Drawing on a host of scientific studies, this text explores how rising levels of CO2 in the atmosphere have impacted water in plants and soils. It discusses drought, the soil-plant-atmosphere continuum, the soil atmosphere, root growth, and variable oxygen concentration of soil. The book also covers the use of carbon isotope ratios in plant science, stomatal conductance and density, transpiration and evapotranspiration, water use efficiency, C4 photosynthesis, plant anatomy, phenology, and measures of plant growth. More than 200 high quality figures illustrate the concepts discussed.