title: The uncertain climate footprint of wetlands under human pressure.
abstract: Significant climate risks are associated with a positive carbon-temperature feedback in northern latitude carbon-rich ecosystems, making an accurate analysis of human impacts on the net greenhouse gas balance of wetlands a priority. Here, we provide a coherent assessment of the climate footprint of a network of wetland sites based on simultaneous and quasi-continuous ecosystem observations of CO2 and CH4 fluxes. Experimental areas are located both in natural and in managed wetlands and cover a wide range of climatic regions, ecosystem types, and management practices. Based on direct observations we predict that sustained CH4 emissions in natural ecosystems are in the long term (i.e., several centuries) typically offset by CO2 uptake, although with large spatiotemporal variability. Using a space-for-time analogy across ecological and climatic gradients, we represent the chronosequence from natural to managed conditions to quantify the "cost" of CH4 emissions for the benefit of net carbon sequestration. With a sustained pulse-response radiative forcing model, we found a significant increase in atmospheric forcing due to land management, in particular for wetland converted to cropland. Our results quantify the role of human activities on the climate footprint of northern wetlands and call for development of active mitigation strategies for managed wetlands and new guidelines of the Intergovernmental Panel on Climate Change (IPCC) accounting for both sustained CH4 emissions and cumulative CO2 exchange.
authors.affiliation: European Commission, Joint Research Center, Institute for Environment and Sustainability, Ispra (VA) 21027, Italy;
authors.forename: Ana Maria Roxana
authors.initials: AM
authors.lastname: Petrescu
authors.affiliation: Atmospheric Composition Research, Finnish Meteorological Institute, FI-00101 Helsinki, Finland;
authors.forename: Annalea
authors.initials: A
authors.lastname: Lohila
authors.affiliation: Atmospheric Composition Research, Finnish Meteorological Institute, FI-00101 Helsinki, Finland;
authors.forename: Juha-Pekka
authors.initials: JP
authors.lastname: Tuovinen
authors.affiliation: Department of Environmental Science, Policy, and Management, University of California, Berkeley, CA 94720;
authors.forename: Dennis D
authors.initials: DD
authors.lastname: Baldocchi
authors.affiliation: Atmospheric & Oceanic Sciences Department, University of Wisconsin-Madison, Madison, WI 53706;
authors.forename: Ankur R
authors.identifier: http://orcid.org/0000-0002-5226-6041
authors.initials: AR
authors.lastname: Desai
authors.affiliation: Department of Geography & the Global Environmental and Climate Change Research Centre, McGill University, Montreal, QC H3A 2K6, Canada;
authors.forename: Nigel T
authors.initials: NT
authors.lastname: Roulet
authors.affiliation: Departments of Physics and Forest Sciences, University of Helsinki, FIN-00014 Helsinki, Finland;
authors.forename: Timo
authors.initials: T
authors.lastname: Vesala
authors.affiliation: Department of Earth Sciences, Earth and Climate Cluster, VU University Amsterdam, 1081 HV Amsterdam, The Netherlands;
authors.forename: Albertus Johannes
authors.initials: AJ
authors.lastname: Dolman
authors.affiliation: Global Change Research Group, Department of Biology, San Diego State University, San Diego, CA 92182;
authors.forename: Walter C
authors.initials: WC
authors.lastname: Oechel
authors.affiliation: Sustainable Agro-ecosystems and Bioresources Department, Fondazione Edmund Mach, 1 I-38010 S. Michele all'Adige (TN), Italy;
authors.forename: Barbara
authors.initials: B
authors.lastname: Marcolla
authors.affiliation: CENter for PERMafrost, Department of Geosciences and Natural Resource Management, University of Copenhagen,1350 K Copenhagen, Denmark;
authors.forename: Thomas
authors.initials: T
authors.lastname: Friborg
