the same time, non-commercial land is an integral part of most environmental objectives. Land conservation is necessary to maintain biodiversity and healthy stable ecosystems (Thompson et al., 2009), and forests and soils are valuable carbon sinks that aid in mitigating severe climate change (Asner et al., 2004;Lal, 2004). These services improve the long-term quality of life on Earth and help achieve the relatively near-term goals of international environmental agreements such as the Convention on Biodiversity and the Paris Accords. The competing multi-sector demands for land (Carrasco et al., 2017;Dooley et al., 2018;Grass et al., 2020;Meyfroidt, 2018) emphasize the importance of modeling land scarcity in the context of the complex coupled human-Earth system. To more fully understand the multisector dynamics that drive land scarcity and its impacts, multiple metrics should be evaluated so that synergies and tradeoffs between competing sectors are made known (Kroll et al., 2019;van Vuuren et al., 2015). Further, these dynamics should be analyzed in the context of the abundant uncertainty present in the system. Dynamics may shift depending on the circumstances and it is important to understand the drivers of these dynamical shifts so that planners can make decisions that are robust to future changes. Other land use studies assess multiple impact metrics without explicitly accounting for future uncertainty (Kroll et al., 2019;van Vuuren et al., 2015) or assess economic (Waldron et al., 2020) or environmental (Borrelli et al., 2020;Mouratiadou et al., 2016) impacts under uncertainty, but few studies implement all of these elements (Gao & Bryan, 2017). Considering only one metric may lead to myopic decisions and high regret, whereas failing to account for uncertainty can lead to decisions that leave the population vulnerable to high losses (Reckhow, 1994).