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Most urban residents in high-income countries obtain piped and treated water for drinking and domestic use from centralized utility-run water systems. In low- and middle-income countries (LMICs), however, utilities work alongside myriad other service providers that deliver water to hundreds of millions of city-dwellers. Hybrid modes of water delivery in urban areas in low- and middle-income countries are systems in which a variety of state and nonstate actors contribute to the delivery of water to households, schools, healthcare facilities, businesses, and government offices. Historically, the field has evolved to include within-utility networks and outside-the-utility provision mechanisms. Utilities service the urban core through network connections, while nonstate, smaller-scale providers supplement utility services both inside and outside the piped network. The main reform waves since the 1990s—privatization and corporatization—have done little to alter the hybrid nature of provision. Numerous case studies of nonutility water providers suggest that they are imperfect substitutes for utilities. They reach millions of households with no access to piped water, but the water they deliver tends to be of uncertain quality and is typically far more expensive than utility water. Newer work on utility-provided water and utility reforms has highlighted the political challenges of private sector participation in urban water; debates have also focused on the importance of contractual details such as tariff structures and investor incentives. New research has produced numerous studies on LMICs on the ways in which utilities extend their service areas and service types through explicit and implicit relationships with front-line water workers and with supplemental nonstate water suppliers. From the nonutility perspective, debates animated by questions of price and quality, the desirability or possibility of regulation, and the compatibility (or lack thereof) between reliance on small-scale water providers and the human right to safe water, are key areas of research. While understanding the hybrid nature of water delivery is essential for responsible policy formulation and for understanding inequalities in the urban sphere, there is no substitute for the convenience and affordability of universal utility provision, and no question that research on the conditions under which particular types of reforms can improve utility provision is sorely needed. 

During the 1930s Dust Bowl drought in the central United States, species with the C₃photosynthetic pathway expanded throughout C₄-dominated grasslands. This widespread increase in C₃grasses during a decade of low rainfall and high temperatures is inconsistent with well-known traits of C₃vs. C₄pathways. Indeed, water use efficiency is generally lower, and photosynthesis is more sensitive to high temperatures in C₃than C₄species, consistent with the predominant distribution of C₃grasslands in cooler environments and at higher latitudes globally. We experimentally imposed extreme drought for 4 y in mixed C₃/C₄grasslands in Kansas and Wyoming and, similar to Dust Bowl observations, also documented three- to fivefold increases in C₃/C₄biomass ratios. To explain these paradoxical responses, we first analyzed long-term climate records to show that under nominal conditions in the central United States, C₄grasses dominate where precipitation and air temperature are strongly related (warmest months are wettest months). In contrast, C₃grasses flourish where precipitation inputs are less strongly coupled to warm temperatures. We then show that during extreme drought years, precipitation–temperature relationships weaken, and the proportion of precipitation falling during cooler months increases. This shift in precipitation seasonality provides a mechanism for C₃grasses to respond positively to multiyear drought, resolving the Dust Bowl paradox. Grasslands are globally important biomes and increasingly vulnerable to direct effects of climate extremes. Our findings highlight how extreme drought can indirectly alter precipitation seasonality and shift ecosystem phenology, affecting function in ways not predictable from key traits of C₃and C₄species.