Organic agriculture and climate change

Abstract

This article discusses the mitigation and adaptation potential of organic agricultural systems along three main features: farming system design, cropland management and grassland and livestock management. An important potential contribution of organically managed systems to climate change mitigation is identified in the careful management of nutrients and, hence, the reduction of N 2 O emissions from soils. Another high mitigation potential of organic agriculture lies in carbon sequestration in soils. In a first estimate, the emission reduction potential by abstention from mineral fertilizers is calculated to be about 20% and the compensation potential by carbon sequestration to be about 40–72% of the world's current annual agricultural greenhouse gas (GHG) emissions, but further research is needed to consolidate these numbers. On the adaptation side, organic agriculture systems have a strong potential for building resilient food systems in the face of uncertainties, through farm diversification and building soil fertility with organic matter. Additionally, organic agriculture offers alternatives to energy-intensive production inputs such as synthetic fertilizers which are likely to be further limited for poor rural populations by rising energy prices. In developing countries, organic agricultural systems achieve equal or even higher yields, as compared to the current conventional practices, which translate into a potentially important option for food security and sustainable livelihoods for the rural poor in times of climate change. Certified organic products cater for higher income options for farmers and, therefore, can serve as promoters for climate-friendly farming practices worldwide.

Full text

Organic agriculture and climate change
Nadia El-Hage Scialabba* and Maria Mu
¨ller-Lindenlauf
Natural Resources Management and Environment Department, Food and Agriculture Organization of the
United Nations (FAO), Viale delle Terme di Caracalla, 00153 Rome, Italy.
*Corresponding author: nadia.scialabba@fao.org
Accepted 2 February 2010; First published online 30 March 2010 Review Article
Abstract
This article discusses the mitigation and adaptation potential of organic agricultural systems along three main features:
farming system design, cropland management and grassland and livestock management. An important potential contribution
of organically managed systems to climate change mitigation is identified in the careful management of nutrients and,
hence, the reduction of N
2
O emissions from soils. Another high mitigation potential of organic agriculture lies in carbon
sequestration in soils. In a first estimate, the emission reduction potential by abstention from mineral fertilizers is calculated
to be about 20% and the compensation potential by carbon sequestration to be about 40–72% of the world’s current annual
agricultural greenhouse gas (GHG) emissions, but further research is needed to consolidate these numbers. On the
adaptation side, organic agriculture systems have a strong potential for building resilient food systems in the face of
uncertainties, through farm diversification and building soil fertility with organic matter. Additionally, organic agriculture
offers alternatives to energy-intensive production inputs such as synthetic fertilizers which are likely to be further limited
for poor rural populations by rising energy prices. In developing countries, organic agricultural systems achieve equal or
even higher yields, as compared to the current conventional practices, which translate into a potentially important option for
food security and sustainable livelihoods for the rural poor in times of climate change. Certified organic products cater for
higher income options for farmers and, therefore, can serve as promoters for climate-friendly farming practices worldwide.
Key words: organic agriculture, climate change, mitigation, adaptation, carbon sequestration, diversification, resilience
Introduction
According to the Fourth Assessment Report of the
Intergovernmental Panel on Climate Change (IPCC), green-
house gas (GHG) emissions from the agricultural sector
account for 10–12% or 5.1–6.1 Gt of the total anthropo-
genic annual emissions of CO
2
-equivalents
1
. However, this
accounting includes only direct agricultural emissions;
emissions due to the production of agricultural inputs such
as nitrogen fertilizers, synthetic pesticides and fossil fuels
used for agricultural machinery and irrigation are not cal-
culated. Furthermore, land changes in carbon stocks caused
by some agricultural practices are not taken into account,
e.g., clearing of primary forests. Emissions by deforestation
due to land conversion to agriculture, which account for an
additional 12%
2
of the global GHG emissions, can be
additionally allocated to agriculture. Thus, agriculture
production practices emit at least one-quarter of global
anthropogenic GHG emissions and, if food handling and
processing activities were to be accounted for, the total
share of emissions from the agriculture and food sector
would be at least one-third of total emissions. Considering
the high contribution of agriculture to anthropogenic GHG
emissions, the choice of food production practices can be a
problem or a solution in addressing climate change.
