Scientists have discovered that water moves through plants and returns to the atmosphere far more quickly than previously thought – taking just days rather than the months or years it takes to cycle through other parts of Earth’s water system. The finding reshapes our understanding of the global water cycle and could have significant implications for climate predictions and ecosystem management.
Speed of Nature
“Plants are the forgotten part of the global water cycle,” explains Dr. Andrew Felton, who led the research while at Chapman University. “In many cases, plants are not even represented on water cycle diagrams, which is ironic because we already know they play this critical role in returning water from the ground to the atmosphere.”
The study, published in Nature Water, found that water moves through vegetation in just 5 to 18 days, with croplands showing the fastest transit times and evergreen forests the slowest. This is remarkably quick compared to other parts of the water cycle – it takes about 17 years for water to cycle through lakes and 1,600 years through glaciers.
Using data from NASA’s soil moisture satellite mission, the researchers discovered that Earth’s vegetation stores about 786 cubic kilometers of water – a surprisingly small amount representing just 0.002% of Earth’s total freshwater. Yet despite this small volume, plants play an outsized role in the water cycle.
Climate Change Implications
“One important observation is that croplands around the world tend to have very similar and very fast transit times,” notes Dr. Gregory Goldsmith, senior author and associate professor at Chapman University. “This indicates that land use change may be homogenizing the global water cycle and contributing to its intensification by more rapidly recycling water back to the atmosphere where it can turn into heavy rain events.”
The research team found that different types of vegetation handled water transit quite differently. Croplands processed water in less than a day during peak growing season, while forests took longer due to their larger biomass. These findings suggest that changes in land use, such as deforestation or agricultural expansion, could fundamentally alter how water moves through the ecosystem.
The study combined novel analysis of satellite data with ground measurements to create the first comprehensive global map of how water moves through vegetation. The research represents five years of monthly measurements across the globe at a detailed resolution of 9 square kilometers.
The findings could have particular significance for understanding and predicting extreme weather events, as the speed at which water returns to the atmosphere influences precipitation patterns and storm formation.
The research was published in Nature Water.