>Climate models are essential for providing insight into the planet's complex weather systems and predicting how they might change in the future.
>However, researchers have identified a major gap in the way some of these models represent how plants respond to drought, which could have significant implications for understanding global water cycles and future precipitation patterns.
How plants respond to dehydration. The research, published in the journal Nature Geoscience, focuses on how plants regulate the loss of water through small pores on their leaves called stomata. When water is plentiful, plants open their stomata to take in carbon dioxide for photosynthesis. But when faced with drought, plants close their stomata to conserve water.
Closing stomata has an impact on water cycles. This stomatal regulation also affects the amount of water vapor released into the atmosphere through a process known as transpiration. It's estimated that plants contribute about 90 percent of the Earth's water vapor, so when they begin closing their stomata during a drought, it impacts the water available in the atmosphere for cloud formation and precipitation.
What the models miss. The researchers compared several global climate models to satellite observations of plant behavior during real-world droughts. They found that the models underestimated the degree to which plants close their stomata during droughts. This led the models to overestimate the amount of plant-derived water vapor in the atmosphere and, in turn, predict more rainfall than what actually occurred.
Implications for climate change. The findings suggest that climate models could produce overly optimistic projections of future rainfall patterns, especially during drought events. This has important implications for water management and the resilience of ecosystems around the world.
"If we don't have a more accurate representation of how plants respond to drought in our models, we may not properly predict how the water cycle will change under future climate projections that are likely to involve more frequent and severe droughts," said study co-author Benjamin Quesada.
The research team says that addressing this gap in climate models will require further experiments and observations that directly link plant water use to rainfall patterns.
