Download - E missions from land use change and soil carbon changes in c arbon footprints of animal products
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!