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Exploratory Workshop: Towards a global synthesis of CH 4 fluxes from land ecosystems Towards a Global Synthesis of Methane Fluxes From Land Ecosystems Report from the ESF Exploratory Workshop held in Hamburg (Germany), 10-12 April 2012 Lars Kutzbach, Miguel Mahecha, Timo Vesala http://www.klimacampus.de/esfworkshopch4.html

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Exploratory Workshop: Towards a global synthesis of CH 4 fluxes from land ecosystems Since the 1980s, hundreds of studies on CH 4 emission from various land ecosystems have been published, mostly based on chamber methods. In the 1990s, the first eddy covariance (EC) measurements of CH 4 fluxes were published; however, few because of expensive and technically demanding instruments; recently, the number of EC studies is strongly increasing due to fast technical development of new trace gas analysers. There is no global synthesis of these extensive datasets so far. Neither, there are generally accepted best practices protocols for chamber and EC methodologies. Recently, many different initiatives focusing on CH 4 were initiated. Stronger links between different networks appear necessary. Motivation for the exploratory workshop

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Exploratory Workshop: Towards a global synthesis of CH 4 fluxes from land ecosystems PERGAMON (COST, EU) GHG-Europe (EU) PAGE21 (EU) ABBA (COST, EU) MethaneNet (NERC, UK) DEFROST (Scandinavia) (KoPF, BMBF, Germany) FLUXNET many smaller projects ICOS (EU) Now many initiatives on CH 4 : need for networking between networks ? InGOS (EU)

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Exploratory Workshop: Towards a global synthesis of CH 4 fluxes from land ecosystems General goals of the exploratory workshop Initiation of a global synthesis activity that aims at harmonizing the steadily increasing number of methane (CH 4 ) measurements from terrestrial ecosystems worldwide and evaluating them jointly Cooperation of scientists with complementary experiences: field measurements, advanced empirical data analyses, remote sensing, mechanistic modeling Setting the stage for following larger-scale international activities (e.g., open science workshop in Hyytil, September 2012)

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Exploratory Workshop: Towards a global synthesis of CH 4 fluxes from land ecosystems A global CH 4 -FLUXNET (or GHG-FLUXNET) could . provide the scientific community with independent empirical reference for: - Local terrestrial CH 4 dynamics - Empirical relations e.g. temperature sensitivities - Up-scaled fluxes AND this initiative could avoid many difficulties by learning from (and being integrated in) the existing (CO 2 -)FLUXNET experience, e.g., Data policy PI involvement Data standardization Reference for constraining diagnostic/predictive models Initiation of a CH 4 -FLUXNET

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Exploratory Workshop: Towards a global synthesis of CH 4 fluxes from land ecosystems Outline of the workshop 2.5 days 8 plenary sessions: 6 topical scientific sessions, 14 scientific talks, 2 summarising discussion sessions 3 time slots (in total 5 hours) for 3 parallel break-out sessions in which subgroups focussed on advancing the specific questions/deliverables

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Exploratory Workshop: Towards a global synthesis of CH 4 fluxes from land ecosystems Outline of the workshop 26 participants from 11 countries (10 European countries, US) 10 females, 16 males 15 young scientists, 11 experienced scientists (according to the ESF definition)

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Exploratory Workshop: Towards a global synthesis of CH 4 fluxes from land ecosystems Outline of the workshop Tuesday, 10.04.12 A. Plenary session: The need for a FLUXNET-CH 4 ; state of the art of land-atmosphere CH 4 flux research (talks Kutzbach, Mahecha, Scarascia- Mugnozza, Heimann) B. Plenary session: CH 4 flux data availability from different land ecosystems (talks Rinne, Oechel, Zona, Schrier) Wednesday, 11.04.12 C. Plenary session: Towards standardized methodologies for CH 4 flux studies (talks Riis Christiansen, Eugster, Dengel) D. Plenary session: Setting up a FLUXNET-CH 4 initiative (talks Papale, Vesala, Sachs, v. Huissteden)

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Exploratory Workshop: Towards a global synthesis of CH 4 fluxes from land ecosystems Outline of the workshop Wednesday, 11.04.12 E. Break-out sessions a) Next steps for the initiation of a FLUXNET-CH 4 initiative b) Joint efforts on best practices for closed chamber CH 4 flux studies c) Joint efforts on best practices for eddy covariance CH 4 flux studies F. Break-out sessions Continuation G. Plenary session: Representation of CH 4 processes in climate-carbon cycle models (talks Heimann, v. Huissteden, Vesala)

