Download - Greenhouse Gas Accounting: NCAS
Greenhouse Gas Accounting: NCAS
Carbon Farming Expo - Orange Nov 2008
Dr Bill Slattery Department of Climate Change
Outline
• Overview of land sector emissions• On-Farm whole system emissions
accounting• National carbon accounting system• Carbon sequestration potential for soils
Australia’s Greenhouse Gas Emissions (2006)
In comparison
Agriculture component of national emissions in other countries
NZ 50%, EU 10%, US 5.5%)
100
150
200
250
300
Mt C
O2-
e
0
50
StationaryEnergy
Transport FugitiveEmissions
IndustrialProcesses
Agriculture Land UseChange and
Forestry
Waste
50%
14%
6% 5%
16%
7%3%
Key Greenhouse Gases from Land-systems
Nitrous Oxide • 4% of Australia’s total emissions • Agricultural soils, savanna burning
and forest soils
Methane• 12% of Australia’s total – almost
same as all of transport • Enteric fermentation from livestock• Savannah burning• Uptake by soils maybe significant
Australia’s National Carbon Accounting
SystemModelling framework
Carbon in soils
NCAS models C fluxes that:• Consider changes in all soil C pools • Soil C change through management practice
Issues:- Permanence- Spatial variability- Validation
Carbon
CO2
Plant production
Photosynthesis
Plant residues
Mineralisation
Soil animals and microbes
Recalcitrant organic C
Particulate organic C
Humus organic C
Burning
Nitrous oxide from soils
Only 30-70% of nitrogen inputs to soil is used by plants – the rest goes missing
• runoff and leaching• nitrous oxide emissions• reducing N2O emissions = improved NUE &
greenhouse benefits For accounting purposes need to focus on the plant-soil-
water-atmosphere interactions
Soil animals and microbes
C & N2O
CO2
Plant production
Photosynthesis
Plant residues
Recalcitrant organic C
Particulate organic C
Humus organic C
Burning
Fertiliser
Organic N
NO3
Mineralisation
NH4
Plant uptake
N2O
Nitrification
Denitrification
Methane from sheep and cattle
10-15% of feed energy lost as methane• Major cost • Focus on Improving Feed Conversion Efficiency
Increase productivity and profitAND reduce methane emissions at the same time
Soil animals and microbes
C, N2O & CH4
CO2
Plant production
Photosynthesis
Plant residues
Recalcitrant organic C
Particulate organic C
Humus organic C
Burning
Fertiliser
NO3
Mineralisation
NH4
Plant uptake
N2O
Nitrification
Denitrification
Organic N
Manure
CH4
Breed
PastureQuality
Urine
National Carbon Accounting System
Remote sensing
15 Landsat images from 1972 - 2006
Spatial datasets- Climate- Soil info- veg cover- landuse- etc
Site specific data
Emissions estimation
How does NCAS work?
The NCAS tracks emissions (sources) and removals (sinks) of greenhouse gases from Australian land based systems.
Integrates satellite remote sensing and ecosystem modelling to provide greenhouse accounts for Agriculture, Land Use and Forestry
Relationship with NGGI
• NGGI is adapted to currently available data ‘streams’– Reflect administrative, not land system
boundaries– Typically use simple ‘emissions factor’
approaches at global/national scales
0%
10%
20%
30%
40%
50%
StationaryEnergy
Transport FugitiveEmissions
IndustrialProcesses
Agriculture Land Use,Change
andForestry
Waste
National Greenhouse Inventory
Accounting methods - UNFCCC
Methods:• Tier 1: ‘activity’ data (crop/livestock)
multiplied by international default factors• Tier 2: ‘activity’ data multiplied by
national default factors• Tier 3: Modelling approach
NGGI uses Tier 2 accounting
What does this mean?• Tier 2: = ‘activity’ data multiplied by national default
factors• This method:
– Simply cannot distinguish between management practice and emissions
– Will only reflect a reduction in methane or nitrous oxide emissions when production is reduced (e.g. livestock numbers)
– We need to have proper accounting that reflects changes in management.
Enabling NCAS to provide emission estimates at:
Farm scale
Regional scale National scale
Soil C has a major role in soil health through– improved soil structure, increased water retention,
increased nutrient cycling, better soil buffering.
Potential to Sequester Soil Carbon
Major role of carbon in soil
For Cropping Soils
• No-till reduces fuel use by 30% • But - remember nitrous oxide emissions from
soil with N-fertiliser 0.5 – 3 tCO2e/ha/yr
“whole systems accounting”
0.1 – 0.2 tCO2e /ha/y
0.003 kgCO2e/ha/yC sequestration
No-till
0.5 – 3 tCO2/ha/y
Nitrous oxide
Finite period ~ 20yrs
Soil C (tC/ha)
Plant biomass (tC/ha)
Stubble burnt
Years1 2 3 4 5 6 7 8 9 10 11 12 1 3 14 15 16 17 18 19 20
1 2 3 4 5 6 7 8 9 10 11 12 1 3 14 15 16 17 18 19 20 Years
Soil C (tC/ha)
Plant biomass (tC/ha)
Stubble standing
This represents a reduced loss not a sequestration
NCAS example model runs
0 20 40 60 80 100Years
C (
t/ha
)
Rutherglen – Standing stubble
Cropping soil – low rainfall (uneven seasonal pattern)
Soil C
Plant Biomass
NCAS example model runs
Mudgee - Standing stubble
Cropping soil – high rainfall (even seasonal pattern)
NCAS example model runs
Pastures (assuming a 1% increase in soil C over 10 years)
Pasture and livestock grazing likely to increase total GHG’s by:@ 0.1 – 1.5 cattle/ha/yr (avg 164kg CH4/animal/yr)
(164 x 21 x 0.1 OR 1.5) 0.3 – 5 t CO2e/ha/yr
@ 3 – 20 sheep/ha/yr (avg 10kg/animal/yr)
(10 x 21 x 3 OR 20) 0.6 – 4 t CO2e/ha/yr
“whole systems accounting”
0.4 tCO2e /ha/y
C sequestration
0.3 – 5 tCO2/ha0.6 – 4 tCO2/ha
0.1leg – 0.3 fert tCO2/ha
MethaneMethane
N inputs
Finite period ~ 20yrs
GREAT NEWS ON
OUR GREENHOUSE TARGETS
WE’VE BRED A COWTHAT DOESN’T RELEASE
ANY METHANE
0 20 40 60 80 100Years
Permanent pasture
Soil C
Plant biomass
NCAS example model runs
0 20 40 60 80 100Years
Permanent pasture
Soil C
Plant biomass
NCAS example model runs
Soil C = 76 t CO2e
Methane = 250 - 500 t CO2e
Nitrous oxide = 30 - 60 tCO2e
N fertiliser or legume pasture
grazing
Net emissions
• Initial soil Carbon level• Environment (rainfall, temp - decomposition rates)• Residue return to soil (Biomass production)• Paddock history (C pool structure)• Soil texture• Soil pH & fertility
Other factors play an important role in determining the amount of C that can be stored in soil:
• All countries are required to report national emissions accounts
• There are still some gaps in knowledge for land based systems
• NCAS provides a wall to wall accounting system for the land sector – All greenhouse gas sources and sinks– All practices– All landuses
• NCAS aims to provide a decision support tool for a range of landscape scales for emissions management and measurement
• NCAS provides a consistent approach to emissions accounting nationally
Concluding Remarks
Thankyou