Articles | Volume 16, issue 8
Atmos. Chem. Phys., 16, 5243–5262, 2016
https://doi.org/10.5194/acp-16-5243-2016

Special issue: Pan-Eurasian Experiment (PEEX)

Atmos. Chem. Phys., 16, 5243–5262, 2016
https://doi.org/10.5194/acp-16-5243-2016

Research article 27 Apr 2016

Research article | 27 Apr 2016

Future vegetation–climate interactions in Eastern Siberia: an assessment of the competing effects of CO2 and secondary organic aerosols

Almut Arneth1, Risto Makkonen2, Stefan Olin3, Pauli Paasonen2, Thomas Holst3, Maija K. Kajos2, Markku Kulmala2, Trofim Maximov4, Paul A. Miller3, and Guy Schurgers3,5 Almut Arneth et al.
  • 1Karlsruhe Institute of Technology, Institute of Meteorology and Climate Research/Atmospheric Environmental Research, Garmisch Partenkirchen, Germany
  • 2Department of Physics, University of Helsinki, P.O. Box 64, 00014 Helsinki, Finland
  • 3Department of Physical Geography and Ecosystem Science, Lund University, Sölvegatan 12, 22362 Lund, Sweden
  • 4Department of Plant Ecological Physiology and Biochemistry Lab., Institute for Biological Problems of Cryolithozone SB RAS, 41, Lenin ave, Yakutsk 677980, Russia
  • 5Department of Geosciences and Natural Resource Management, University of Copenhagen, Øster Voldgade 10, 1350 Copenhagen, Denmark

Abstract. Disproportional warming in the northern high latitudes and large carbon stocks in boreal and (sub)arctic ecosystems have raised concerns as to whether substantial positive climate feedbacks from biogeochemical process responses should be expected. Such feedbacks occur when increasing temperatures lead, for example, to a net release of CO2 or CH4. However, temperature-enhanced emissions of biogenic volatile organic compounds (BVOCs) have been shown to contribute to the growth of secondary organic aerosol (SOA), which is known to have a negative radiative climate effect. Combining measurements in Eastern Siberia with model-based estimates of vegetation and permafrost dynamics, BVOC emissions, and aerosol growth, we assess here possible future changes in ecosystem CO2 balance and BVOC–SOA interactions and discuss these changes in terms of possible climate effects. Globally, the effects of changes in Siberian ecosystem CO2 balance and SOA formation are small, but when concentrating on Siberia and the Northern Hemisphere the negative forcing from changed aerosol direct and indirect effects become notable – even though the associated temperature response would not necessarily follow a similar spatial pattern. While our analysis does not include other important processes that are of relevance for the climate system, the CO2 and BVOC–SOA interplay serves as an example for the complexity of the interactions between emissions and vegetation dynamics that underlie individual terrestrial processes and highlights the importance of addressing ecosystem–climate feedbacks in consistent, process-based model frameworks.

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We study the potentially contrasting effects of enhanced ecosystem CO2 release in response to warmer temperatures vs. emissions of biogenic volatile organic compounds and their formation of secondary organic aerosol through a combination of measurements and modelling at a remote location in Eastern Siberia. The study aims to highlight the number of potentially opposing processes and complex interactions between vegetation physiology, soil processes and trace-gas exchanges in the climate system.
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