Clearly, agriculture is highly dependent on climate
conditions and is therefore subject to change and varia-
bility, with obvious impacts on food security. Changing
environmental conditions such as rising temperatures,
changing precipitation patterns and an increase of extreme
weather events seriously affect agricultural productivity, as
vulnerability increases and even farming viability
3
. Until
2030, adverse agricultural impacts are expected mainly in
tropical areas, where agriculture provides the primary
source of livelihood for more than 60% of the population in
sub-Saharan Africa
4
and about 40–50% in Asia and the
Pacific
5
. While a temperature rise of around 2 C is already
inevitable
1
, agro-ecosystems designed to cope with stress
and adapt to change are strongly needed to facilitate food
security and sustainable livelihoods in these regions. By
2050, all agroecosystems of the world—including those in
temperate areas—are expected to be affected by climate
change
1
. Therefore, the quest for climate-proof food
systems is of interest to all.
This article discusses the mitigation and adaptation
potential of organic agricultural systems along three main
Renewable Agriculture and Food Systems: 25(2); 158–169 doi:10.1017/S1742170510000116
#Cambridge University Press 2010

features: farming system design, cropland management and
grassland and livestock management. The objective is to
draw a case where good agricultural management can com-
pensate today for most of the sector GHG emissions, while
providing food and livelihoods.
Definition of Organic Agriculture
According to the Codex Alimentarius Commission,
‘organic agriculture is a holistic production management
system that avoids use of synthetic fertilizers, pesticides and
genetically modified organisms, minimizes pollution of air,
soil and water, and optimizes the health and productivity of
interdependent communities of plants, animals and people’
6
.
To meet these objectives, organic agriculture farmers need
to implement a series of practices that optimize nutrient and
energy flows and minimize risk, such as crop rotations and
enhanced crop diversity, different combinations of live-
stock and plants, symbiotic nitrogen fixation with legumes,
application of organic manure and biological pest control.
All these strategies seek to make the best use of local
resources. Hence, organic systems are inherently adapted to
site-specific endowments and limitations
7,8
.
In this article, we refer to all agricultural systems that
implement the practices described above, and not only to
systems that are certified as organic. Organic certification is
required for market purposes, especially when distance is
great from producers to consumers and there is a need to
verify the organic claim. In developing countries, a huge
number of uncertified farms apply organic agriculture
practices for their own subsistence purposes. It is to be
highlighted that refraining from the use of synthetic inputs
does not qualify an operation as organic, as far as it is not
accompanied by a proper farm design and management that
preserves natural resources from degradation. In 2007,
certified organic lands were of 32 million hectares, in-
volving 1.2 million farmers
9
.
Farming System Design
Limited external inputs
The use of external inputs is limited in organic farming
systems. Synthetic inputs like mineral fertilizers and
chemical pesticides are banned. The energy used for the
chemical synthesis of nitrogen fertilizers, which are totally
excluded in organic systems, represent up to 0.4–0.6 Gt
CO
2
emissions
10–12
. This is as much as 10% of direct global
agricultural emissions and around 1% of total anthro-
pogenic GHG emissions. Williams et al. calculated the total
primary energy burden of conventional wheat production in
the UK to be allocated by 56% to mineral fertilizers and by
11% to pesticides
12
. Pimentel calculated similar results for
corn in USA, 30–40% for fertilization and 9–11% for plant
protection for wheat and corn
13
. These emissions are
avoided by organic agriculture.
However, where labor is not available and conditions
allow it, organic management might require more fossil
fuel energy for machinery due to the use of mechanical
weed control. A comparison of seven organic and
conventional crops carried out in the UK showed a higher
energy demand for machinery for all organic products.
