Presentation on theme: "Tools for quantifying GHG emissions from Agroecosystems"— Presentation transcript:
1Tools for quantifying GHG emissions from Agroecosystems E. Pattey, R.L. Desjardins and W. SmithAgriculture and Agri-Food Canada, Research Branch, OttawaCAgM Expert Team Meetingon the Contribution of Agriculture to the State of ClimateOttawa, Canada, September 2004
2INTRODUCTIONGoals:Develop a set of reliable Models for estimating net GHG emissions from agricultural sources/sinks and for deriving emissions factors relevant of a given country situation.Establish a series of databases of the various agricultural activities for integrating the GHG emissions over space and time domains (land use, mgt practices, animal production, climate…) .
3INTRODUCTION (Cont’d) A “reliable” Model is:sensitive to input conditions such as management practices;adapted to the geographical and climatic conditions under which it will be used;based on sound scientific knowledge.…Ideally it requires a set of input descriptors easily available.Framework:Any national GHG emission accounting system needs to be transparent (well-documented), verifiable (pilot test sites, scaling-up experiments etc.) and consistent with the Kyoto Protocol.
4OUTLINESpeaker more familiar with Canadian situation Example of Canada…GHG emission estimates from agricultural sources in Canada, CO2, CH4, N2OTools for developing models (chamber, tower)Tools for verifying temporal dynamic and top-down constraints (tower, aircraft)Results from tower- aircraft-based measuring systemsModeling results from Ecosys, DNDC and DaycentSummary
5Greenhouse Gas Emissions from Canada’s Agroecosystems (100 Year Time Horizon - Tg of CO2 equivalents)19811986199119962001CO28752CH42219202324N2O2730283840We are targeting 16 Mt CO2 eq of reduction in 2008We promised to reduce CO2 by 11Mt ( C sequestration) and reached 5-6We promised to reduce CH4 by 4-5 Mt and we do not have any reductionWe promised to reduce N2O by 1 Mt and our emissions increased by 12 MtBFE impact 15$per cow because CDN is not allowed to export in USTotal5756536364
6Atmospheric Inversion GHG flux measuring techniques only cover a limited portion of the space and time domainsArea m2110102103104105106107108109ChamberAircraftBLS&Tracer1MassBalance10Atmospheric InversionTime hTower102Backward Lagrangian Stochastic techniqueSoilCoresSatellite103Regional and sub-continental estimates using tall towers and CBL budgets104
7Benchmark Sites Inventory/ Monitoring Sites Proposed Framework for a Accounting/Verification SystemRegional/ NationalEstimatesRegional Flux andSurface FeatureMeasurementsVerificationScaling UpModel Refinementclimatesoilstopographyland uselandmanagementData collectionRegional (Spatial)databasesAuditing/ MonitoringProcess Studies“Ecosystem Models”Research NeedsDriving variablesModel RefinementVerificationVerificationLong Term Experimental Sites: Flux, Meteorological and Ancillary MeasurementsFGHGBenchmark Sites Inventory/ Monitoring SitesDCs
8How do we improve and verify models? Regional & Nat’l GHG budget(with uncertainty estimates)Verifying temporal dynamicTop-Down constraintMeasuring towers, blimps aircraftModelingVirtual Farm(with uncertainty estimates)Measuring chambers, towersDeveloping new knowledge on mgt practicestime
9Non-Flow Through, Non-Steady State Chamber Measurements Fg = dC V Mw dt A MvExperimental design for comparing management practices and environmental conditions
11Setup for quantifying N2O fluxes for two management practices 1 TDL connected to 2 micromet. towers
12Meas. modelUrea applied at the following rates:Non-linear increase of N2O emissions with fertilizer application rateECOSYSGrant, R. and Pattey, E., Modelling variability in N2O emissions from fertilized agricultural fields. Soil Biology and Biochemistry:35(2):
13Flux Towers are the only suitable measuring approach … during Snow melt (Permanent Site, Ottawa)
15The global Fluxnet project features towers tracking the movement of carbon dioxide between various ecosystems and the air with emphasis on forestEstablish a network of towers for measuring N2O fluxes to verify temporal dynamics of models and assist in scaling up from individual agricultural fields to regionBiocapEurofluxAmerifluxJapanflux
26Schematic of the major components of the DNDC modelEcological driversClimateSoilVegetationAnthropogenicactivityDecompositionCrop GrowthSoil ClimateSoil environmental factorsTemperatureMoisturepHAnaerobicballoonSubstrates(NH4+, NO3- and DOC)DenitrificationNitrificationN Gas EmissionsFluxes of NO, N2O, N2 and NH3Exchange of NOand N2OEffect of temperature and moisture on decomposition
27Using models for obtaining regional and national estimates Regional & Nat’l GHG budget(with uncertainty estimates)MeasuringModelingtime
28Cumulative net GHG emissions Challenge: The net impact of management practices changes with time2040608010012345Time (years)Cumulative C (T ha-1)Cumulative CO2-C from N fertilizer(50 kg N ha-1)Soil C gainNet gainOption AtimeCumulative net GHG emissionsOption AOption BOption C
29Estimated Direct N2O-N Emissions from Agriculture Soils in Canada Using DNDC (1970-1999) 90Estimated direct annual N2O-N emissions80Estimated direct spring N2O-N emissions706050Gg N2O-N40302010197019721974197619781980198219841986198819901992199419961998Year
30National C and GHG Accounting and Verification System “Situations” defined by:SoilClimateLand useManagementcountryprovince“Model”regionSLC polygonSOC & GHGEmissions for each“situation”
31Verification by direct measurement of national GHG estimates best done through holistic top-down national, continental, or global scale GHG budgetsN2O emissions?
32Scientific uncertainty 80Relativeuncertainty(estimated)6040(Mt CO2 equiv. per year)GHG emission20-20-40CO2CH4N2O
34Tools to quantify uncertainties Sensitivity tests of modelsMonte-Carlo approach for evaluating uncertainty
35SummaryTools for measuring GHG fluxes only cover a limited portion of the space and time domainsThe combination of tower and aircraft-based GHG flux measurements provide valuable information to estimate regional fluxes on a daily basisModels are essential for deriving national estimates of GHG emissionsModels still require lots of verification and improvement to provide more accurate estimates