A new look at Earth’s water and energy with SWOT

As the planet transitions to a new climate, adapting to the Earth’s changing water cycle remains among the top challenges faced by humanity. The relative stability of climate and water resources over the past millennia allowed humans to build complex societies with established agriculture, infrastructure and economies that today sustain the livelihood of eight billion people. As the planet warms, this steady state of water movement is being altered, and both oceanic and terrestrial components of the global water cycle are undergoing measurable changes that will probably continue. Predicting the new trajectory of Earth’s water in a warming climate begins with observing the entire water supply–demand chain across the planet, from Earth’s largest water reservoir, the ocean, to water storage, use and recycling on land. A recently launched space observatory, called the Surface Water and Ocean Topography (SWOT), is making a timely entrance and addition to the water-observing networks, by providing direct, high-resolution measurements of the water height and volume of nearly all water on the Earth’s surface. Here we link technological advances in wide-swath satellite altimetry and SWOT’s novel measurements of water volume across the planet to scientific innovations for Earth’s water cycle, including studies of changes in the water storage and dynamics in global lakes and rivers, rising seas, ocean energetics and land–ocean exchange, with implications for practical information for water resource managers and climate resilience efforts. We also discuss how SWOT innovations set the stage for future missions and integrated Earth-system approaches within the water science community. The new SWOT satellite mission tracks global water supply–demand and land-to-ocean water movement, leading the way towards an integrated satellite observatory that can help humanity adapt to Earth’s shifting water and energy systems.