However, the higher energy demand for machinery did not
outweigh the energy savings from foregoing synthetic
fertilizers and pesticides
14
. The total energy use per product
unit was lower for organic systems in all cases except for
carrots, where a high energy demand for flame weeding
was assumed. On average, the total energy demand for
organic products was 15% lower
14
.
The reduced dependency on energy inputs in organic
agriculture reduces vulnerability to rising energy prices,
and hence volatility of agricultural input prices. Nitrogen
fertilizer prices rose by 160% during the first quarter of
2008
15
, and price hikes are expected to recur with peak oil
and climate change, further limiting the access for poor
rural populations to agricultural inputs. Organic agriculture
can be a promising approach to sustain food security by
supplying alternatives to agricultural inputs.
An additional effect of the ban on nitrogen fertilizer
input is to give an incentive to enhance nutrient use
efficiency and therefore, reduce the risk of nitrous oxide
emissions. Between 1960 and 2000, while agricultural pro-
ductivity increased substantially with increased utilization
of fertilizers, the global efficiency of nitrogen use for cereal
production decreased from 80 to 30%, while the risk of
nitrogen emissions increased
16
.
Should all farming be managed organically, the current
annual production of 100 megatons of nitrogen in mineral
fertilizers and the corresponding N
2
O emissions would fall
off; using an emission factor of 1.3% for the mineral
fertilizer nitrogen, these emissions account for 10% of the
anthropogenic GHG emissions from agriculture
10,17
.
Hence, the organic ban on the use of mineral fertilizers,
reducing both energy demand for fertilizer manufacturing
and nitrous oxide emissions from fertilizer application,
could lower the direct global agricultural GHG emissions
by about 20%.
Reduced use of synthetic fertilizers is believed to result
in lower yields per land unit, depending on the level of
intensity of the previous management system. A review
by Badgley et al.
18
calculated average yield losses under
organic management for developed countries of 0–20%
and, in the case of developing countries, an increase of
yield or hardly any yield reduction. In low external input
systems, and especially in arid and semi-arid areas where
most of the food-insecure live, organic yields generally
improve up to 180%
19,20
. Higher yields in low-input
systems are mainly achieved by the application of manure
from integrated livestock production, composting and
diversification. In humid areas, where traditionally less
livestock is integrated into the farming system and hence no
livestock manure is available, organic yields depend on
the availability of other organic nitrogen sources. In paddy
rice, nitrogen is supplied by nitrogen-fixing organisms
like Azolla
21,22
, with yields comparable to conventional
Organic agriculture and climate change 159

systems
18
. In perennial cropping, such as coffee or banana,
high yield reductions are more likely, even though in some
cases higher yields were measured
18,23–27
. However, in an
appropriate agroforestry system, lower yields for the main
crop are compensated by producing other foodstuff and
goods
28,29
. Agroforestry systems are encouraged by
different standards for organic agriculture
30–32
.
Crop diversification
By abstaining from synthetic input use, organic agricultural
systems cannot but adapt to local environmental conditions.
Therefore, species and varieties are chosen for their
adaptability to the local soil and climate and their resistance
to local pests and diseases. Organic farmers prefer not to
use uniform crops and breeds and opt for more robust tra-
ditional species, which they tend to conserve and develop.
Additionally, growing different assemblages of crops in
time and space seeks to enhance the agro-ecosystem re-
silience to external shocks such as extreme weather events
or price variation
33
, which are all risks most likely to
increase as the climate changes
34
. Diverse cropping
systems in developing countries do not only rely on cash
crops but also on food crops for household consumption.
Currently, most small-scale farmers are net buyers of food
and, thus, highly vulnerable to volatile food prices
15
.An
independence from uniform commercial seeds and im-
ported food increases self-reliance and promotes food
sovereignty.
The diversification of cropping systems also make more
efficient use of available nutrients, with improved pro-
ductivity and economic performance, which is of high
importance in times of limited nutrients and financial
constraints
35
.
