GHG Inventory methods used by Annex 1 countries

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Inventorying Agricultural Soil Greenhouse Gas
Emissions Methods Used by Annex 1 Countries
Erandi Lokupitiya and Keith Paustian Colorado
State University
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Global commitment towards mitigating greenhouse
gas emissions

• Adoption of the United Nations Framework
  Convention on Climate Change (UNFCCC) in 1992
• Adoption of the Kyoto) Protocol in 1997 (Ratified
  and implemented Feb 2005
• Member countries are expected to submit national
  GHG inventories prepared using comparable
  methodologies (IPCC revised guidelines and Good
  Practice Guidance)
• Annual submissions are made by Annex 1
  (developed) countries

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Major GHG sectors under the UNFCCC/Kyoto Protocol
Energy
Industrial processes
Solvent and other product use
Waste
Agriculture
Land-Use Change and forestry
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Source/sink categories under the agricultural
sector
Manure management
Enteric fermentation
Rice cultivation
Agricultural soils
Burning of agricultural residues
Prescribed burning of savannas
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IPCC inventory methodology

• Tier 1- simple equations and default emission
  factors
• Tier 2- default equations with country-specific
  parameters that better account for climate, soil,
  management and other local conditions
• Tier 3- country-specific methods that may include
  more complex models and inventory systems

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IPCC inventory methodology contd..

• Estimation of N2O emissions from agricultural
  soils
• direct N2O emissions from agricultural soils
• 2) direct soil emissions of N2O from animal
  production (livestock grazing)
• 3) indirect emissions of N2O from N used in
  agriculture (losses from N volatilization and
  leaching)

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IPCC inventory methodology contd..

• Estimation of direct N2O emissions
• N2O DIRECT (kg N/yr) FSN FAW FCR FBN
  EF1 FOS EF2
• FSN N input from synthetic fertilizer use
• FAW N from livestock manure applied to soil
• FBN total N input in N-fixing crops
• FCR N input from crop residues
• FOS Area of cultivated Organic Soils
• EF1 Emission factor for emissions from N inputs
• EF2 Emission factor for emissions from organic
  soil cultivation

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Evaluation of IPCC default methodology for N2O
estimation

• Universal, and allows comparability among the
  national estimates by different countries
• Likely statistical bias in data - for N2O. Most
  studies have been done in temperate countries
• Method does not reflect variation among different
  crops, soils and climates that can influence N2O
  production

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IPCC inventory methodology contd..

• Estimation of emissions/ removals of CO2 from
  agricultural soils
• 1) Changes in C stored in mineral soils due to
  changes in land-use practices
• 2) Cultivated organic soils
• 3) Liming of agricultural soils

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IPCC inventory methodology contd..

• Estimation of changes in mineral soil C stocks
• ?SC (SCt SC(t-D) A/D
• SCi SCR FLU FMG FI
• ?SC annual SOC stock change
• SCt SOC stock at time t
• SC(t-D) SOC stock at time t-20 years
• SCR reference carbon stock
• FLU, FMG, FI stock change factors for LU and
  management
• D Duration (default is 20 years).

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Evaluation of IPCC methodology for estimation of
CO2 emissions

• allows comparability among countries
• Takes into account the spatial variability
  associated with soil type, climate and management
  regime.
• Relatively high uncertainty in global default
  stock change and emission factors

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CORINAIR (CORe INventory of AIR emissions in
Europe) methodology- European Union

• Includes an improved methodology for N2O based on
  multivariate regression analyses incorporating
  climate, weather and soil conditions, etc.
• No alternative methodology suggested for
  estimating CO2 emissions. But higher emission
  factors compared to IPCC has been suggested for
  CO2 released from cultivated organic soils
• can be transformed to IPCC format based on the
  information in the Annex 2 of the Volume 1 of
  revised IPCC guidelines

