Arabic coffee plants grown under elevated CO2 levels showed increased photosynthesis and reduced water loss compared to plants grown under normal CO2 levels. The study aimed to measure photosynthesis, stomatal conductance, and transpiration in coffee plants after five years of cultivation under different CO2 conditions. The researchers found that plants under elevated CO2 had higher photosynthetic rates, especially in dry seasons, and used water more efficiently. The highest and lowest plant layers benefited the most from elevated CO2, while shaded leaves showed different responses. Overall, the results suggest that coffee plants can better conserve water under elevated CO2 levels, especially in high light conditions.