Integrated livesto ck production
To be successful, organic agriculture must integrate plant
and livestock production to the extent possible to optimize
nutrient use and recycling. Currently, half of the world’s pork
production originates from industrial landless systems, and
for poultry meat this share amounts to over 70%.
36
These
confined and intensive livestock systems lead to high nutrient
excess on the farm level. For the USA, a comprehensive
study carried out by the USDA in 1997 calculated a total
farm-level excess of about 60% of the recoverable manure
nitrogen and 65% of the recoverable manure phosphorus
37
.
Landless livestock production systems can rarely be
found in organic agricultural systems. According to the
EU regulations on organic production, livestock units
must not exceed 2 units per hectare, which is equivalent
to approximately 170 kg N
38
. Therefore, manure input is
tailored to plant uptake capacities, an aspect which is
recommended as a mitigation strategy by the IPCC in
order to reduce N
2
O emissions and leaching
34
. But, this
aspect of organic standards of other regions needs to be
further developed to meet the International Federation of
Organic Agricultural Movements (IFOAM) principle of a
harmonious balance between crop production and animal
husbandry.
A nutrient excess on the farm does not only lead to a high
N
2
O emission risk but also to an inefficient use of the
world’s limited resources. Where manure has to be trans-
ported over great distance for application, high energy costs
occur.
On pastures, limited livestock density avoids over-
grazing. Overgrazing is a risk factor for land degradation
and leads to high soil carbon losses
39–41
.
The limitation of livestock units per hectare and the
lower production intensity are incentives for multi-use
livestock systems. Case study calculations showed that the
methane emissions from milk and beef production can be
reduced more than 20% by keeping double-use breeds
42
(i.e., for milk and meat production). Double-use breeds are
normally not kept in conventional systems because of their
lower milk yields, but in roughage-based organic systems,
double-use breeds do not imply further yield losses and
hence are more likely to be used.
Maintenance and restoration of multi-functional
landscapes
The integration of landscape features for the establishment
of eco-functional landscapes is an important asset of
organic management. According to IFOAM, operators
shall take measures to maintain and improve landscape
and enhance biodiversity
30
. This may include extensive
field margins, hedges, trees or bushes, woodlands, water-
ways, wetlands and extensive grasslands.
The integration of landscape elements is mentioned as an
effective mitigation strategy by the IPCC
34
, due to its
multiple adaptation effects. For example, hedges and trees
are useful to reduce erosion, which is expected to be
aggravated by climate change
1
. Reduced erosion goes along
with reduced losses of soil organic matter and, hence, in-
creased soil fertility. In organic systems, the water retention
and drainage capacity of the ecosystem is enhanced and the
risk of floods or droughts is reduced. Meanwhile, carbon is
sequestered in soil and plant biomass. While in conven-
tional systems, landscape elements are cleared because they
hinder mechanization and chemical control of pests and
weeds
43
, landscape elements in organic systems are
purposely created in order to provide habitats for wildlife
that work synergistically with the cropping system; for
example, predators keep pests under check and hedges
protect from winds
44,45
.
The adaptation effects of landscape features are particu-
larly important in those areas where the strongest impacts
of climate change are expected. An analysis of climate risks
identified southern Africa and South Asia as the regions
where climate change will cause the most severe impacts
for a large food-insecure human population
46
. The organic
standards of these regions already include regulations
concerning landscape elements. According to the East
African Standard, trees shall be present and hedges should
160 N. El-Hage Scialabba and M. Mu
¨ller-Lindenlauf

be encouraged
31
. The Pacific Organic Standard contains the
most specific climate-related standards, which requests
properties over 5 ha to set aside a minimum of 5% of the
certified area for wildlife, unless the property is following a
traditional agroforestry or polyculture approach
32
.
Agroforestry systems have similar effects, even to a
higher degree. They are recommended as mitigation
strategy by the IPCC
34
and are encouraged by different
standards for organic agriculture
30–32
.
Biomass burning and deforestation
CH
4
and N
2
O from biomass burning account for 12% of the
agricultural GHG emissions. Additionally, the carbon
sequestered in the burned biomass is lost to the atmosphere.
