Mitigating Climate Change through Organic Agriculture and Localized Food Systems

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Mitigating Climate Change through Organic Agriculture and Localized Food Systems

 

 

Organic, sustainable agriculture that localize food systems has the potential to

mitigate nearly thirty percent of global greenhouse gas emissions and save

one-sixth of global energy use. Dr. Mae-Wan Ho and Lim Li Ching

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Modern industrial agriculture of the 1CGreen Revolution 1D contributes a great

deal to climate change. It is the main source of the potent greenhouse gases

nitrous oxide and methane; it is heavily dependent on the use of fossil fuels,

and contributes to the loss of soil carbon to the atmosphere [1] (Feeding the

World under Climate Change, SiS 24), especially through deforestation to make

more land available for crops and plantations. Deforestation is predicted to

accelerate as bio-energy crops are competing for land with food crops [2]

(Biofuels: Biodevastation, Hunger & False Carbon Credits, SiS 33). But what

makes our food system really unsustainable is the predominance of the globalised

commodity trade that has resulted in the integration of the food supply chain

and its concentration in the hands of a few transnational corporations. This

greatly increases the carbon footprint and energy intensity of our food

consumption, and at tremendous social and other environmental costs. A UK

government report on food miles estimated the direct social, environmental, and

economic costs of food transport at over £9 billion each year, which is 34

percent of the £26.2 billion food and drinks market in the UK [3] (Food Miles

and Sustainability, SiS 28).

Consequently, there is much scope for mitigating climate change and reversing

the damages through making agriculture and the food system as a whole

sustainable, and this is corroborated by substantial scientific and empirical

evidence (see below). It is therefore rather astonishing that the

Intergovernmental Panel on Climate Change should fail to mention organic

agriculture as a means of mitigating climate change in its latest 2007 report

[4]; nor does it mention localising food systems and reducing long distance food

transport [5].

 

Reducing direct and indirect energy use in agriculture

 

There is no doubt that organic, sustainable agricultural practices can provide

synergistic benefits that include mitigating climate change. As stated in the

2002 report of the United Nations Food and Agriculture Organisation (FAO),

organic agriculture enables ecosystems to better adjust to the effects of

climate change and has major potential for reducing agricultural greenhouse gas

emissions [6].

The FAO report found that, 1COrganic agriculture performs better than

conventional agriculture on a per hectare scale, both with respect to direct

energy consumption (fuel and oil) and indirect consumption (synthetic

fertilizers and pesticides) 1D, with high efficiency of energy use.

Since 1999, the Rodale Institute 19s long-term trials in the United States have

reported that energy use in the conventional system was 200 percent higher than

in either of two organic systems - one with animal manure and green manure, the

other with green manure only - with very little differences in yields [7].

Research in Finland showed that while organic farming used more machine hours

than conventional farming, total energy consumption was still lowest in organic

systems [8]; that was because in conventional systems, more than half of total

energy consumed in rye production was spent on the manufacture of pesticides.

Organic agriculture was more energy efficient than conventional agriculture in

apple production systems [9, 10]. Studies in Denmark compared organic and

conventional farming for milk and barley grain production [11]. The energy used

per kilogram of milk produced was lower in the organic than in the conventional

dairy farm, and it also took 35 percent less energy to grow a hectare of organic

spring barley than conventional spring barley. However, organic yield was lower,

so energy used per kg barley was only marginally less for the organic than for

the conventional.

The total energy used in agriculture accounts for about 2.7 percent of UK 19s

national energy use [12], and about 1.8 percent of national greenhouse gas

emissions [13] based on figures for 2002, the latest year for which estimates

are available. Most of the energy input (76.2 percent) is indirect, and comes

from the energy spent to manufacture and transport fertilizers, pesticides, farm

machinery, animal feed and drugs. The remaining 23.8 percent is used directly on

the farm for driving tractors and combine harvesters, crop drying, heating and

lighting glasshouses, heating and ventilating factory farms for pigs and

chickens. Nitrogen fertiliser is the single most energy intensive input,

accounting for 53.7 percent of the total energy use. Thus, phasing out nitrogen

fertilizer will save 1.5 percent of national energy use and one percent of

national ghg emissions, not counting the nitrous oxide from N fertilizers

applied to the fields (see below). Globally, the savings in fossil energy use

and ghg emissions could easily be double these figures.

It takes 35.3 MJ of energy on average to produce each kg of N in fertilizers

[14]. UK farmers use about 1 million tonnes of N fertilisers each year. Organic

farming is more energy efficient mainly because it does not use chemical

fertilizers [15].