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Country specific methods developed by certain
Annex1 countries
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• Australia
• National Carbon Accounting System (NCAS)
• A model-based accounting system, based on
  resource inventories, field studies, remote
  sensing and modeling
• Full C Accounting Model (FullCAM) for estimating
  land use change emissions associated with biomass
  and soil C pools
• Five component models 3PG (forest growth),
  CAMFor (forest systems), CAMAg (agricultural
  systems), GENDEC (microbial decomposition),
  Roth-C (agricultural soil C)
• Requirement of time-series consistency in
  estimating GHG from land use change is well met
  by NCAS

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Results from NCAS
Source Australian Greenhouse Office
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AustriaAustrian Carbon Balance Model (ACBM)

• Model covers five national subsystems including
  agriculture
• Agricultural soil C dynamics are estimated using
  a three pool model.
• Net emissions from agricultural soil using the
  ACBM was 13 lower than estimates made using the
  IPCC default method

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• Canada
• National C and Greenhouse gas emission
  Accounting and Verification System for
  agriculture (NCGAVS)

• Estimates soil C change and direct N2O emissions
  from agricultural soils
• Model-based system using integrated databases of
  information on climate, land use change and
  management
• Basic geographic units are Soil Landscapes of
  Canada (SLC) polygons
• CENTURY based estimates showed an overall CO2
  loss of 7.08 Mt. in 1990, and a net sink of 0.5
  Mt in 2002

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Germany

• Using two dynamic models for estimating NO and
  N2O emissions
• - Denitrification and Decomposition (DNDC)
  model (for agricultural soils)
• - Photosynthesis and Evapotranspiration-
  Nitrification- Denitrification and Decomposition
  (PnET-N-DNDC) model (for forest soils)
• Better estimates from multi-year simulations at
  regional scale
• Consistent with IPCC default (ag soil estimates
  only 10 higher compared to IPCC)

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New ZealandCarbon Monitoring System (CMS)

• to estimate C stock changes due to land cover
  changes, based on a simple empirical model,
  similar in concept to the IPCC Tier 1 approach
• Soil C estimated for land cover/use categories in
  18 different soil-climate classes
• more detailed breakdown of climate zones, and
  inclusion of an erosivity index compared to IPCC
  method
• encouraging results at local site scale, but
  sometimes overestimated the observed soil C at
  regional scale, due to variation in local factors
  such as stoniness and slope
• Major data gaps need to be filled before
  efficient operation

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CMS and IPCC GPG/default soil C values (t C ha-1,
top 30cm) for arable soils (Tate et al., 2002,
IPCC GPG, 2003)
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SwedenIntroductory Carbon Balance Model (ICBM)

• a two pool model calibrated using long-term field
  data, incorporated into a regional framework to
  estimate changes in soil C
• Conceptually simple can be run and optimized in
  a conventional spreadsheet program
• Input data- agricultural statistics, daily
  weather data, climate region, soil type, crop
  type, etc.
• This model approach is still in the testing
  phase, and currently only the emissions from
  organic soils are reported in the NIR.

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United States

• a Tier2 versopm of the IPCC methodology with
  US-specific reference C stocks and stock change
  factors
• (11 Tg for mineral soils and -9 Tg for organic
  soils)
• Dynamic approach using CENTURY model
• (23 Tg for mineral soils)
• incorporates information from National Resources
  Inventory (NRI) data on land use, crop type,
  irrigation, pasture management, soil type, etc.,
  and tillage information
• For estimating N2O emissions, a simulation based
  approach using the DAYCENT model is being
  developed.
• DayCent estimates are about 10 lower than those
  with IPCC default method

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Conclusions

• Currently, less comprehensive reporting of GHG
  emissions and methods for soils
• IPCC default methodology still mostly being used-
  simple with default emission and stock change
  factors
• Country-specific methods, usually process-based
  models, are being rapidly developed in several
  Annex1 countries.
• Simulation models with detailed activity data are
  used in most country-specific methods.
• One constraint for fully utilization of
  country-specific methods is the lack of
  comprehensive national databases.

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Acknowledgements

• National Greenhouse Offices
• Consortium for Agricultural Soils Mitigation of
  Greenhouse Gases (CASMGS) for financial support