The world is getting wetter, yet water may become less available for North America and Eurasia
Nov 6, 2019 at 5:00pm
With climate change, plants of the future will consume more water than in the present day, leading to less water available for people living in North America and Eurasia, according to a Dartmouth-led study in Nature Geoscience. The research suggests a drier future despite anticipated precipitation increases for places like the United States and Europe, populous regions already facing water stresses.
The study challenges an expectation in climate science that plants will make the world wetter in the future. Scientists have long thought that as carbon dioxide concentrations increase in the atmosphere, plants will reduce their water consumption, leaving more freshwater available in our soils and streams. This is because as more carbon dioxide accumulates in our atmosphere plants can photosynthesize the same amount while partly closing the pores (stomata) on their leaves. Closed stomata means less plant water loss to the atmosphere, increasing water in the land. The new findings reveal that this story of plants making the land wetter is limited to the tropics and the extremely high latitudes, where freshwater availability is already high and competing demands on it are low. For much of the mid-latitudes, the study finds, projected plant responses to climate change will not make the land wetter but drier, which has massive implications for millions of people.
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