Contrasting effects of CO₂ fertilization, land-use change and warming on seasonal amplitude of Northern Hemisphere CO₂ exchange

Ana Bastos (1) , Philippe Ciais (2, 3) , Frédéric Chevallier (2, 4) , Christian Rödenbeck (5) , Ashley Ballantyne , Fabienne Maignan (2, 6) , Yi Yin , Marcos Fernández-Martínez , Pierre Friedlingstein (7) , Josep Penuelas (8) , Shilong Piao (9) , Stephen Sitch , William R Smith , Xuhui Wang (9) , Zaichun Zhu (10) , Vanessa Haverd (11) , Etsushi Kato (12) , Atul Jain (13) , Sebastian Lienert (14) , Danica Lombardozzi (15) , Julia Nabel , Philippe Peylin (2, 6) , Benjamin Poulter (16) , Dan Zhu (2)

1 LMU - Ludwig Maximilian University [Munich] = Ludwig Maximilians Universität München
2 LSCE - Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette]
3 ICOS-ATC - ICOS-ATC
4 SATINV - Modélisation INVerse pour les mesures atmosphériques et SATellitaires
5 MPI-BGC - Max-Planck-Institut für Biogeochemie
6 MOSAIC - Modélisation des Surfaces et Interfaces Continentales
7 College of Engineering, Mathematics and Physical Sciences
8 CREAF - Centre de Recerca Ecològica i Aplicacions Forestals
9 Sino-French Institute for Earth System Science, College of Urban and Environmental Sciences
10 Soochow University
11 CSIRO - Commonwealth Scientific and Industrial Research Organisation
12 IAE - Institute of Applied Energy
13 Department of Atmospheric Sciences [Urbana]
14 CEP - Climate and Environmental Physics [Bern]
15 NCAR - National Center for Atmospheric Research [Boulder]
16 MSU - Montana State University

Continuous atmospheric CO 2 monitoring data indicate an increase in the amplitude of seasonal CO 2-cycle exchange (SCA NBP) in northern high latitudes. The major drivers of enhanced SCA NBP remain unclear and intensely debated, with land-use change, CO 2 fertilization and warming being identified as likely contributors. We integrated CO 2-flux data from two atmospheric inversions (consistent with atmospheric records) and from 11 state-of-the-art land-surface models (LSMs) to evaluate the relative importance of individual contributors to trends and drivers of the SCA NBP of CO 2 fluxes for 1980-2015. The LSMs generally reproduce the latitudinal increase in SCA NBP trends within the inversions range. Inversions and LSMs attribute SCA NBP increase to boreal Asia and Europe due to enhanced vegetation productivity (in LSMs) and point to contrasting effects of CO 2 fertilization (positive) and warming (negative) on SCA NBP. Our results do not support land-use change as a key contributor to the increase in SCA NBP. The sensitivity of simulated microbial respiration to temperature in LSMs explained biases in SCA NBP trends, which suggests that SCA NBP could help to constrain model turnover times.

Domaines: Physique Atmosphérique et Océanique [physics.ao-ph]

Ana Bastos, Philippe Ciais, Frédéric Chevallier, Christian Rödenbeck, Ashley Ballantyne, et al.. Contrasting effects of CO₂ fertilization, land-use change and warming on seasonal amplitude of Northern Hemisphere CO₂ exchange. Atmospheric Chemistry and Physics, 2019, 19 (19), pp.12361-12375. ⟨10.5194/acp-19-12361-2019⟩. ⟨hal-02398289⟩