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Exploratory Workshop: Towards a global synthesis of CH 4 fluxes from land ecosystems Outline of the workshop Thursday, 12.04.12 H. Plenary session: Global-scale analyses/synthesis of CH 4 processes and fluxes (talks Matthews, Mahecha, Bloom, Bousquet) I. Plenary session: Summary and general discussion of break-out sessions J. Plenary session: General discussion on next steps to achieve the workshop deliverables, follow-up research activities and/or collaborative actions or other specific outputs K. Break-out sessions Continuation

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Exploratory Workshop: Towards a global synthesis of CH 4 fluxes from land ecosystems Outcomes: Next steps for the initiation of a FLUXNET-CH 4 initiative The participants recognised the need for a network of networks for CH 4 research within Europe but preferably also on the global scale: a FLUXNET-CH 4 . This network of networks primarily needs a functional and consistent database and a well-maintained, functional and inspiring information exchange platform. The participants suggested using existing infrastructure to efficiently build up these two basic prerequisites for a global CH 4 synthesis activity.

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Exploratory Workshop: Towards a global synthesis of CH 4 fluxes from land ecosystems Outcomes: Next steps for the initiation of a FLUXNET-CH 4 initiative As information exchange platform, the existing internet platform www.MethaneNet.org (currently funded by the NERC, UK) is suggested. Recommendation to avoid redundant databases and to establish the needed new CH 4 flux database as a part of the already existing European Eddy Fluxes Databases Cluster (www.europe-fluxdata.eu). For long-term archiving, using the open access library PANGAEA (http://www.pangaea.de) should be considered.

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Exploratory Workshop: Towards a global synthesis of CH 4 fluxes from land ecosystems Outcomes: Next steps for the initiation of a FLUXNET-CH 4 initiative Dario Papale agreed to expand the European Eddy Fluxes Databases Cluster so that it fits to the needs of a CH 4 flux synthesis. It was agreed that the new database should include chamber measurements. Database structure and the required content of the metadata information needs to be discussed. Much is already implemented by Dario, but further discussion and optimisation necessary.

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Exploratory Workshop: Towards a global synthesis of CH 4 fluxes from land ecosystems ab Graphic: P. Schreiber Graphic: A. Hormann Outcomes: Best practices for closed chamber CH 4 flux studies

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Exploratory Workshop: Towards a global synthesis of CH 4 fluxes from land ecosystems Outcomes: Best practices for closed chamber CH 4 flux studies In a recent extensive CH 4 flux chamber intercomparison experiment (18 types), the tested chambers differed widely in their performance to replicate a reference flux, suggesting that published estimates of trace-gas fluxes are often biased. Systematic errors derive from saturation of headspace, lack of mixing and disturbance of the headspace. However, these biases can be minimised by applying non-linear regression flux calculation methods, increasing the chamber volume to basal area ratio, sufficient headspace mixing and minimising manual gas sampling volumes.

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Exploratory Workshop: Towards a global synthesis of CH 4 fluxes from land ecosystems Outcomes: Best practices for closed chamber CH 4 flux studies Chamber results are generally considered highly valuable for budget considerations, characterisation of spatial variability across scales, and validation of modelling results. However, it is necessary to develop a strategy to correct or post-calibrate existing chamber data based on metadata information on the experimental set-up. ( New database!) Uncertainty ranges due to different measurement designs have to be assigned to each chamber data set following a standardised approach. Is it possible to recommend the perfect chamber for future research? Yes.

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Exploratory Workshop: Towards a global synthesis of CH 4 fluxes from land ecosystems Outcomes: Best practices for eddy covariance CH 4 flux studies

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Exploratory Workshop: Towards a global synthesis of CH 4 fluxes from land ecosystems Outcomes: Best practices for eddy covariance CH 4 flux studies Currently, many new CH 4 analysers based on laser spectroscopy are made available on the market. Large fluxes can be measured with any of the currently available optical CH 4 analysers. Large fluxes can be measured also with weak pumps (even with high damping losses). Small fluxes are still a challenge making careful instrument selection important. Data processing is still an issue as CH 4 analysers have different properties than CO 2 analysers, and additional or modified correction methods may be needed.

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Exploratory Workshop: Towards a global synthesis of CH 4 fluxes from land ecosystems Outcomes: Best practices for eddy covariance CH 4 flux studies Generally, most principles of flux processing established for EC measurements of CO 2 are also valid for CH 4. Major methodological differences between EC measurements of CH 4 and CO 2 are related to lower flux magnitudes and less or no diurnal variability of CH 4 fluxes as well as to the differences in the instrumentation needed to detect CH 4 concentration quickly and and precisely enough for the EC approach. Need to better understand the impact of the instrument design constraints (flow distortion, sensor heating) on the accuracy of the CH 4 flux measurements.

