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, Ahlstrom, Anders, Burkhart, John F., Chevallier, Frederic, Janssens, Ivan A., Jeong, Su-Jong, Lin, Xin, Mao, Jiafu, Miller, John, Mohammat, Anwar, Myneni, Ranga B., Penuelas, Josep, Shi, Xiaoying, Stohl, Andreas, Yao, Yitong, Zhu, Zaichun, Tans, Pieter P.
• Other Authors: Piao, SL (reprint author), Chinese Acad Sci, Key Lab Alpine Ecol & Biodivers, Inst Tibetan Plateau Res, Beijing 100085, Peoples R China.; Piao, SL (reprint author), Peking Univ, Sinofrench Inst Earth Syst Sci, Coll Urban & Environm Sci, Beijing 100871, Peoples R China.; Piao, SL (reprint author), Chinese Acad Sci, Ctr Excellence Tibetan Earth Sci, Beijing 100085, Peoples R China., Chinese Acad Sci, Key Lab Alpine Ecol & Biodivers, Inst Tibetan Plateau Res, Beijing 100085, Peoples R China., Peking Univ, Sinofrench Inst Earth Syst Sci, Coll Urban & Environm Sci, Beijing 100871, Peoples R China., Chinese Acad Sci, Ctr Excellence Tibetan Earth Sci, Beijing 100085, Peoples R China., CEA CNRS UVSQ, Lab Sci Climat & Environm, F-91191 Gif Sur Yvette, France., Stanford Univ, Sch Earth Energy & Environm Sci, Stanford, CA 94305 USA., Univ Oslo, Dept Geosci, POB 1047 Blindem, N-0316 Oslo, Norway., Univ Antwerp, Dept Biol, Univ Pl 1, B-2610 Antwerp, Belgium., South Univ Sci & Technol China, Sch Environm Sci & Engn, Shenzhen 518055, Peoples R China., Oak Ridge Natl Lab, Climate Change Sci Inst, Oak Ridge, TN 37831 USA., Oak Ridge Natl Lab, Div Environm Sci, POB 2008, Oak Ridge, TN 37831 USA., NOAA, ESRL, 325 Broadway, Boulder, CO 80305 USA., Univ Colorado, Cooperat Inst Res Environm Sci, Boulder, CO 80309 USA., Chinese Acad Sci, Xinjiang Inst Ecol & Geog, Urumqi 830011, Xinjiang, Peoples R China., Boston Univ, Dept Earth & Environm, 675 Commonwealth Ave, Boston, MA 02215 USA., CREAF, Barcelona 08193, Catalonia, Spain., CREAF CEAB CSIC UAB, CSIC, Global Ecol Unit, Barcelona 08193, Catalonia, Spain., NILU Norwegian Inst Air Res, POB 100, N-2027 Kjeller, Norway., Piao, SL (reprint author), Peking Univ, Sinofrench Inst Earth Syst Sci, Coll Urban & Environm Sci, Beijing 100871, Peoples R China., Piao, SL (reprint author), Chinese Acad Sci, Ctr Excellence Tibetan Earth Sci, Beijing 100085, Peoples R China.
• Format: Journal/Newspaper
• Language: English
• Published: NATURE CLIMATE CHANGE 2017
• Subjects: ATMOSPHERIC CO2; FOREST; MODEL; SENSITIVITY; ECOSYSTEMS; LATITUDES; PHENOLOGY; DIOXIDE; BALANCE; SEASON; Barrow; Alaska
• Online Access: https://hdl.handle.net/20.500.11897/469244; https://doi.org/10.1038/NCLIMATE3277

Ongoing spring warming allows the growing season to begin earlier, enhancing carbon uptake in northern ecosystems(1-3). Here we use 34 years of atmospheric CO2 concentration measurements at Barrow, Alaska (BRW, 71 degrees 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 CO2 (SZC) and the magnitude of CO2 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(4) coupled to a terrestrial ecosystem model(5) 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. National Natural Science Foundation of China [41530528]; Chinese Academy of Sciences [131C11KYSB20160061]; BELSPO STEREO project ECOPROPHET [SR00334]; 111 Project [B14001]; National Youth Top-notch Talent Support Program in China; European Research Council [ERC-2013-SyG-610028]; Regional and Global Climate Modeling Program in the CESD of the BER Program in the US Department of Energy Office of Science; DOE [DE-AC05-00OR22725] SCI(E) SSCI ARTICLE 5 359-+ 7