The Soil Association found that organic farming in the UK is overall about 26

percent more efficient in energy use per tonne of produce than conventional

farming, excluding tomatoes grown in heated greenhouses [15]. The savings differ

for different crops and sectors, being the greatest in the milk and beef, which

use respectively 28 and 41 percent less energy than their conventional

counterparts.

Amid rapidly rising oil prices in 2006, with farmers across the country deeply

worried over the consequent increase in their production costs, David Pimentel

at Cornell University, New York, in the United States returned to his favourite

theme [16]: organic agriculture can reduce farmers 19 dependence on energy and

increase the efficiency of energy use per unit of production, basing his

analysis on new data.

On farms throughout the developed world, considerable fossil energy is invested

in agricultural production. On average in the US, about 2 units of fossil fuel

energy is invested to harvest a unit of energy in crop. That means the US uses

more than twice the amount of fossil energy than the solar energy captured by

all the plants, which is ultimately why its agriculture cannot possibly sustain

anything like the biofuel production promoted by George W. Bush [17] (Biofuels

for Oil Addicts, SiS 30).

Corn is a high-yield crop and delivers more kilocalories of energy in the

harvested grain per kilocalorie of fossil energy invested than any other major

crop [16]. `

Counting all energy inputs in fossil fuel equivalents in an organic corn system,

the output over input ratio was 5.79 (i.e., you get 5.79 units of corn energy

for every unit of energy you spent), compared to 3.99 in the conventional

system. The organic system collected 180 percent more solar energy than the

conventional. There was also a total energy input reduction of 31 percent, or 64

gallons fossil fuel saving per hectare. If 10 percent of all US corn were grown

organically, the nation would save approximately 200 million gallons of oil

equivalents.

Organic soybean yielded 3.84 kilocalories of food energy per kilo of fossil

energy invested, compared to 3.19 in the conventional system and the energy

input was 17 percent lower. Organic beef grass-fed system required 50 percent

less fossil fuel energy than conventional grain-fed beef.

 

Lower greenhouse gas emissions

 

Globally, agriculture is estimated to contribute directly 11 percent to total

greenhouse gas emissions (2005 figures from Intergovernmental Panel on Climate

Change) [18]. The total emissions were 6.1Gt CO2e, made up almost entirely of

CH4 (3.3 Gt ) and N2O (2.8Gt). The contributions will differ from one country to

another, especially between countries in the industrial North compared with

countries whose economies are predominantly agricultural.

In the United States, agriculture contributes 7.4 percent of the national

greenhouse gas emissions [19]. Livestock enteric fermentation and manure

management account for 21 percent and 8 percent respectively of the national

methane emissions. Agricultural soil management, such as fertilizer application

and other cropping practices, accounts for 78 percent of the nitrous oxide

emitted.

In the UK, agriculture is estimated to contribute directly 7.4 percent to the

nation 19s greenhouse gas emissions, with fertilizer manufacture contributing a

further 1 percent [20], and is comprised entirely of methane at 37.5 percent of

national total [21] and nitrous oxide at around 95 percent of the national total

[22]. Enteric fermentation is responsible for 86 percent of the methane

contribution from agriculture, the rest from manure; while nitrous oxide

emissions are dominated by synthetic fertilizer application (28 percent) and

leaching of fertilizer nitrogen and applied animal manures to ground and surface

water (27 percent) [23].

Assuming half of all nitrous oxide emissions come from N fertilizers, phasing

them out would save 11.56 Mt of CO2e. This is equivalent to another 1.5 percent

of the national ghg emissions. The total ghg savings from phasing out N

fertilizers amount to 2.5 percent of UK 19s national emissions. The UK is not a

prolific user of N fertilizers compared to other countries, so globally, it

seems reasonable to estimate that phasing out N fertilizers could save at least

5 percent of the world 19s ghg emissions. This is consistent with earlier

predictions.

The FAO had already estimated that organic agriculture is likely to emit less

nitrous oxide (N2O) [6]. This is due to lower N inputs, less N from organic

manure from lower livestock densities; higher C/N ratios of applied organic

manure giving less readily available mineral N in the soil as a source of

denitrification; and efficient uptake of mobile N in soils by using cover crops.

Greenhouse gas emissions were calculated to be 48-66 percent lower per hectare

in organic farming systems in Europe [24], and were attributed to no input of

chemical N fertilizers, less use of high energy consuming feedstuffs, low input

of P, K mineral fertilizers, and elimination of pesticides, as characteristic of

organic agriculture.

