Balance of nature: the water cycle (Introduction)

by David Turell , Saturday, January 11, 2025, 21:02 (11 days ago) @ David Turell

Fast and slow rates of conversion:

https://www.sciencedaily.com/releases/2025/01/250109183329.htm

"A new study led by scientists in the Schmid College of Science and Technology at Chapman University provides the first comprehensive global estimates of the amount of water stored in Earth's plants and the amount of time it takes for that water to flow through them. The information is a missing piece of the puzzle in understanding the global water cycle and how that cycle is being altered by changes in land use and climate.

"The study, published today, January 9, in the journal Nature Water, finds that Earth's vegetation stores about 786 km3 of water, only about 0.002% of the total amount of freshwater stored on Earth. The study also finds that the time it takes for water to flow through plants (referred to as transit or turnover time) and return to the atmosphere is among the fastest in the global water cycle, ranging from just five days in croplands to 18 days in evergreen needleleaf forests. The transit of water through plants is particularly fast in croplands, grasslands and savannas. The results underscore vegetation's dynamic role in the water cycle. In comparison to the global annual median of 8.1 days for water to transit through plants from entry to exit, the water in lakes is estimated to take 17 years, and the water in glaciers is estimated to take 1600 years.

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"The team combined estimates of plant water storage with cutting-edge estimates of the rates at which water is leaving plants to determine the transit time of water through vegetation. The result was five years of monthly water storage and transit time estimates at a spatial resolution of 9 km2.

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"'One important observation is that croplands around the world tend to have very similar and very fast transit times," said Dr. Gregory Goldsmith, senior author and an associate professor of Biological Sciences 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 results suggest that the transit time of water through plants is likely to be very sensitive to events such as deforestation, drought and wildfire, which will fundamentally change the time it takes for water to flow through the water cycle," Felton said."

Comment: How we treat the land and its plants has an direct effect on the water cycle. It is important for us to understand those effects and be sure they are not detrimental.