Understanding carbon footprints in order to meet the challenge of sustainable intensification Gareth...

Understanding carbon footprints in order to meet the challenge of

sustainable intensification

Gareth Edwards-Jones

Bangor University U.K.

Contact: g.ejones@bangor.ac.uk

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

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