In organic agriculture, preparation of land by burning
vegetation is restricted to a minimum
30–32
.
IFOAM organic standards ban the certification of
primary ecosystems, which have recently been cleared or
altered
31,32
. Organic agriculture thus contributes to halting
deforestation resulting from forest conversion to croplands
(12% of global GHG emissions
2
) and thus highly con-
tributes to mitigating climate change. However, further
development of organic standards is needed.
Restoration of degraded land
Organic farming practices such as crop rotation, cover
crops, manuring and application of organic amendments are
recommended strategies to restore degraded soils
47
and
hence improve the livelihoods of rural populations affected
by climate change; 70% of the land in dry areas is assumed
to be degraded
48
. In the Tigray Province, one of the most
degraded parts of Ethiopia, agricultural productivity was
doubled by soil fertility techniques over 1 million hectares
through agroforestry, application of compost and intro-
duction of leguminous plants into the crop sequence
49
.By
restoring soil fertility, yields were increased to a much
greater extent at both farm and regional levels than by using
purchased mineral fertilizers.
Restoration of degraded land not only offers income
opportunities for rural populations but also has a huge
mitigation potential by increasing soil carbon sequestration.
The total mitigation potential by restoration of degraded
land is estimated as 0.15 Gt (technical potential up to USD
20 per t of carbon) and up to 0.7 Gt (physical potential)
50
.
As degraded lands usually host market-marginalized
populations, organic land management may be the only
opportunity to improve food security through an organized
use of local labor to rehabilitate degraded land and increase
productivity and soil carbon sequestration.
Cropland Management
As nitrogen is far more limited in organic systems, there is a
strong incentive to avoid losses and enhance soil fertility
51
.
Furthermore, there is a need to reduce the risk of pest
and diseases by preventive measures. The most important
instrument for achieving these aims is a diverse crop rotation,
including catch and cover crops and intercropping.
N
2
O emissions from soils
N
2
O emissions are the most important source of agricul-
tural emissions: 38% of agricultural GHG emissions
34
. The
IPCC attributes a default value of 1% to applied fertilizer
nitrogen as direct N
2
O emissions
17
. In other publications,
emission factors of up to 3–5 kg N
2
O-N per 100 kg N-input
can be found
52
. These higher values for global N
2
O budget
are due to the consideration of both direct and indirect
emissions, including also livestock production, NH
3
and
NO
3
emissions, nitrogen leakage into rivers and coastal
zones, etc.
In organic systems, the nitrogen input to soils, and hence
the potential nitrous oxide emissions, are reduced. Mineral
fertilizers, which currently cause direct N
2
O emissions in
the range of 10% of agricultural GHG emissions, are totally
avoided (see the above section, ‘Limited external inputs’).
Catch and cover crops extract plant-available nitrogen
unused by the preceding crop and keep it in the system.
Therefore, they further reduce the level of reactive nitrogen
in the topsoil, which is the main driving factor for N
2
O
emissions
53,54
. A study from The Netherlands comparing
13 organically and conventionally managed farms showed
lower levels of soluble nitrogen in the organically managed
soils
55
.
N
2
O emissions show a very high variability over time
and are therefore difficult to determine
56
. The share of
reactive nitrogen that is emitted as N
2
O depends on a
broad range of soil and weather conditions and manage-
ment practices, which could partly foil the positive effect of
lower nitrogen levels in topsoil. Effects of different soil con-
ditions are not yet well understood. Comparisons between
soils receiving manure versus mineral fertilizers found
higher N
2
O emissions after manure application compared
to mineral fertilizer applications, but not for all soil
types
57,58
. One study from Brittany found no significant
differences between mineral and organic fertilization
59
. The
higher nitrous oxide emissions after incorporation of
manure and plant residues are explained by the high
oxygen consumption for decomposition of the organic
matter
60–62
. These peaks in N
2
O can be mitigated by
enhanced aeration of the top soil. In compacted soils, the
risk of nitrous oxide emissions is higher
63,64
. Organic man-
agement practices facilitate a lower bulk density, enhancing
soil aeration
65,66
. Low aeration is also a reason for partly
higher risk of N
2
O emissions in no-tillage systems
67
.
