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Wetlands have long been drained for human use, thereby strongly affecting greenhouse gas fluxes, flood control, nutrient cycling and biodiversity1,2. Nevertheless, the global extent of natural wetland loss remains remarkably uncertain3. Here, we reconstruct the spatial distribution and timing of wetland loss through conversion to seven human land uses between 1700 and 2020, by combining national and subnational records of drainage and conversion with land-use maps and simulated wetland extents. We estimate that 3.4 million km2(confidence interval 2.9–3.8) of inland wetlands have been lost since 1700, primarily for conversion to croplands. This net loss of 21% (confidence interval 16–23%) of global wetland area is lower than that suggested previously by extrapolations of data disproportionately from high-loss regions. Wetland loss has been concentrated in Europe, the United States and China, and rapidly expanded during the mid-twentieth century. Our reconstruction elucidates the timing and land-use drivers of global wetland losses, providing an improved historical baseline to guide assessment of wetland loss impact on Earth system processes, conservation planning to protect remaining wetlands and prioritization of sites for wetland restoration4.

Covering 10% of the world’s hydropower reservoirs with ‘floatovoltaics’ would install as much electrical capacity as is currently available for fossil-fuel power plants. But the environmental and social impacts must be assessed.

Intensive fisheries have reduced fish biodiversity and abundance in aquatic ecosystems worldwide1–3. ‘No-take’ marine reserves have become a cornerstone of marine ecosystem-based fisheries management4–6, and their benefits for adjacent fisheries are maximized when reserve design fosters synergies among nearby reserves7,8. The applicability of this marine reserve network paradigm to riverine biodiversity and inland fisheries remains largely untested. Here we show that reserves created by 23 separate communities in Thailand’s Salween basin have markedly increased fish richness, density, and biomass relative to adjacent areas. Moreover, key correlates of the success of protected areas in marine ecosystems—particularly reserve size and enforcement—predict differences in ecological benefits among riverine reserves. Occupying a central position in the network confers additional gains, underscoring the importance of connectivity within dendritic river systems. The emergence of network-based benefits is remarkable given that these reserves are young (less than 25 years old) and arose without formal coordination. Freshwater ecosystems are under-represented among the world’s protected areas9, and our findings suggest that networks of small, community-based reserves offer a generalizable model for protecting biodiversity and augmenting fisheries as the world’s rivers face unprecedented pressures10,11.