authors.affiliation: Atmospheric Composition Research, Finnish Meteorological Institute, FI-00101 Helsinki, Finland; Departments of Physics and Department of Geosciences and Geography, University of Helsinki, FIN-00014 Helsinki, Finland;
authors.forename: Janne
authors.initials: J
authors.lastname: Rinne
authors.affiliation: Department of Environmental Science, Policy, and Management, University of California, Berkeley, CA 94720;
authors.forename: Jaclyn Hatala
authors.initials: JH
authors.lastname: Matthes
authors.affiliation: Department of Environmental Systems Science, Institute of Agricultural Sciences, ETH Zurich, 8092 Zurich, Switzerland;
authors.forename: Lutz
authors.initials: L
authors.lastname: Merbold
authors.affiliation: European Commission, Joint Research Center, Institute for Environment and Sustainability, Ispra (VA) 21027, Italy;
authors.forename: Ana
authors.initials: A
authors.lastname: Meijide
authors.affiliation: Civil and Environmental Engineering Department and Environmental Research Institute, University College Cork, Cork, Ireland;
authors.forename: Gerard
authors.initials: G
authors.lastname: Kiely
authors.affiliation: Civil and Environmental Engineering Department and Environmental Research Institute, University College Cork, Cork, Ireland;
authors.forename: Matteo
authors.initials: M
authors.lastname: Sottocornola
authors.affiliation: Helmholtz Centre Potsdam (GFZ) (Geoforschungszentrum) German Research Centre for Geosciences, Department of Inorganic and Isotope Geochemistry, 14473 Potsdam, Germany;
authors.forename: Torsten
authors.initials: T
authors.lastname: Sachs
authors.affiliation: Global Change Research Group, Department of Biology, San Diego State University, San Diego, CA 92182; Department of Animal and Plant Sciences, University of Sheffield, Sheffield S10 2TN, United Kingdom;
authors.forename: Donatella
authors.initials: D
authors.lastname: Zona
authors.affiliation: A. N. Severtsov Institute of Ecology and Evolution, Russian Academy of Sciences, Moscow 119071, Russia;
authors.forename: Andrej
authors.initials: A
authors.lastname: Varlagin
authors.affiliation: Department of Geography and Resource Management, The Chinese University of Hong Kong, Hong Kong SAR, China;
authors.forename: Derrick Y F
authors.initials: DY
authors.lastname: Lai
authors.affiliation: Nature Conservation and Plant Ecology Group, Wageningen University, 6700 AA Wageningen, The Netherlands;
authors.forename: Elmar
authors.initials: E
authors.lastname: Veenendaal
authors.affiliation: Department of Physical Geography and Ecosystem Science, Lund University, SE-223 62 Lund, Sweden; Arctic Research Centre, Department of Bioscience, Aarhus University, DK-4000 Roskilde, Denmark;
authors.forename: Frans-Jan W
authors.initials: FJ
authors.lastname: Parmentier
authors.affiliation: Centre for Ecology and Hydrology, Bush Estate, Penicuik EH26 0QB, United Kingdom;
authors.forename: Ute
authors.initials: U
authors.lastname: Skiba
authors.affiliation: Department of Physical Geography and Ecosystem Science, Lund University, SE-223 62 Lund, Sweden; Arctic Research Centre, Department of Bioscience, Aarhus University, DK-4000 Roskilde, Denmark;
authors.forename: Magnus
authors.initials: M
authors.lastname: Lund
authors.affiliation: Energy Research Centre of the Netherlands (Energieonderzoek Centrum Nederland), Environmental Research, 1755 ZG Petten, The Netherlands;
authors.forename: Arjan
authors.initials: A
authors.lastname: Hensen
authors.affiliation: Department of Earth Sciences, Earth and Climate Cluster, VU University Amsterdam, 1081 HV Amsterdam, The Netherlands;
authors.forename: Jacobus
authors.initials: J
authors.lastname: van Huissteden
authors.affiliation: Department of Biological Sciences, University of Lethbridge, Lethbridge, AB T1K 3M4, Canada;
authors.forename: Lawrence B
authors.initials: LB
authors.lastname: Flanagan
authors.affiliation: Department of Environmental Science, University of Eastern Finland, FIN-70211 Kuopio, Finland;
