title: Multi-decadal trends in global terrestrial evapotranspiration and its components.
abstract: Evapotranspiration (ET) is the process by which liquid water becomes water vapor and energetically this accounts for much of incoming solar radiation. If this ET did not occur temperatures would be higher, so understanding ET trends is crucial to predict future temperatures. Recent studies have reported prolonged declines in ET in recent decades, although these declines may relate to climate variability. Here, we used a well-validated diagnostic model to estimate daily ET during 1981-2012, and its three components: transpiration from vegetation (Et), direct evaporation from the soil (Es) and vaporization of intercepted rainfall from vegetation (Ei). During this period, ET over land has increased significantly (p < 0.01), caused by increases in Et and Ei, which are partially counteracted by Es decreasing. These contrasting trends are primarily driven by increases in vegetation leaf area index, dominated by greening. The overall increase in Et over land is about twofold of the decrease in Es. These opposing trends are not simulated by most Coupled Model Intercomparison Project phase 5 (CMIP5) models, and highlight the importance of realistically representing vegetation changes in earth system models for predicting future changes in the energy and water cycle.
authors.affiliation: CSIRO Land and Water, GPO Box 1666, Canberra ACT 2601, Australia.
authors.forename: Yongqiang
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: CSIRO Land and Water, GPO Box 1666, Canberra ACT 2601, Australia.
authors.forename: Jorge L
authors.initials: JL
authors.lastname: Peña-Arancibia
authors.affiliation: CSIRO Land and Water, GPO Box 1666, Canberra ACT 2601, Australia.|ARC Centre of Excellence for Climate System Science &Climate Change Research Centre, University of New South Wales, Sydney 2052, Australia.
authors.forename: Tim R
authors.initials: TR
authors.lastname: McVicar
authors.affiliation: CSIRO Land and Water, GPO Box 1666, Canberra ACT 2601, Australia.
authors.forename: Francis H S
authors.initials: FH
authors.lastname: Chiew
authors.affiliation: CSIRO Land and Water, GPO Box 1666, Canberra ACT 2601, Australia.
authors.forename: Jai
authors.initials: J
authors.lastname: Vaze
authors.affiliation: Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China.
authors.forename: Changming
authors.initials: C
authors.lastname: Liu
authors.affiliation: CSIRO Ocean and Atmosphere, PMB #1, Aspendale, Victoria 3195, Australia.
authors.forename: Xingjie
authors.initials: X
authors.lastname: Lu
authors.affiliation: CSIRO Land and Water, GPO Box 1666, Canberra ACT 2601, Australia.
authors.forename: Hongxing
authors.initials: H
authors.lastname: Zheng
authors.affiliation: CSIRO Ocean and Atmosphere, PMB #1, Aspendale, Victoria 3195, Australia.
authors.forename: Yingping
authors.initials: Y
authors.lastname: Wang
authors.affiliation: ARC Centre of Excellence for Climate System Science &Climate Change Research Centre, University of New South Wales, Sydney 2052, Australia.
authors.forename: Yi Y
authors.initials: YY
authors.lastname: Liu
authors.affiliation: Department of Earth Sciences, VU University Amsterdam, Amsterdam 1081 HV, The Netherlands.|Laboratory of Hydrology and Water Management, Department of Forest and Water Management, Ghent University, B-9000 Ghent, Belgium.
authors.forename: Diego G
authors.initials: DG
authors.lastname: Miralles
authors.affiliation: Department of Civil and Environmental Engineering, Princeton University, NJ 08544, USA.
authors.forename: Ming
authors.initials: M
authors.lastname: Pan