Climate warming is tightening its grip on terrestrial water supplies, intensifying drought risks worldwide. For years, scientists have pointed to a silver lining: rising atmospheric CO₂ causes plants to partially close their leaf pores, or stomata, reducing water loss while still taking in carbon. This so-called water-use efficiency was thought to help buffer against drying landscapes.
But a recent study published on Phys.org suggests this perceived benefit may be severely overestimated. Researchers argue that earlier models and assumptions painted an overly optimistic picture of how vegetation responds to elevated CO₂ levels. The finding upends a key assumption embedded in many climate projections.
The study's authors caution that relying on this 'water-saving' effect could lead to underestimating future drought severity. They call for more realistic representations of plant physiology in Earth system models, warning that current predictions may be too rosy.
If confirmed, the research implies that water scarcity in a warming world could hit harder and sooner than anticipated. This would have profound implications for agriculture, water resource management, and ecosystems already under stress from rising temperatures.
The counter_argument remains that some field experiments have shown measurable improvements in plant water-use efficiency under elevated CO₂. However, the study suggests these gains may be context-dependent and not scalable across global biomes.