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