title: Compensatory water effects link yearly global land CO2sink changes to temperature.
abstract: Large interannual variations in the measured growth rate of atmospheric carbon dioxide (CO2) originate primarily from fluctuations in carbon uptake by land ecosystems. It remains uncertain, however, to what extent temperature and water availability control the carbon balance of land ecosystems across spatial and temporal scales. Here we use empirical models based on eddy covariance data and process-based models to investigate the effect of changes in temperature and water availability on gross primary productivity (GPP), terrestrial ecosystem respiration (TER) and net ecosystem exchange (NEE) at local and global scales. We find that water availability is the dominant driver of the local interannual variability in GPP and TER. To a lesser extent this is true also for NEE at the local scale, but when integrated globally, temporal NEE variability is mostly driven by temperature fluctuations. We suggest that this apparent paradox can be explained by two compensatory water effects. Temporal water-driven GPP and TER variations compensate locally, dampening water-driven NEE variability. Spatial water availability anomalies also compensate, leaving a dominant temperature signal in the year-to-year fluctuations of the land carbon sink. These findings help to reconcile seemingly contradictory reports regarding the importance of temperature and water in controlling the interannual variability of the terrestrial carbon balance. Our study indicates that spatial climate covariation drives the global carbon cycle response.
authors.affiliation: Department of Biogeochemical Integration, Max Planck Institute for Biogeochemistry, 07745 Jena, Germany.
authors.forename: Martin
authors.initials: M
authors.lastname: Jung
authors.affiliation: Department of Biogeochemical Integration, Max Planck Institute for Biogeochemistry, 07745 Jena, Germany.|Michael-Stifel-Center Jena for Data-driven and Simulation Science, Friedrich-Schiller-Universität Jena, 07743 Jena, Germany.
authors.forename: Markus
authors.initials: M
authors.lastname: Reichstein
authors.affiliation: Woods Hole Research Center, 149 Woods Hole Road, Falmouth, Massachusetts 02540, USA.
authors.forename: Christopher R
authors.initials: CR
authors.lastname: Schwalm
authors.affiliation: Centre for Ecology and Hydrology, Wallingford, Oxfordshire OX10 8BB, UK.
authors.forename: Chris
authors.initials: C
authors.lastname: Huntingford
authors.affiliation: College of Life and Environmental Sciences, University of Exeter, Exeter EX4 4QF, UK.
authors.forename: Stephen
authors.initials: S
authors.lastname: Sitch
authors.affiliation: Department of Earth System Science, School of Earth, Energy and Environmental Sciences, Stanford University, Stanford, California 94305, USA.|Department of Physical Geography and Ecosystem Science, Lund University, 223 62 Lund, Sweden.
authors.forename: Anders
authors.initials: A
authors.lastname: Ahlström
authors.affiliation: Karlsruhe Institute of Technology, Institute of Meteorology and Climate Research, 82467 Garmisch-Partenkirchen, Germany.
authors.forename: Almut
authors.initials: A
authors.lastname: Arneth
authors.affiliation: Image Processing Laboratory, Universitat de València, Catedrático José Beltrán, Paterna 46980, València, Spain.
authors.forename: Gustau
authors.initials: G
authors.lastname: Camps-Valls
authors.affiliation: Laboratoire des Sciences du Climat et de l'Environnement, CEA CNRS UVSQ, 91191 Gif-sur-Yvette, France.
authors.forename: Philippe
authors.initials: P
authors.lastname: Ciais
authors.affiliation: College of Engineering, Mathematics and Physical Sciences, University of Exeter, Exeter EX4 4QE, UK.
authors.forename: Pierre
authors.initials: P
authors.lastname: Friedlingstein
authors.affiliation: Department of Biogeochemical Integration, Max Planck Institute for Biogeochemistry, 07745 Jena, Germany.
authors.forename: Fabian
authors.initials: F
authors.lastname: Gans
authors.affiliation: Department of Environment Geochemical Cycle Research, Japan Agency for Marine-Earth Science and Technology, 3173-25, Showa-machi, Kanazawa-ku, Yokohama 236-0001, Japan.|Center for Global Environmental Research, National Institute for Environmental Studies, 16-2 Onogawa, Tsukuba, 305-8506, Japan.
authors.forename: Kazuhito
authors.initials: K
authors.lastname: Ichii
authors.affiliation: Department of Atmospheric Sciences, University of Illinois, Urbana, Illinois 61801, USA.
authors.forename: Atul K
authors.initials: AK
authors.lastname: Jain
authors.affiliation: Global Environment Program, The Institute of Applied Energy, Tokyo 105-0003, Japan.
authors.forename: Etsushi
authors.initials: E
authors.lastname: Kato
authors.affiliation: Department for Innovation in Biological, Agro-food and Forest systems, University of Tuscia, 01100 Viterbo, Italy.
authors.forename: Dario
authors.initials: D
authors.lastname: Papale
authors.affiliation: NASA Goddard Space Flight Center, Biospheric Science Laboratory, Greenbelt, Maryland 20771, USA.
authors.forename: Ben
authors.initials: B
authors.lastname: Poulter
authors.affiliation: Department for Innovation in Biological, Agro-food and Forest systems, University of Tuscia, 01100 Viterbo, Italy.|Department of Bioengineering, Sapientia Hungarian University of Transylvania, 530104 M-Ciuc, Romania.
authors.forename: Botond
authors.initials: B
authors.lastname: Raduly
authors.affiliation: Max Planck Institute for Biogeochemistry, Department of Biogeochemical Systems, 07745 Jena, Germany.
authors.forename: Christian
authors.initials: C
authors.lastname: Rödenbeck
authors.affiliation: Department for Innovation in Biological, Agro-food and Forest systems, University of Tuscia, 01100 Viterbo, Italy.
authors.forename: Gianluca
authors.initials: G
authors.lastname: Tramontana
authors.affiliation: Laboratoire des Sciences du Climat et de l'Environnement, CEA CNRS UVSQ, 91191 Gif-sur-Yvette, France.
authors.forename: Nicolas
authors.initials: N
authors.lastname: Viovy
authors.affiliation: CSIRO Oceans and Atmosphere, PMB #1, Aspendale, Victoria 3195, Australia.
authors.forename: Ying-Ping
authors.initials: YP
authors.lastname: Wang
authors.affiliation: Department of Biogeochemical Integration, Max Planck Institute for Biogeochemistry, 07745 Jena, Germany.
authors.forename: Ulrich
authors.initials: U
authors.lastname: Weber
authors.affiliation: Department of Biogeochemical Integration, Max Planck Institute for Biogeochemistry, 07745 Jena, Germany.|Michael-Stifel-Center Jena for Data-driven and Simulation Science, Friedrich-Schiller-Universität Jena, 07743 Jena, Germany.
authors.forename: Sönke
authors.initials: S
authors.lastname: Zaehle
authors.affiliation: Institute of Atmospheric Physics, Chinese Academy of Science, Beijing 100029, China.|Department of Atmospheric and Oceanic Science, University of Maryland, College Park, Maryland 20742, USA.
authors.forename: Ning
authors.initials: N
authors.lastname: Zeng
mesh_terms: D001272:Atmosphere / Q000737:chemistry; D057486:Carbon Cycle; D002245:Carbon Dioxide / Q000032:analysis / Q000378:metabolism*; D019069:Cell Respiration; D017753:Ecosystem; D000069550:Machine Learning; D010788:Photosynthesis; D013696:Temperature; D014867:Water / Q000032:analysis / Q000378:metabolism*
chemical_list: D014867:Water; D002245:Carbon Dioxide