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Understanding carbon footprints in order to meet the challenge of
sustainable intensification
Gareth Edwards-Jones
Bangor University U.K.
Contact: [email protected]
Structure
• Introduction• Basics• Carbon footprint of foods• Can you lock up carbon on your farm?• Supply chain efficiencies• Farmer knowledge• Conclusion
What is ‘sustainable intensification’?
• We need more food every year from now until 2050.
• The climate is changing, traditional patterns of food production will change.
• All sectors required to reduce GHG emissions from now onwards.
‘Sustainable intensification’ is about producing more food with fewer GHG emissions
Basics
Greenhouse Gases (GHGs)
– Nitrous oxide (N2O) : 1kg = 296 kg CO2-eq/kg
– Methane (CH4): 1 kg = 23 kg CO2-eq/kg
– Others include CFCs, halons, methyl bromide, sulphur hexafluoride, halogenated HC, mono/di/trichloromethane…)
So to get the whole picture we really need to talk about GLOBAL WARMING POTENTIAL (GWP).
The units are CO2 equivalents (kg or tonnes)
Carbon footprint
The amount of greenhouse gases that a given system may release over a specified time period.
The system can be anything from a household to a farm or factory.
LCA in the food system
Farm
Transport
Storage & processing
Retail
INPUTS OUTPUTS
MachineryPesticidesFertiliserEnergy
FoodWastesPollution
MachineryFuel
MachineryElectricity
Pollution
WastesPollution
ElectricityPackaging
WastesPollution
PROCESS
ElectricityFuel
WastesPollutionConsumer
Humus
or
organic matter
or
soil organic carbon
MICROBIAL COMMUNITY
Plant material
Fertiliser(organic and inorganic)
Nitrous oxideMethane
Carbon dioxide
Example carbon footprint of foods
Typical carbon
footprints (various sources)
Item Kg CO2 eq / kg
Apples 0.5
Strawberries 0.8
Green beans 1.4
Broccoli 1.9
Potato 0.64
Tomatoes 2-5
Pork 3-6
Beef 12-23
Milk (per litre) 1
Cheese 7 -13
Chocolate 3.45
C H4 m anure
m anagem ent1 .5%N2O ind irect
9 .0%
inputs22 .0%
N2O d irect
23 .8%
C H4 ente ric
fe rm enta tion43 .7%
GHG emissions from a Welsh beef and lamb farm (Edwards-Jones et al 2009)
Sources of emissions from a conventional dairy farm
C H4 e n te r ic
fe rme n ta tio n3 9 %
in p u ts2 9 %
N2O in d ire c t
6 %
C H4 ma n u re
ma n a g e me n t7 %
C O 2 fro m lime
a p p lica tio n2 %
N2O d ire c t
1 7 %
(Plassmann & Edwards-Jones 2009)
Carbon sequestration
• Soils store huge amounts of carbon.
• Carbon is added every year through the addition of plant material to the soil.
• Continuous arable systems tend to lose carbon.
• Grassland soils tend to sequester carbon – up to some equilibrium point.
Time
Soil carbon
Grass
Plough Plough
Cereals Grass Grass
Patterns of sequestration
How much carbon does grassland lock-up?
• Grassland soils sequester 0.04 - 0.44 t C/Ha/yr• This is equal to 0.15 – 1.62 t CO2eq/Ha/yr
• A sheep emits 8kg of methane a year.• This is equal to 184 KgCO2eq/sheep/yr
• Worst case 1.2 Ha locks up the methane from 1 sheep• Best case 0.1 Ha locks up the methane from 1 sheep
Cows and carbon
• A dairy cow emits about 100 kg/methane/yr• This is equal to 2300 KgCO2eq/cow/yr
• Worst case you need 15 Ha of grass to lock up the methane from 1 cow.
• Best case you need 1.5 Ha of grass to lock up the methane from 1 cow.
Warning
• These figures do not account for any losses of carbon from cultivation.
• Also some people do not think that grassland over 30 years old sequesters any carbon at all.
How much carbon do woodlands lock up?
• Mixed broadleafed woodland in SW Wales locks up 0.67-4.8 tC/Ha/yr
• This is 4.8 – 17.6 tCO2eq/Ha/yr
• This will lock up methane from 2 - 7 dairy cows a year or 13 - 95 sheep a year.
Individual trees• 120 stand alone trees lock up 2.2 tC/yr or 8 tCOe/yr.
• This locks up the methane from 1-3 cows or 5- 18 sheep.
So at best case over a year
114 trees = 1 cow’s methane and
24 trees = 1 sheep’s methane
BUT....• Methane is only 40% of the farm footprint.
• So really the figures are about:
3 Ha of grassland per cow 0.2 – 2.5 Ha of grassland per sheep
or 250 trees per cow 52 trees per sheep.
Questions
• Does this help produce more or just enable us to carry on as we are?
• Can you plant enough trees to genuinely expand production?
• At what scale should we do the sums – farm, county, country?
We need to look further!
