The future of evapotranspiration: global requirements for ecosystem functioning, carbon and climate feedbacks, agricultural management, and water resources

Authors: FISHER, JOSHUA - CALIFORNIA INSTITUTE OF TECHNOLOGY; MIDDLETON, ELIZABETH - NASA GODDARD INSTITUTE FOR SPACE STUDIES; MELTON, FORREST - NATIONAL AERONAUTICS AND SPACE ADMINISTRATION (NASA); Anderson, Martha; HOOK, SIMON - CALIFORNIA INSTITUTE OF TECHNOLOGY; HAIN, CHRISTOPHER - NATIONAL OCEANIC & ATMOSPHERIC ADMINISTRATION (NOAA); ALLEN, RICHARD - UNIVERSITY OF IDAHO; MCCABE, MATTHEW - KING ABDULLAH UNIVERSITY OF SCIENCE AND TECHNOLOGY; LAGOUARDE, JEAN-PIERRE - INLAND NORTHWEST RESEARCH ALLIANCE, INRA; TU, KEVIN - DUPONT PIONEER HI-BRED; BALDOCCHI, DENNIS - UNIVERSITY OF CALIFORNIA; TOWNSEND, PHILIP - UNIVERSITY OF WISCONSIN; KILIC, AYSE - UNIVERSITY OF NEBRASKA; PERRET, JOHAN - EARTH UNIVERSITY; MIRALLES, DIEGO - VU UNIVERSITY MEDICAL CENTER; WALISER, DUANE - CALIFORNIA INSTITUTE OF TECHNOLOGY; FRENCH, ANDREW; SCHIMEL, DAVID - CALIFORNIA INSTITUTE OF TECHNOLOGY; FAMIGLIETTI, JAY - CALIFORNIA INSTITUTE OF TECHNOLOGY; STEPHENS, GRAEME - CALIFORNIA INSTITUTE OF TECHNOLOGY; WOOD, ERIC - PRINCETON UNIVERSITY

Submitted to: Water Resources Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/11/2017
Publication Date: 3/11/2017
Citation: Fisher, J.B., Middleton, E., Melton, F., Anderson, M.C., Hook, S., Hain, C., Allen, R., McCabe, M., Lagouarde, J., Tu, K., Baldocchi, D., Townsend, P.A., Kilic, A., Perret, J., Miralles, D., Waliser, D., French, A.N., Schimel, D., Famiglietti, J., Stephens, G., Wood, E. 2017. The future of evapotranspiration: global requirements for ecosystem functioning, carbon and climate feedbacks, agricultural management, and water resources. Water Resources Research. 53(4):2618-2626. https://doi.org/10.1002/2016WR020175.
DOI: https://doi.org/10.1002/2016WR020175

Interpretive Summary: Forecasting ecosystem health and availability of sufficient water resources to sustain a healthy terrestrial biosphere is becoming increasingly important with global climate change. However, the uncertainties of forecasts are large because the systems and sensors required are inadequate for accurate monitoring of biological and hydrological processes at global scales. One of the key components is the evapotranspiration (ET) process, which links water and carbon fluxes at local to global scales. By expanding ET research and development, it will be possible to answer essential scientific questions about biosphere health such as how much water will be available for different ecosystems over time, how does ET affect the speed of climate change, and how does the spatial distribution of ET affect food production? This commentary advocates for a pathway that will help answer these questions by expanding spaceborne remote sensing capabilities and include deployment of sensors monitoring the global land surface daily, at resolutions under 100 m in the visible, near infrared and thermal infrared. The proposed strategy will be important for research and application scientists in climate change fields, water resource planners and policy makers worldwide.

Technical Abstract: The fate of the terrestrial biosphere is highly uncertain given recent and projected changes in climate, particularly for water resources availability with increases in drought frequency and intensity. Food and water security are under threat from limitations in our understanding of how agricultural systems are responding and should be managed under changing hydrological and climatological regimes, coupled with insufficient monitoring capabilities on a global scale. Here, we describe how evapotranspiration is central to linking ecosystem functioning, carbon and climate feedbacks, agricultural management, and water resources; we outline the key science and applications questions, and the requirements necessary to advance them.