Temperature dependence of spring carbon uptake in northern high latitudes during the past four decades

• Published in: Global Change Biology
• Main Authors: Zhu, Dan, Wang, Yilong, Ciais, Philippe, Chevallier, Frédéric, Peng, Shushi, Zhang, Yao, Wang, Xuhui
• Other Authors: Sino-French Institute for Earth System Science, College of Urban and Environmental Sciences, 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), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Modélisation INVerse pour les mesures atmosphériques et SATellitaires (SATINV), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2024
• Subjects: [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.science/hal-04311945; https://doi.org/10.1111/gcb.17043

Abstract In the northern high latitudes, warmer spring temperatures generally lead to earlier leaf onsets, higher vegetation production, and enhanced spring carbon uptake. Yet, whether this positive linkage has diminished under climate change remains debated. Here, we used atmospheric CO 2 measurements at Barrow (Alaska) during 1979–2020 to investigate the strength of temperature dependence of spring carbon uptake reflected by two indicators, spring zero‐crossing date (SZC) and CO 2 drawdown (SCC). We found a fall and rise in the interannual correlation of temperature with SZC and SCC ( R SZC‐T and R SCC‐T ), showing a recent reversal of the previously reported weakening trend of R SZC‐T and R SCC‐T . We used a terrestrial biosphere model coupled with an atmospheric transport model to reproduce this fall and rise phenomenon and conducted factorial simulations to explore its potential causes. We found that a strong–weak–strong spatial synchrony of spring temperature anomalies per se has contributed to the fall and rise trend in R SZC‐T and R SCC‐T , despite an overall unbroken temperature control on net ecosystem CO 2 fluxes at local scale. Our results provide an alternative explanation for the apparent drop of R SZC‐T and R SCC‐T during the late 1990s and 2000s, and suggest a continued positive linkage between spring carbon uptake and temperature during the past four decades. We thus caution the interpretation of apparent climate sensitivities of carbon cycle retrieved from spatially aggregated signals.