The highest risk for N
2
O emissions in organic farms is
the incorporation of legumes, which are the main nitrogen
source for organic farms
68
. For Germany, emissions of
9kgN
2
Oha
-1
were measured after incorporation of
legumes. But the average of N
2
O emissions over the whole
crop rotation was lower for the organic farm, as compared
to the conventional system (4 kg N
2
O per hectare for the
organic and 5 kg for the conventional system)
69
.
Organic agriculture and climate change 161

To sum up, while there are some indicators for higher
N
2
O emissions per kg nitrogen applied, there is no clear
evidence for higher emission factors in organic systems.
Regarding the lower fertilization intensity and the higher
nitrogen use efficiency in low-input systems, both leading
to lower concentrations of reactive nitrogen in top soils, a
lower overall risk of N
2
O emission from organic cultivated
soils can be assumed. However, as there is high uncertainty
in N
2
O emission factors, further research is recommended.
Carbon sequestration in cropland and
soil organic matter
A second mitigation effect of cash and cover crops,
intercropping and manure is an increased carbon sequestra-
tion in the soil
34,70,71
. Several field studies have proved the
positive effect of organic farming practice on soil carbon
pools
72–74
. In Switzerland, a long-term trial biodynamic
system showed a stable carbon content, while a carbon loss
of 15% in 21 years was measured for the compared con-
ventional system. In the USA, a field trial showed a fivefold
higher carbon sequestration in the organic system (i.e.,
1218 kg of carbon per hectare per year) in comparison
with conventional management
74,75
. The potential of
carbon sequestration rate by organic farming for European
agricultural soils has been estimated at 0–0.5 tC per hectare
per year
71
.
Niggli et al.
76
calculated the sequestration potential of
organic croplands to be 0.9–2.4 Gt CO
2
per year (which
is equivalent to an average sequestration potential of about
0.2–0.4 t C per hectare and year for all croplands), which
represents 15–47% of total annual agricultural GHG
emissions
10,34,76
.
But some practices currently discussed for their high
sequestration potential, such as no-tillage, are so far poorly
applicable in organic systems. No-tillage is difficult in
organic agricultural systems because the accompanied
insurgence of weeds cannot be faced with herbicides, as
in conventional systems, but only by mechanical weed
control, if affordable
77
. The estimated technical potential
carbon sequestration rate of conventional zero-tillage is
0.4 t C per hectare per year for Europe, which is slightly
higher than the sequestration potential of organic farming
practices. However, Freibauer et al. argued that the
realistically achievable mitigation potential for organic
agriculture is higher (i.e., 3.8 Gt as compared to less than
2.5 Gt for the European Union) due to price premium
incentives in organic management
71
. Furthermore, recent
studies question the sequestration potential of no-tillage
systems. A review carried out in 2007 found no positive
effect of no-tillage on the total soil carbon stock when
samples are taken deeper than 30 cm
78
. One study found
even higher concentrations of combustible C and N in
the topsoil of organic systems, as compared to no-till
systems
77
.
One important factor to consider in assessing soil
management impact on GHG emissions is the trade-off
between carbon sequestration and N
2
O. Conventional no-
tillage systems perform well in terms of carbon seques-
tration but can increase N
2
O emissions
79–82
. Although not
yet well analyzed, in some cases no-tillage can lead to
much higher N
2
O emissions
67
. For developing countries,
there are still few research data available concerning soil
carbon sequestration rates and N
2
O emissions.
In the long term, the removal of GHGs from the
atmosphere through soil carbon sequestration is limited.
