The study provides the first experimental demonstration of the potential impacts of climate change on water movement through grassland ecosystems, which make up nearly 40% of Earth's land area and play a critical role in Earth's water cycle. The study appears in the journal Science.

"If we want to predict the effects of climate change on Earth's water resources, we need data showing how the hydrologic cycle will respond at a small scale where we can define mechanisms, but that just hasn't been available," said Jesse Radolinski, corresponding author of the study, a post-doctoral research associate in the UMD Department of Environmental Science & Technology who began the work at the University of Innsbruck.

"Our experiments found that under summer drought conditions, and higher air temperatures that are expected under a future with elevated CO₂, two things change fundamentally: One, the structural properties of the soil in the root zone change so that water flows differently than we expected, and two, these altered climate conditions and soil properties cause the plants to access water differently."

Currently, new rainfall tends to linger in the root zone where it mixes with existing soil water (i.e., previous rainfall) before percolating into local streams and rivers.