Supply chain efficiency
g CO2e / kg potatoes
N2O
CO2
CH4
100
Cultivation
Transport to processing
Packing company
Packaging system
Distribution
Retailer
Transport to home
Household
0 50
GWP of Swedish organic potatoes (Mattson & Wallen 2003)
Navel citrus - 0.4 CO2 eq / kg
Transport refrigeration comprises 45% of transport emissions and 25% of the total navel citrus footprint
IDENTIFYING GREENHOUSE GAS EFFICIENCIES IN FOOD SUPPLY CHAINS THROUGH THE USE
OF KNOWN TECHNOLOGIES
PURPOSE • To scope the reductions in greenhouse gas (GHG)
emissions that could be made across food supply chains through the introduction of good practice and known technologies.
• Funded by Welsh Assembly Government
• Work done by my colleague Rachel Taylor
Methods
• Analyse supply chains for: lamb meat, liquid milk, cheese, fresh strawberries and fresh potatoes.
• Construct a model of each supply chain using information on the GHG emissions from typical farms and supply chains
• Potential interventions to the food chains were formulated with the aim of reducing GHG emissions.
• The impact of introducing these measures was estimated by altering the supply chain models.
Interventions for lamb
-5
0
5
10
15
20
25
30
35
Standardised carbon footprint (kg CO2e / kg lamb consumed
Food preparation
Consumer storage
Transport to consumer
Retail (storage)
Transport to retail
Process and packing
Slaughter waste
Slaughter
Transport to slaughter
On-farm
Liquid milk
-0.5
0.0
0.5
1.0
1.5
2.0
Standardised carbon footprint (kg CO2e / litre milk consumed
Food preparation
Consumer storage
Transport to consumer
Retail (storage)
Transport to retail
Packaging
Dairy processing
Transport to dairy
On-farm
GHG footprints (thousand-tonnes CO2e per year) for Welsh annual consumption of lamb, milk, cheese, strawberries and potatoes. Blue striped bars (baseline data)
represent current emissions; red bars represent best case.
-136%
-32%
-55%
-42%
-54%
-50.0
0.0
50.0
100.0
150.0
200.0
250.0
300.0
Lamb meat Liquid milk Cheese Strawberries PotatoesCarbon footprint in 1000 tonnes CO2e / annual consumption for Wales
Baseline data
Best case scenario
Can farming skill make a difference?
0
5,000
10,000
15,000
20,000
25,000
1 2 3 4 5 6 7 8 9 10 11
Fa rm num be r
kg C
O2
equ
ival
ents
ha
-1 y
ear-1
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
2.0
kg C
O2 eq
uivalen
ts l-1 m
ilk
total direc t inputs total indirec t inputs total N2O
total CH4 CO2 from lime application kg CO2 equivalents per litre m ilk
Average carbon footprint of 11 dairy farms expressed as kg CO2e ha-1 year-1 and kg CO2e l-1 milk
(Plassmann & Edwards-Jones submitted)
y = -0 .0 0 0 1 x + 2 .1 7 0 6
R 2 = 0 .7 2 8 7
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
2.0
4,000 5,000 6,000 7,000 8,000 9,000
M ilk yie ld (l ye a r -1)
kg
CO 2
eq
uiv
ale
nts
l-1 m
ilk
Real data let you do stats!(Plassmann & Edwards-Jones submitted)
y = 6 E -0 6 x + 0 .9 9 2
R 2 = 0 .4 9 4 8
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0 20,000 40,000 60,000 80,000 100,000
Inorga nic N fe rtil ise r (kg N ye a r -1)
kg C
O2
equ
ival
ents
l-1
mil
k
(Plassmann & Edwards-Jones submitted)
Conclusions
Conclusions
• Livestock farmers will struggle to make their current systems ‘carbon neutral’.
• Supply chain efficiency will help greatly and may create some space for ‘sustainable intensification’.
......but not much
Should we look for changes in consumption patterns?
‘How low can we go?’WWF-UK and FCRN’s views of the implications of the report
‘Perhaps the most controversial proposal to reduce GHG emissions from the food chain is to attempt to change patterns of consumption – what it is we eat.
Globally, most people do not consume nearly as much meat and dairy products as we do here in the UK.................So, it seems fair that we in the UK should consume fewer livestock products in order that those in the developing world, many of whom are undernourished, can consume a little more.
There is a growing body of scientific research that highlights the importance of cutting meat and dairy consumption both for environmental reasons, but also because of the potential health benefits to be gained.
The recent report in The Lancet (source 1) – which attracted some limited support from Government – and the Sustainable Development Commission’s ‘Setting the Table’ report (source 2) are cases in point.’
Final word
• Engage positively!• Do what you can to reduce emissions• Tell everybody what you have done.• Support renewable energy projects.
Be the best
1959 – 315 ppm 2008 – 385 ppm
Blackcap arrivals at Skokholm (source Buse et al 2001) qwsaZa|z|Z|Z|Z|Z|zZ|A|||as|Za|||zZ|Z