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Exploratory Workshop: Towards a global synthesis of CH 4 fluxes from land ecosystems Outcomes: Best practices for eddy covariance CH 4 flux studies Impact of advection and storage on the CH 4 fluxes needs to be systematically researched. The effect of density corrections according to the Webb- Pearman-Leuning (WPL) on EC CH 4 flux estimates is not sufficiently investigated. Is density correction better done by the classical WPL term on the fluxes or a point-by-point dilution calculation on the rawdata? The detection of CH 4 ebullition fluxes by the EC methodology needs to be studied in depth. Hot spots and hot moments!!

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Exploratory Workshop: Towards a global synthesis of CH 4 fluxes from land ecosystems Outcomes: Initiation of several collaborative synthesis papers E. Matthews: Meta-data analysis of the existing CH 4 flux literature, development of a methanocentric wetland classification

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Exploratory Workshop: Towards a global synthesis of CH 4 fluxes from land ecosystems E. Matthews: What are wetlands and where are they? papyrus, Uganda Okavango, Botswana Zambezi River, Africa Pantanal, Brazil Sudd Swamp, Sudan Amazon, Brazil Amazon, Peru N. Australia Lake Jipe, Tanzania

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Exploratory Workshop: Towards a global synthesis of CH 4 fluxes from land ecosystems Outcomes: Initiation of several collaborative synthesis papers E. Matthews: Meta-data analysis of the existing CH 4 flux literature, development of a methanocentric wetland classification M. Mahecha et al.: Using new statistical time series analysis methods to extract the temperature sensitivity of ecosystem CH 4 fluxes W. Eugster, J. Rinne, L. Kutzbach et al.: State of the art of CH 4 flux measurements by eddy covariance methodology J. Riis Christiansen, S. Petersen, L. Kutzbach et al.: State of the art of CH 4 flux measurements by closed chamber methodology Many more ideas for papers and projects put forward in Hyytil

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Exploratory Workshop: Towards a global synthesis of CH 4 fluxes from land ecosystems Next steps Largerscale, international open science workshop on The importance of land-atmosphere fluxes of methane and nitrous oxide for the global greenhousegas balance The need for a FLUXNET-GHG Hyytil, Finland 27 September 2012 (95 participants incl. US, Europe, China, Japan, etc.)

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Exploratory Workshop: Towards a global synthesis of CH 4 fluxes from land ecosystems Next steps Working on the database structure for CH 4 fluxes within the European Fluxes Database Cluster (www.europe-fluxdata.eu) Which metadata needs to be included? What needs to be incorporated in addition to the existing CO 2 flux database? If you want to contribute ideas on these questions, please contact Dario Papale (darpap@unitus.it) or Lars Kutzbach (lars.kutzbach@zmaw.de).lars.kutzbach@zmaw.de Much is already implemented, but further discussion and optimisation needed.

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Exploratory Workshop: Towards a global synthesis of CH 4 fluxes from land ecosystems Next steps Working on collaborative synthesis papers either in small groups using CH 4 data from these groups (or from literature reviews) and/or through contributing to the proposed new larger- scale CH 4 database within the European Fluxes Database Cluster (www.europe-fluxdata.eu) Register your site, explore the database structure and provide feedback to Dario Papale (darpap@unitus.it)

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Exploratory Workshop: Towards a global synthesis of CH 4 fluxes from land ecosystems Further need for integration ! Networking between different CH 4 science communities still needs to be intensified measurements experiments models land ocean atmosphere different climate zones different continents Other CH 4 flux database initiatives ? European? Global?

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Exploratory Workshop: Towards a global synthesis of CH 4 fluxes from land ecosystems of field researchers and modellers International teamwork needed German Russian Slovakian

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Exploratory Workshop: Towards a global synthesis of CH 4 fluxes from land ecosystems Thank you for your attention ! More information on the ESF Exploratory workshop (e.g., programme, list of participants, presentations): http://www.klimacampus.de/esfworkshopch4.html Email: lars.kutzbach@zmaw.de More information on the ESF Exploratory workshop (e.g., programme, list of participants, presentations): http://www.klimacampus.de/esfworkshopch4.html Email: lars.kutzbach@zmaw.de Photo: H. Joosten

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Exploratory Workshop: Towards a global synthesis of CH 4 fluxes from land ecosystems

