Riverine flood plains are among the most biologically productive and diverse ecosystems on Earth, covering over 2 million km² globally. However, they are among the most threatened ecosystems, with up to 90% already 'cultivated' and functionally extinct in Europe and North America. In the developing world, natural flood plains are disappearing rapidly due to changing hydrology. By 2025, human population growth will further degrade riparian areas, intensify the hydrological cycle, increase pollutant discharge, and promote species invasions. The most threatened flood plains will be in Southeast Asia, Sahelian Africa, and North America. There is an urgent need to preserve intact floodplain rivers as strategic global resources and restore hydrologic dynamics, sediment transport, and riparian vegetation. Flood plains are centers of biodiversity and bioproduction, supporting a wide range of species and providing essential ecosystem services such as disturbance regulation, water supply, and waste treatment. They are highly productive, with net primary production in riparian forests ranging from 750 to 1370 g m² yr⁻¹. Flood plains contribute over 25% of all terrestrial ecosystem services, despite covering only 1.4% of the land surface. Their economic value is estimated at US$ 3920 × 10⁹ yr⁻¹, with significant contributions from nitrogen removal, recreation, and other services. Human activities, including habitat alteration, pollution, and invasive species, are major threats to flood plains. Habitat alteration, such as dam construction and land conversion, has drastically reduced floodplain areas, with some regions losing up to 50% of their historic expanse. Pollution from agricultural and industrial activities has led to severe water quality issues, with many rivers too polluted to support fisheries. Species invasions, driven by land transformation and altered hydrology, have led to the dominance of non-native species in many river systems. Climate change and increasing human population will further threaten flood plains, leading to changes in water cycles, increased flooding, and reduced water availability. By 2025, water demand for irrigation is expected to increase significantly, with many developing countries facing severe water shortages. The construction of dams and irrigation projects will continue to alter river systems, reducing sediment transport and changing the chemistry of river inputs. Flood plains are particularly sensitive to changes in river hydrology, land-water interface alterations, and nutrient inputs. The loss of flood plains will have severe consequences for biodiversity, ecosystem services, and human communities. Conservation and restoration efforts are essential to preserve these vital ecosystems and ensure their continued contribution to global biodiversity and ecological services.Riverine flood plains are among the most biologically productive and diverse ecosystems on Earth, covering over 2 million km² globally. However, they are among the most threatened ecosystems, with up to 90% already 'cultivated' and functionally extinct in Europe and North America. In the developing world, natural flood plains are disappearing rapidly due to changing hydrology. By 2025, human population growth will further degrade riparian areas, intensify the hydrological cycle, increase pollutant discharge, and promote species invasions. The most threatened flood plains will be in Southeast Asia, Sahelian Africa, and North America. There is an urgent need to preserve intact floodplain rivers as strategic global resources and restore hydrologic dynamics, sediment transport, and riparian vegetation. Flood plains are centers of biodiversity and bioproduction, supporting a wide range of species and providing essential ecosystem services such as disturbance regulation, water supply, and waste treatment. They are highly productive, with net primary production in riparian forests ranging from 750 to 1370 g m² yr⁻¹. Flood plains contribute over 25% of all terrestrial ecosystem services, despite covering only 1.4% of the land surface. Their economic value is estimated at US$ 3920 × 10⁹ yr⁻¹, with significant contributions from nitrogen removal, recreation, and other services. Human activities, including habitat alteration, pollution, and invasive species, are major threats to flood plains. Habitat alteration, such as dam construction and land conversion, has drastically reduced floodplain areas, with some regions losing up to 50% of their historic expanse. Pollution from agricultural and industrial activities has led to severe water quality issues, with many rivers too polluted to support fisheries. Species invasions, driven by land transformation and altered hydrology, have led to the dominance of non-native species in many river systems. Climate change and increasing human population will further threaten flood plains, leading to changes in water cycles, increased flooding, and reduced water availability. By 2025, water demand for irrigation is expected to increase significantly, with many developing countries facing severe water shortages. The construction of dams and irrigation projects will continue to alter river systems, reducing sediment transport and changing the chemistry of river inputs. Flood plains are particularly sensitive to changes in river hydrology, land-water interface alterations, and nutrient inputs. The loss of flood plains will have severe consequences for biodiversity, ecosystem services, and human communities. Conservation and restoration efforts are essential to preserve these vital ecosystems and ensure their continued contribution to global biodiversity and ecological services.