Emissions from land use change and soil carbon changes in carbon footprints of

animal products

Christel Cederberg and Stefan Wirsenius Department of Energy and Environment, Chalmers

SIK, the Swedish Institute for Food and Biotechnology,

KSLA 24 May 2013

Chalmers University of Technology

Increased competition over land

Production of livestock products

- ~75% of global agricultural land - FAO:s global meat consumption to double by 2050

New climate policies? – more expensive to emit fossil CO2

...will lead to increased demand for biomass for energy production

Outline

• CO2-emissions from Land Use Change – case Brazilian beef

• Emissions/sequestration from Land Use • Including land-related emissions and

sequestration in GHG estimates of animal products

Land use impacts Transformation impacts Occupation impacts

Land use change (LUC) – emissions of CO2

CO2 emissions from fossil fuels and Land Use Change, LUC

Data

sour

ces:

Marla

nd e

t al.

(200

7) fo

r fos

sil fu

el us

e an

d Ho

ughto

n (20

08) f

or la

nd us

e cha

nge.

0

2

4

6

8

10

1850 1900 1950 2000

Glob

al CO

2 emi

ssion

s(Gt

C/yr

)

Land use change - the tropicsLand use change - rest of the worldFossil fuel use & cement manufacture

Calculating C emissions from LUC – case Brazilian beef

CH4 CO2

N2O

MATERIALS - Diesel - Fertiliser - (Pesticides) - (Medicine)

FEED - Mineral feed - Comple-mentary feed

BEEF

CO2

Feed Manure

BEEF LIVESTOCK

PASTURE LAND

NATIVE FOREST

Land use change: pasture expansion

Source: Cederberg et al 2011. Env Sc & Tech 45:1773-1779

Typical cycles of land use after deforestation in the Brazilian Amazon

Based on figures in: Ramankutty et al (2007) Global Change Biology 13, 51-66

Year 1 Year 2 Year 3 Year 4

PASTURE

+ + + ......?

........?

GHG emissions caused by Direct Land Use Change

CO2 over several years

After x years are some of the land abadonned – regrowth of forest mostly

Amazon forest transformed to pasture

• Total LUC emissions 612 ± 212 ton CO2e/ha • High uncertainty! Mostly due to uncertainties

in carbon content of the original forest • Distributing 6% of biomass to timber products

removed before burning the forest • Distributing emissions from agriculture

products (beef) 572 ± 198 ton CO2e/ha • Amortize emissions over 20 years

Export

Beef export mostly from non-deforestation states

0

2 000

4 000

6 000

8 000

10 000

1997 1999 2001 2003 2005

1 00

0 to

n CW

E

Total productionDomestic consumptionExports

GHG emissions from Brazilian beef and EU beef

2011-04-01

EU Sweden Brazil LUC

no LUC Total Amazon Direct 20 yrs

CO2 from fossil fuels

3.3 2.2 0.3

Methane (CH4) 10.1 12.5 21.6

Nitrous oxide (N2O)

9.1 5.1 6.3

LUC - - - 44 180 726

Total 22.5 19.8 28.2 72 208 754

System boundary? Total: LUC emissions distributed total beef production Amazon: LUC emissions distributed over beef production in Amazon region Direct 20 yrs: LUC emissions only on beef production on the pastureland deforested the last 20 yrs

Carbon credit for biofuels versus carbon emissions from land use change

Growing feedstock for biofuels remove CO2 from atmosphere

Growing feedstock for biofuels means a direct and/or indirect carbon cost

By excluding LUC-emissions, analyses of biofuels are one-sided because they used only the carbon benefits of using land but not the carbon costs by diverting land from its existing use (Searchinger et al 2008)

Economic equilibrium modelling to estimate indirect land use change from biofuels