Many experiments have found reduced leaching of nitrates from organic soils into

ground and surface waters, which are a major source of nitrous oxide (see

above). A study reported in 2006 also found reduced emissions of nitrous oxide

from soils after fertilizer application in the fall, and more active

denitrifying in organic soils, which turns nitrates into benign N2 instead of

nitrous oxide and other nitrogen oxides [25] (see Cleaner Healthier Environment

for All, SiS 37).

It is also possible that moving away from a grain-fed to a predominantly

grass-fed organic diet may reduce the level of methane generated, although this

has yet to be empirically tested. Mike Abberton, a scientist at the Institute of

Grassland and Environmental Research in Aberystwyth, has pointed to rye grass

bred to have high sugar levels, white clover and birdsfoot trefoil as

alternative diets for livestock that could reduce the quantity of methane

produced [26].

A study in New Zealand had suggested that methane output of sheep on the changed

diet could be 50 percent lower. The small UK study did not achieve this level of

reduction, but found nevertheless that 1Csignificant quantities 1D of methane

could be prevented from getting into the atmosphere. Growing clover and birdfoot

trefoil could help naturally fix nitrogen in organic soil as well as reduce

livestock methane.

 

Greater carbon sequestration

 

Soils are an important sink for atmospheric CO2, but this sink has been

increasingly depleted by conventional agricultural land use, and especially by

turning tropical forests into agricultural land. The Stern Review on the

Economics of Climate Change commissioned by the UK Treasury and published in

2007 [27] highlights the fact that 18 percent of the global greenhouse gas

emissions (2000 estimate) comes from deforestation, and that putting a stop to

deforestation is by far the most cost-effective way to mitigate climate change,

for as little as $1/ t CO2 [28] (see The Economics of Climate Change, SiS 33).

There is also much scope for converting existing plantations to sustainable

agroforestry and to encourage the best harvesting practices and multiple uses of

forest plantations [29, 30] (Multiple Uses of Forests, Sustainable

Multi-cultures for Asia & Europe, SiS 26)

Sustainable agriculture helps to counteract climate change by restoring soil

organic matter content as well as reducing soil erosion and improving soil

physical structure. Organic soils also have better water-holding capacity, which

explains why organic production is much more resistant to climate extremes such

as droughts and floods [31] (Organic Agriculture Enters Mainstream, Organic

Yields on Par with Conventional & Ahead during Drought Years, SiS 28), and water

conservation and management through agriculture will be an increasingly

important part of mitigating climate change.

The evidence for increased carbon sequestration in organic soils seems clear.

Organic matter is restored through the addition of manures, compost, mulches and

cover crops.

The Sustainable Agriculture Farming Systems (SAFS) Project at University of

California Davis in the United States [32] found that organic carbon content of

the soil increased in both organic and low-input systems compared with

conventional systems, with larger pools of stored nutrients. Similarly, a study

of 20 commercial farms in California found that organic fields had 28 percent

more organic carbon [33]. This was also true in the Rodale Institute trials,

where soil carbon levels had increased in the two organic systems after 15

years, but not in the conventional system [34]. After 22 years, the organic

farming systems averaged 30 percent higher in organic matter in the soil than

the conventional systems [31].

In the longest running agricultural trials on record of more than 160 years, the

Broadbalk experiment at Rothamsted Experimental Station, manure-fertilized

farming systems were compared with chemical-fertilized farming systems [35]. The

manure fertilized systems of oat and forage maize consistently out yielded all

the chemically fertilized systems. Soil organic carbon showed an impressive

increase from a baseline of just over 0.1 percent N (a marker for organic

carbon) at the start of the experiment in 1843 to more than double at 0.28

percent in 2000; whereas those in the unfertilized or chemical-fertilized plots

had hardly changed in the same period. There was also more than double the

microbial biomass in the manure-fertilized soil compared with the

chemical-fertilized soils.

It is estimated that up to 4 tonnes CO2 could be sequestered per hectare of

organic soils each year [36]. On this basis, a fully organic UK could save 68 Mt

of CO2 or 10.35 percent of its ghg emissions each year. Similarly, if the United

States were to convert all its 65 million hectares of crop lands to organic, it

would save 260 Mt CO2 a year [37]. Globally, with 1.5335 billion hectares of

crop land [38] fully organic, an estimated 6.134 Gt of CO2 could be sequestered

each year, equivalent to more than 11 percent of the global emissions, or the

entire share due to agriculture.