authors.forename: Narasinha J
authors.initials: NJ
authors.lastname: Shurpali
authors.affiliation: Institute of Hydrology and Meteorology, Chair of Meteorology, Technische Universität Dresden, D-01062 Dresden, Germany;
authors.forename: Thomas
authors.initials: T
authors.lastname: Grünwald
authors.affiliation: Department of Geography and Environmental Studies, Carleton University, Ottawa, ON K1S 5B6, Canada;
authors.forename: Elyn R
authors.initials: ER
authors.lastname: Humphreys
authors.affiliation: Department of Physical Geography and Ecosystem Science, Lund University, SE-223 62 Lund, Sweden;
authors.forename: Marcin
authors.initials: M
authors.lastname: Jackowicz-Korczyński
authors.affiliation: Atmospheric Composition Research, Finnish Meteorological Institute, FI-00101 Helsinki, Finland;
authors.forename: Mika A
authors.initials: MA
authors.lastname: Aurela
authors.affiliation: Atmospheric Composition Research, Finnish Meteorological Institute, FI-00101 Helsinki, Finland;
authors.forename: Tuomas
authors.initials: T
authors.lastname: Laurila
authors.affiliation: European Commission, Joint Research Center, Institute for Environment and Sustainability, Ispra (VA) 21027, Italy;
authors.forename: Carsten
authors.initials: C
authors.lastname: Grüning
authors.affiliation: Laboratory of Forest Ecology, Department of Forest, Environment, and Resources, University of Tuscia of Viterbo, 01100 Viterbo, Italy; and.
authors.forename: Chiara A R
authors.initials: CA
authors.lastname: Corradi
authors.affiliation: Nature Conservation and Plant Ecology Group, Wageningen University, 6700 AA Wageningen, The Netherlands;
authors.forename: Arina P
authors.initials: AP
authors.lastname: Schrier-Uijl
authors.affiliation: Department of Physical Geography and Ecosystem Science, Lund University, SE-223 62 Lund, Sweden; Arctic Research Centre, Department of Bioscience, Aarhus University, DK-4000 Roskilde, Denmark;
authors.forename: Torben R
authors.initials: TR
authors.lastname: Christensen
authors.affiliation: Arctic Research Centre, Department of Bioscience, Aarhus University, DK-4000 Roskilde, Denmark;
authors.forename: Mikkel P
authors.initials: MP
authors.lastname: Tamstorf
authors.affiliation: Department of Physical Geography and Ecosystem Science, Lund University, SE-223 62 Lund, Sweden; Arctic Research Centre, Department of Bioscience, Aarhus University, DK-4000 Roskilde, Denmark;
authors.forename: Mikhail
authors.initials: M
authors.lastname: Mastepanov
authors.affiliation: Department of Environmental Science, University of Eastern Finland, FIN-70211 Kuopio, Finland;
authors.forename: Pertti J
authors.initials: PJ
authors.lastname: Martikainen
authors.affiliation: School of Natural Resources, University of Nebraska-Lincoln, Lincoln, NE 68583.
authors.forename: Shashi B
authors.initials: SB
authors.lastname: Verma
authors.affiliation: Institute of Hydrology and Meteorology, Chair of Meteorology, Technische Universität Dresden, D-01062 Dresden, Germany;
authors.forename: Christian
authors.initials: C
authors.lastname: Bernhofer
authors.affiliation: European Commission, Joint Research Center, Institute for Environment and Sustainability, Ispra (VA) 21027, Italy; alessandro.cescatti@jrc.ec.europa.eu.
authors.forename: Alessandro
authors.initials: A
authors.lastname: Cescatti
mesh_terms: D002245:Carbon Dioxide / Q000378:metabolism; D002980:Climate; D057231:Climate Change; D004463:Ecology / Q000379:methods; D017753:Ecosystem; D005843:Geography; D006802:Human Activities; D006801:Humans; D008697:Methane / Q000378:metabolism; D008962:Models, Theoretical; D009609:Nitrous Oxide / Q000378:metabolism; D010944:Plants / Q000145:classification / Q000378:metabolism; D013696:Temperature; D035501:Uncertainty; D053833:Wetlands
chemical_list: D002245:Carbon Dioxide; D009609:Nitrous Oxide; D008697:Methane
keywords: carbon dioxide; methane; radiative forcing; wetland conversion
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