Increased demand, crop A

Reduced demand, crop A

Intensified production, crop A

Cultivation of crop A on previous non-agricult land

Crop A replaces crop B

Reduced demand crop B

Intensified production crop B

Cultivation of crop B on previous non-agr land

Crop B replaces crop C

Etc…………

Price increase

Estimates of indirect land use emissions from biofuels vary wildly

Reference Year LUC impact, gram CO2e/MJ fuel

Net impact of biofuel consumption when incl LUC, g CO2e/MJ

Searchinger et al 2008 156-270 127 to 232

EPA (US Renew Fuel Standard 2009 106-130 41 to 52

CARB (California Low Carb Fuel Standard

2009 44-68 15 to -13

Tyner 2009 36 8

EPA final 2010 8-54 -4 to -69

Hertel et al 2010 40 10

Tyner et al 2010 21-32 1 to -9

IFPRI (EU comm) 2010 17 -43

European Commission 2010. The impact of land use change on greenhouse gas emissions from biofuels and bioliquids. Literature review

Important problems with data and methodology when assessing LUC

• D: Areas deforested and initial Carbon stock

• D: land use after LUC • M: Amortisation period • M: DLUC ok with above data but • M: ILUC – requires complex

modelling including land use and trade of agr and biofuel products

Land use impacts Transformation impacts Occupation impacts

Land use (LU) CO2-emissions/C-sequestration?

Verifying soil carbon changes

BASELINE Arable land, stock

75 ton C/ha (0-25 cm)

25 cm ACTION We do a new management activity, positive for C-seq binding 400 kg C/ha*yr. We do this for 25 yrs

Time factor important!

Efter ett år är ökningen 0,5%, dvs mycket liten,

svårt att mäta med jordprov

After 25 yrs C-stock has increased by 10 ton C/ha to

85 ton C/ha. This can be measured

400 kg C/ha*yr = ca 1,5 ton CO2/ha*yr.

Diesel 80l/ha emits ca 250 kg CO2/ha *yr

C-TOOL – 3-pooled dynamic soil carbon model

Important parameters for estimating soil carbon changes

• Carbon input – crop residues – Organic material (e.g. manure)

• Initial carbon stock in soil • Temperature • Clay content • Water content • Carbon/Nitrogen ratio • Tillage(?)

Carbon in harvest products and crop residues

-8

-6

-4

-2

0

2

4

6

C in harvest

C in crop residues

Ton C/ha

Dairy case study - Västra Götaland region

Baseline

Maize & grass

More grass

Kg DM per cow*yr Grass/clover silage, pasture 3 367 1 601 4 499

Maize silage 549 Super-pressed pulp 427

Grain 1 409 1 582 876

Concentrates 1 314 1 383 645

Total 6 090 5 542 6 020

-

- Comparison three feed rations for dairy cows producing 9000 kg milk/yr - Soil carbon changes for the three rations were estimated using C tool

Feed rations according to Liljeholm et al, 2009

Milk and beef can be produced with different feed rations…..effects on soil carbon changes?

0,00

0,10

0,20

0,30

0,40

0,50

0,60

0,70

0,80

Baseline Maize & grass More&BetterGrass

kg D

M fe

ed p

er k

g m

ilk

Concentrates

Grain

Super-pressed pulp

Maize silage

Grass/clover silage, pasture

Production level 9000 kg milk/cow*year

Wirsenius & Cederberg, ”Soil carbon sequestration as a greenhouse gas mitigation option in dairy production”, manus in prep

Land occupation, m2 per kg milk and year

0

0,2

0,4

0,6

0,8

1

1,2

1,4

1,6

1,8

Base Maize More grass

Sce I Sce II Sce III

m2

per k

g m

ilk a

nd y

ear

Other

By-prod sugar industry

Soymeal

Rapeseed meal

Grain

Maize

Grassland

Experiences from modelling soil C changes for different feed rations in milk production

• Initial soil carbon status is very important for the soil´s carbon sequestration potential

• The estimated soil carbon changes are significant, but not of great importance for milk´s total GHG balance

• Feed rations with maize seem to loose soil carbon • Feed rations with maize tend to have lower land

requirement – how is “surplus” land used? • Reasonably correct data on crop residues from

grasslands needed – lack of data!

Thank you!