As Pimentel stated [16]: 1C..high level of soil organic matter in organic

systems is directly related to the high energy efficiencies observed in organic

farming systems; organic matter improves water infiltration and thus reduces

soil erosion from surface runoff, and it also diversifies soil-food webs and

helps cycle more nitrogen from biological sources within the soil. 1D

Reducing energy and greenhouse gas emissions in localised sustainable food

systems

Agriculture accounts only for a small fraction of the energy consumption and

greenhouse gas emissions of the entire food system.

Pimentel [16] estimated that the US food system uses about 19 percent of the

nation 19s total fossil fuel energy, 7 percent for farm production, 7 percent

for processing and packaging and 5 percent for distribution and preparation.

This is already an underestimate, as it does not include energy embodied in

buildings and infrastructure, energy in food wasted, nor in treating food wastes

and processing and packaging waste, which would be necessary in a full life

cycle accounting.

Similarly, when the emissions from the transport, distribution, storage, and

processing of food are added on, the UK food system is responsible for at least

18.4 percent of the national greenhouse gas emissions [39], again, not counting

buildings and infrastructure involved in food distribution, nor wastes and waste

treatments.

Here 19s an estimate of the greenhouse gas emissions from eating based on a full

life cycle accounting, from farm to plate to waste, from data supplied by CITEPA

(Centre Interprofessionnel Technique d 19Eudes de la Pollution Atmosphérique)

for France [37].

 

Greenhouse gas emissions from eating (France)

 

______

Agriculture direct emissions 42.0 Mt C

Fertilizers (French fertilizer industry only, more than half imported.) 0.8 Mt C

Road transport goods (within France only, not counting export/import) 4.0 Mt C

Road transport people 1.0 Mt C

Truck manufacture & diesel 0.8 Mt C

Store heating (20% national total) 0.4 Mt C

Electricity (nuclear energy in France, multiply by 5 elsewhere) 0.7 Mt C

Packaging 1.5 Mt C

End of life of packaging (overall emissions of waste 4 Mt) 1.0 Mt C

Total 52.0 Mt C

National French emission 171.0 MtC

Share linked to food system 30.4%

 

 

The figure of 30.4 percent is still an underestimate, because it leaves out

emissions from the fertilizers imported, from pesticides, and transport

associated with import/export of food. Also, the emission of electricity from

established nuclear power stations in France is one-fifth of typical non-nuclear

sources. Others may argue that one needs to include infrastructure costs, so

that buildings and roads, as well as the building of nuclear power stations need

to be accounted for.

On the most conservative estimates based on these examples, localising food

systems could save at least 10 percent of CO2 emissions and 10 percent of energy

use globally.

The tale of a bottle of ketchup

It is estimated that food manufacturing is responsible for 2.2 percent and

packaging for 0.9 percent of UK 19s ghg emissions [20], while in the US, 7

percent of the nation 19s energy use goes into food processing and packaging.

A hint of how food processing and packaging contribute to the energy and

greenhouse gas budgets of the food system can be gleaned by the life-cycle

analysis of a typical bottle of ketchup.

The Swedish Institute for Food and Biotechnology did a life-cycle analysis of

tomato ketchup, to work out the energy efficiency and impacts, including the

environmental effects of global warming, ozone depletion, acidification,

eutrophication, photo-oxidant formation, human toxicity and ecotoxicity [41].

The product studied is one of the most common brands of tomato ketchup sold in

Sweden, marketed in 1 kg red plastic bottles. Tomato is cultivated and processed

into tomato paste in Italy, packaged and transported to Sweden with other

ingredients to make tomato ketchup.

The aseptic bags used to package the tomato paste were produced in the

Netherlands and transported to Italy; the bagged tomato paste was placed in

steel barrels, and moved to Sweden. The five-layered red bottles were either

made in the UK or Sweden with materials from Japan, Italy, Belgium, the USA and

Denmark. The polypropylene screw cap of the bottle and plug were produced in

Denmark and transported to Sweden. Additional low-density polyethylene

shrink-film and corrugated cardboard were used to distribute the final product.

Other ingredients such as sugar, vinegar, spices and salt were also imported.

The bottled product was then shipped through the wholesale retail chain to

shops, and bought by households, where it is stored refrigerated from one month

to a year. The disposal of waste package, and the treatment of wastewater for

the production of ketchup and sugar solution (from beet sugar) were also

included in the accounting.

The accounting of the whole system was split up into six subsystems:

agriculture, processing, packaging, transport, shopping and household.

