Weakening temperature control on the interannual variations of spring carbon uptake across northern lands

• Published in: Nature Climate Change
• Main Authors: Piao, Shilong, Liu, Zhuo, Wang, Tao, Peng, Shushi, Ciais, Philippe, Huang, Mengtian, Ahlström, Anders, Burkhart, John, Chevallier, Frederic, Janssens, Ivan, Jeong, Su-Jong, Lin, Xin, Mao, Jiafu, Miller, John, Mohammat, Anwar, Myneni, Ranga B., Peñuelas, Josep, Shi, Xiaoying, Zeng, Zhenzhong, Tans, Pieter P.
• Other Authors: Peking University Beijing, Institute of Tibetan Plateau Research, Chinese Academy of Sciences Beijing (CAS), Laboratoire des Sciences du Climat et de l'Environnement Gif-sur-Yvette (LSCE), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), ICOS-ATC (ICOS-ATC), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Lund University Lund, Norwegian Institute for Air Research (NILU), Modélisation INVerse pour les mesures atmosphériques et SATellitaires (SATINV), Department of Biology (University of Antwerp), University of Antwerp (UA), Jet Propulsion Laboratory (JPL), NASA-California Institute of Technology (CALTECH), Climate Change Science Institute Oak Ridge (CCSI), Oak Ridge National Laboratory Oak Ridge (ORNL), UT-Battelle, LLC-UT-Battelle, LLC, National Oceanic and Atmospheric Administration (NOAA), Cooperative Institute for Research in Environmental Sciences (CIRES), University of Colorado Boulder -National Oceanic and Atmospheric Administration (NOAA), Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences Changchun Branch (CAS), Boston University Boston (BU), Centre de Recerca Ecològica i Aplicacions Forestals (CREAF), Centre d'Estudis Avançats de Blanes (CEAB), Consejo Superior de Investigaciones Científicas Madrid (CSIC), NOAA Earth System Research Laboratory (ESRL), European Project: 610028,EC:FP7:ERC,ERC-2013-SyG,IMBALANCE-P(2014)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2017
• Subjects: [SDU.STU.CL]Sciences of the Universe [physics]/Earth Sciences/Climatology; [SDU.OCEAN]Sciences of the Universe [physics]/Ocean; Atmosphere; [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces; environment; Barrow; Alaska
• Online Access: https://hal.archives-ouvertes.fr/hal-01584218; https://hal.archives-ouvertes.fr/hal-01584218/document; https://hal.archives-ouvertes.fr/hal-01584218/file/natclic.pdf; https://doi.org/10.1038/NCLIMATE3277

International audience Ongoing spring warming allows the growing season to begin earlier, enhancing carbon uptake in northern ecosystems. Here we use 34 years of atmospheric CO$_2$ concentration measurements at Barrow, Alaska (BRW, 71° N) to show that the interannual relationship between spring temperature and carbon uptake has recently shifted. We use two indicators: the spring zero-crossing date of atmospheric CO$_2$ (SZC) and the magnitude of CO$_2$ drawdown between May and June (SCC). The previously reported strong correlation between SZC, SCC and spring land temperature (ST) was found in the first 17 years of measurements, but disappeared in the last 17 years. As a result, the sensitivity of both SZC and SCC to warming decreased. Simulations with an atmospheric transport model coupled to a terrestrial ecosystem model suggest that the weakened interannual correlation of SZC and SCC with ST in the last 17 years is attributable to the declining temperature response of spring net primary productivity (NPP) rather than to changes in heterotrophic respiration or in atmospheric transport patterns. Reduced chilling during dormancy and emerging light limitation are possible mechanisms that may have contributed to the loss of NPP response to ST. Our results thus challenge the ‘warmer spring–bigger sink’ mechanism.