title: Enhanced seasonal CO2 exchange caused by amplified plant productivity in northern ecosystems.
abstract: Atmospheric monitoring of high northern latitudes (above 40°N) has shown an enhanced seasonal cycle of carbon dioxide (CO2) since the 1960s, but the underlying mechanisms are not yet fully understood. The much stronger increase in high latitudes relative to low ones suggests that northern ecosystems are experiencing large changes in vegetation and carbon cycle dynamics. We found that the latitudinal gradient of the increasing CO2 amplitude is mainly driven by positive trends in photosynthetic carbon uptake caused by recent climate change and mediated by changing vegetation cover in northern ecosystems. Our results underscore the importance of climate-vegetation-carbon cycle feedbacks at high latitudes; moreover, they indicate that in recent decades, photosynthetic carbon uptake has reacted much more strongly to warming than have carbon release processes.
authors.affiliation: Max Planck Institute for Biogeochemistry, 07745 Jena, Germany. matthias.forkel@geo.tuwien.ac.at ncarval@bgc-jena.mpg.de.
authors.forename: Matthias
authors.initials: M
authors.lastname: Forkel
authors.affiliation: Max Planck Institute for Biogeochemistry, 07745 Jena, Germany. CENSE, Departamento de Ciências e Engenharia do Ambiente, Faculdade de Ciências e Tecnologia, Universidade NOVA de Lisboa, Caparica, Portugal. matthias.forkel@geo.tuwien.ac.at ncarval@bgc-jena.mpg.de.
authors.forename: Nuno
authors.initials: N
authors.lastname: Carvalhais
authors.affiliation: Max Planck Institute for Biogeochemistry, 07745 Jena, Germany.
authors.forename: Christian
authors.initials: C
authors.lastname: Rödenbeck
authors.affiliation: Scripps Institution of Oceanography, La Jolla, CA 92093, USA.
authors.forename: Ralph
authors.initials: R
authors.lastname: Keeling
authors.affiliation: Max Planck Institute for Biogeochemistry, 07745 Jena, Germany. Department of Physical Sciences, University of Helsinki, Helsinki, Finland.
authors.forename: Martin
authors.initials: M
authors.lastname: Heimann
authors.affiliation: Potsdam Institute for Climate Impact Research, 14473 Potsdam, Germany.
authors.forename: Kirsten
authors.initials: K
authors.lastname: Thonicke
authors.affiliation: Max Planck Institute for Biogeochemistry, 07745 Jena, Germany.
authors.forename: Sönke
authors.initials: S
authors.lastname: Zaehle
authors.affiliation: Max Planck Institute for Biogeochemistry, 07745 Jena, Germany. Michael-Stifel-Center Jena for Data-driven and Simulation Science, 07743 Jena, Germany.
authors.forename: Markus
authors.initials: M
authors.lastname: Reichstein
mesh_terms: D001272:Atmosphere; D057486:Carbon Cycle; D002245:Carbon Dioxide / Q000378:metabolism*; D057231:Climate Change; D017753:Ecosystem; D004784:Environmental Monitoring; D010788:Photosynthesis; D010944:Plants / Q000378:metabolism*; D012621:Seasons
chemical_list: D002245:Carbon Dioxide