There are still many things left out, so the accounting is nowhere near

complete: the production of capital goods (machinery and building), the

production of citric acid, the wholesale dealer, transport from wholesaler to

the retailer, and the retailer. Likewise, for the plastic bottle, ingredients

such as adhesive, ethylenevinylalcohol, pigment, labels, glue and ink were

omitted. For the household, leakage of refrigerants was left out. In

agriculture, the assimilation of carbon dioxide by the crops was not taken into

consideration, neither was leakage of nutrients and gas emissions such as

ammonia and nitrous oxide from the fields. No account was taken of pesticides.

We estimated the energy use and carbon emissions for each of the six subsystems

from the diagrams provided in the research paper, and have taken the energy

content of tomato ketchup from another brand to present their data in another

way (Tables 1 and 2), taking the minimum values of energy and emissions costs.

 

Table 1. Energy Accounting for 1 kg Tomato Ketchup

______

Subsystem Energy GJ

______

Agriculture 1.3

Processing 7.2

Packaging 7.8 (without waste incineration)

6.0 (with waste incineration)

Transport 1.0

Shopping 1.2

Household 1.4 (refrigeration for one month)

14.8 (refrigeration for one year)

Total (minimum) 18.1

Energy in 1 kg tomato paste 0.00432

Energy use per GJ tomato paste 4 190

 

Table 2. Carbon Dioxide Accounting for 1 kg Tomato Ketchup

______

Subsystem Carbon dioxide equivalent kg

______

Agriculture 190

Processing 500

Packaging 1 275 (without incineration)

2 315 (with incineration)

Transport 130

Shopping 195

Household 0

Total (minimum) 2 290

 

As can be seen, it takes at least 4190 units of energy to deliver 1 unit of

ketchup energy to our dinner table, with at least 2 290 kg of carbon dioxide

emissions per kg ketchup.

Packaging and food processing were the hotspots for many impacts. But at least

part of the packaging is due to the necessity for long distance transport.

Within the household, the length of time stored in the refrigerator was

critical.

For eutrophication, the agricultural system is an obvious hotspot. For nitrous

oxide emissions, transportation is another hotspot. For toxicity, the

agriculture, food processing and packaging were hotspots, due to emissions of

sulphur dioxide, nitrogen oxides and carbon monoxide; also heavy metals, phenol

or crude oil. If leakage of pesticides, their intermediates and breakdown

products had been considered, then agriculture would have been an even worse

toxicological hotspot.

As regards the capital costs for tomato cultivation omitted from the study,

literature from France gave a value of 0.180GJ/kg. As regards the wholesale and

retail step left out of the study, literature data indicate 0.00143GJ/kg beer

for storage at wholesale trader in Switzerland and 0.00166GJ/kg bread in the

Netherlands.

There is clearly a lot of scope in reducing transport, processing and packaging,

as well as storage in our food system, all of which argue strongly in favour of

food production for local consumption in addition to adopting organic,

sustainable agricultural practices. An integrated organic food and energy farm

that turns wastes into resources can be the ideal solution to reducing

greenhouse gas emissions at source, decreasing environmental pollution, reducing

transport, and increasing energy efficiencies to the point of not having to use

fossil fuels altogether [42] (Dream Farm 2, Organic, Sustainable, Fossil Fuel

Free, In Food Futures Now, ISIS Publication).

Assuming that it is feasible to reduce the energy consumption and carbon

emissions by 50 percent, at least partly due to localising food systems, this

could save 3.5 percent of global energy use and 1.5 percent of global ghg

emissions.

Total mitigating potential of organic sustainable food systems

The preliminary estimates of the potential of organic sustainable food systems

to mitigate climate change based on work reviewed in this Chapter are presented

in Box 2.

Box 2 Global potential of organic sustainable food systems for mitigating

climate change

Greenhouse gas emissions

 

Carbon sequestration in organic soil 11.0 %

Localising food systems

Reduced transport 10.0%

Reduced processing & packaging 1.5 %

Phasing out N fertilizers

Reduced nitrous oxide emissions 5.0 %

No fossil fuels used in manufacture 2.0 %

Total 29.5 %

Energy

Localising food system

Reduced transport 10.0 %

Reduced processing & packaging 3.5 %

Phasing out N fertilizers

No fossil fuels used 3.0 %

Total 16.5 %

 

The total mitigating potential of organic sustainable food systems is 29.5

percent of global ghg emissions and 16.5 percent of energy use, the largest

components coming from carbon sequestration and reduced transport from

relocalising food systems.