Using land surface model experiments to improve understanding of alteration of the global water cycle from human land cover and climate change

This research program will address pressing scientific questions in global change and water availability by using a combination of land surface modelling experiments and new climate, evapotranspiration, and land cover datasets. Emphasis will be placed on quantitative interpretation of how land cover and climate change interact to alter evapotranspiration and runoff on the continents. Freshwater availability on our planet is determined by continental rates of water cycling and storage. Human activity alters the continental water cycle through three key ways: direct water withdrawals, climate change, and land cover change. Recent advances show that these three dominating agents alter continental runoff by similar magnitudes; in particular, climate change and land cover change alter annual average runoff by similar magnitude, but in opposite directions. This new knowledge raises a critical scientific problem: over the next century, how will climate change and land cover change interact to alter water availability across the planet? Where will the effects of land cover and climate change be magnified, and where will their effects cancel out? Over the next five years, this research program will focus on two direct objectives: 1) create new datasets for land cover and climate for two future scenarios, and 2) conduct numerical experiments with a global land surface model, controlling to test relative and combined impacts of land cover and climate change in current and future scenarios. Achieving these objectives will reduce uncertainty in critical water issues and improve our ability to respond to climate change.