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Objectives of a CH 4 -FLUXNET: To provide a solid basis for a global quantification of the natural spatial and temporal (seasonal to interannual) variability of natural CH 4 -effluxes

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Exploratory Workshop: Towards a global synthesis of CH 4 fluxes from land ecosystems Objectives of a CH 4 -FLUXNET: e.g. via upscaling fluxes (even if this sounds now too early for CH 4 ) To provide a solid basis for a global quantification of the natural spatial and temporal (seasonal to interannual) variability of natural CH 4 -effluxes Example from CO2-fluxes to be adapted

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Exploratory Workshop: Towards a global synthesis of CH 4 fluxes from land ecosystems Objectives of a CH 4 -FLUXNET: Jung et al. (2010) Nature. 467: 951-954. Monitoring of relationships between drivers and fluxes at site level! Machine Learning of relationships between drivers and fluxes Applying algorithm to gridded variables: generating a quasi observational flux field e.g. via upscaling fluxes (even if this sounds now too early for CH 4 ) To provide a solid basis for a global quantification of the natural spatial and temporal (seasonal to interannual) variability of natural CH 4 -effluxes Exploratory Workshop: Towards a global Synthesis of CH 4 fluxes from land ecosystems

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Exploratory Workshop: Towards a global synthesis of CH 4 fluxes from land ecosystems Objectives of a CH 4 -FLUXNET: To provide a solid basis for a global quantification of the natural spatial and temporal (seasonal to interannual) variability of natural CH 4 -effluxes Why this works? Monitoring of relationships between drivers and fluxes at site level! Machine Learning of relationships between drivers and fluxes Applying algorithm to gridded variables: generating a quasi observational flux field

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Exploratory Workshop: Towards a global synthesis of CH 4 fluxes from land ecosystems Objectives of a CH 4 -FLUXNET: Sampling of the climate space less dense! More drivers needed (wetland extend?) How to deal with regime shifts? How to deal with the much higher spatiotemporal resolution (heterogeneity!) To provide a solid basis for a global quantification of the natural spatial and temporal (seasonal to interannual) variability of natural CH 4 -effluxes Complications in case of CH 4 fluxes Monitoring of relationships between drivers and fluxes at site level! Machine Learning of relationships between drivers and fluxes Applying algorithm to gridded variables: generating a quasi observational flux field

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Exploratory Workshop: Towards a global synthesis of CH 4 fluxes from land ecosystems Objectives of a CH 4 -FLUXNET: Help constraining terrestrial biosphere models -FLUXNET = becoming the reference for structural adjustments or parameter optimization of terrestrial biosphere models. -Are similar approaches thinkable for a CH 4 initiative? ( At least for specific regions?) M. Williams et al. (2009) Improving land surface models with FLUXNET data. Biogeosciences, 6: 1341-1359. Data could be either eddy-covariance, chamber, or upscaled data!

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Exploratory Workshop: Towards a global synthesis of CH 4 fluxes from land ecosystems Objectives of a CH 4 -FLUXNET: Help constraining terrestrial biosphere models -FLUXNET = becoming the reference for structural adjustments or parameter optimization of terrestrial biosphere models. -Are similar approaches thinkable for a CH 4 initiative? ( At least for specific regions?) Suzuki & Iichi (2011) Evaluation of a terrestrial carbon cycle submodel in an earth system model using FLUXNET observations. Tellus B, ?: xxx-yyy. (CHECK REF, IS PUBLISHED)

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Exploratory Workshop: Towards a global synthesis of CH 4 fluxes from land ecosystems Expected deliverables The seed for an international CH 4 -FLUXNET initiative which builds on and connects previous synthesis and networking activities. Open science (!) workshop in Hyytil, Finland 2-7 September 2012 The importance of land-atmosphere fluxes of methane and nitrous oxide for the global greenhouse-gas balance The need for a FLUXNET-GHG ( Sigrid Dengel) A strategy for the implementation of a functional and consistent database collecting CH 4 flux measurements from the global land ecosystems applying different approaches, e.g. chamber and eddy covariance methods. Papers on recommendations on best practices in chamber and eddy covariance applications for CH 4 flux measurements and standardized protocols for data processing and quality control.

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Exploratory Workshop: Towards a global synthesis of CH 4 fluxes from land ecosystems Expected deliverables 4. Initialization of a series of synthesis papers on different aspects of CH4 flux processes, for instance on the temperature sensitivity of CH 4 5. Strategy for the generation of scaled up CH 4 fields, a quasi-observational space- time explicit picture, at least for the northern temperate to arctic latitudes.