Disentangling climatic and anthropogenic controls on global terrestrial evapotranspiration trends

Wednesday, 16 December 2015: 15:25
3022 (Moscone West)
Jiafu Mao1, Wenting Fu2, Xiaoying Shi1, Daniel M Ricciuto1, Joshua B Fisher3, Robert E Dickinson2, Yaxing Wei1, Willis Shem1, Shilong Piao4, Kaicun Wang5, Christopher R Schwalm6, Hanqin Tian7, Mingquan Mu8, Muhammad Altaf Arain9, Philippe Ciais10, Robert B Cook1, Yong Jiu Dai5, Daniel J Hayes11, Forrest M. Hoffman12, Maoyi Huang13, Suo Huang9, Deborah N Huntzinger14, Akihiko Ito15, Atul K Jain16, Anthony W King1, Huimin Lei17, Chaoqun Lu18, Anna M Michalak19, Nicholas Parazoo20, Changhui Peng21, Shushi Peng10, Benjamin Poulter22, Kevin M Schaefer23, Elchin E Jafarov24, Peter E Thornton1, Weile Wang25, Ning Zeng26, Zhenzhong Zeng4, Fang Zhao26, Qiuan Zhu27 and Zaichun Zhu4, (1)Oak Ridge National Laboratory, Oak Ridge, TN, United States, (2)University of Texas at Austin, Austin, TX, United States, (3)NASA Jet Propulsion Laboratory, Pasadena, CA, United States, (4)Peking University, Beijing, China, (5)Beijing Normal University, Beijing, China, (6)Federal GEOS Funding, Phoenix, AZ, United States, (7)Auburn University at Montgomery, Montgomery, AL, United States, (8)University of California Irvine, Irvine, CA, United States, (9)McMaster University, School of Geography and Earth Sciences, Hamilton, ON, Canada, (10)LSCE Laboratoire des Sciences du Climat et de l'Environnement, Gif-Sur-Yvette Cedex, France, (11)University of Maine, Orono, ME, United States, (12)University of California Irvine, Department of Earth System Science, Irvine, CA, United States, (13)Pacific Northwest National Laboratory, Atmospheric Sciences and Global Change Division, Richland, WA, United States, (14)Northern Arizona University, Flagstaff, AZ, United States, (15)NIES National Institute of Environmental Studies, Ibaraki, Japan, (16)University of Illinois at Urbana Champaign, Urbana, IL, United States, (17)Tsinghua University, Beijing, China, (18)Iowa State University, Ames, IA, United States, (19)Carnegie Institution for Science Washington, Washington, DC, United States, (20)NASA Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, United States, (21)University of Quebec at Montreal UQAM, Montreal, QC, Canada, (22)Montana State University, Bozeman, MT, United States, (23)University of Colorado, National Snow and Ice Data Center, Boulder, CO, United States, (24)Institute of Arctic and Alpine Research, Boulder, CO, United States, (25)CSUMB & NASA/AMES, Seaside, CA, United States, (26)University of Maryland College Park, College Park, MD, United States, (27)Northwest A&F University, college of forestry, Yangling, China
We examined natural and anthropogenic controls on terrestrial evapotranspiration (ET) changes from 1982-2010 using multiple estimates from remote sensing-based datasets and process-oriented land surface models. A significant increased trend of ET in each hemisphere was consistently revealed by observationally-constrained data and multi-model ensembles that considered historic natural and anthropogenic drivers. The climate impacts were simulated to determine the spatiotemporal variations in ET. Globally, rising CO2 ranked second in these models after the predominant climatic influences, and yielded decreased trends in canopy transpiration and ET, especially for tropical forests and high-latitude shrub land. Increased nitrogen deposition slightly amplified global ET via enhanced plant growth. Land-use-induced ET responses, albeit with substantial uncertainties across the factorial analysis, were minor globally, but pronounced locally, particularly over regions with intensive land-cover changes. Our study highlights the importance of employing multi-stream ET and ET-component estimates to quantify the strengthening anthropogenic fingerprint in the global hydrologic cycle.