Leaf hydraulic properties are strongly linked with transpiration and photosynthesis in many species, but it is not known if gas exchange and hydraulics will have co-ordinated responses to climate change. Locke et al.study soybean (Glycine max) and find that leaf hydraulic conductance (K_leaf) does not change for plants grown at elevated [CO₂] or elevated temperature, despite changes in photosynthesis and stomatal conductance. This lack of coordination between K_leaf and gas exchange in response to growth environment is observed in both field- and chamber-grown soybeans. Such an imbalance could lead to hydraulic limitation of photosynthesis under extreme environmental conditions.