The level of soil organic matter does not increase
indefinitely in any soil, but reaches a certain equilibrium,
depending on the soil and climatic conditions and manage-
ment practices
83
. Lal estimates the carbon sink capacity of
the world’s agricultural soils by enhanced management
practices to be 21–51 Gt carbon, which is equivalent to all
anthropogenic GHG emissions over 2–3 years, referring to
2004 emissions
84
. Thus, carbon sequestration in soils is not
sufficient to achieve a climate neutral agriculture in the
long run, but in the medium term, it can compensate
inevitable agricultural emissions until more neutral produc-
tion practices are developed and widely used.
Additionally, it must be considered that carbon seques-
tration has a mitigation effect only if the sequestration is
permanent. There are scientific results showing that the
carbon stored by no-tillage systems is released by a single
ploughing, presumably because of its labile quality
85
.
Most of the soil-sequestered carbon is stored as soil
organic matter
84
. In different long-term field trials, or-
ganic matter content in organically managed soils was
higher
86–88
. Soil organic matter has positive effects on the
water-capturing capacity of the soil. A higher water-
capturing capacity strengthens the resilience to droughts
and reduces the risk of floods
89
, which are both more likely
to increase with climate change. The need for irrigation is
lowered, which has an additional adaptation and mitigation
effect
90
. Furthermore, soil organic matter enhances the
nutrient buffer capacity and the microbial activity, both
strengthening soil fertility.
Paddy production
Another agricultural GHG source influenced by cropping
systems is methane from paddy rice fields, which accounts
for 11% of the global agricultural GHG emissions. The
main influencing factors are cultivars, organic amendments
and drainage
91
. While organic amendments increase
emissions, drainage reduces emissions
92
. Organic systems
add more organic amendments but adding amendments in
times of drainage could avoid higher emissions
93,94
.As
organic systems do not use herbicides, aquatic weeds tend
to be present in organic rice paddies—and weeds have an
additional decreasing effect on methane emissions
95
. The
yields in organic and conventional rice production do not
differ significantly
18,96,97
. Generally, there are adverse ef-
fects of organic paddy production on methane emissions
due to organic fertilization, while emission compensation
measures (such as drainage) are not mandatory. Further
162 N. El-Hage Scialabba and M. Mu
¨ller-Lindenlauf

research is needed to quantify and recommend organic
practices conducive to climate mitigation. One promising
approach could be the combination of organic practices
with resource-saving systems as the ‘system of rice
intensification’ (SRI), where soils are kept un-flooded most
of the growing period and hence methane emissions are
significantly reduced
98–100
.
Pasture, Livestock and Manure
Management
Methane emissions from enteric fermentation
One of the most important sources of GHG emissions
from agriculture are the methane emissions from enteric
fermentation, which account for 4–5% of the global
anthropogenic GHG emissions
1,34
. The quantity of methane
emitted per product unit depends on the animal diet and the
cow breed’s performance.
High milk yields per cow reduce emissions per product
unit. High energy feedstuff (e.g., grains and soya) can
reduce emissions because methane emissions mainly derive
from the digestion of fiber from roughage
101
. In developed
countries, organic management usually achieves lower milk
yields per cow than conventional production
18
; the main
reason is a more roughage-based ration with low concen-
trate supply. However in developing countries, where two-
thirds of the enteric methane emissions occur, organic
systems achieve higher milk yields, as more careful
management improves the relatively low performance of
traditional systems
102
.
In organic systems, ruminants are kept to make
productive use of fodder legumes, which play an important
role as nitrogen source in organic crop rotations. Also,
many grasslands are not suitable for cropping due to
topography, climate and soils, and the best productive use
of these lands is to keep ruminants on them. High livestock
performance is generally achieved by feeding high-energy
crops, which neglects the unique ability of ruminants to
digest roughage. Using crops for feed rather than food
poses substantial challenges to food security; currently,
one-third of the world’s cropland is used to produce animal
feed
36
, let alone all the inherent environmental problems
that intensive cropping systems pose in terms of high N-
fertilizer use, soil degradation and further land clearing.
Furthermore, high energy concentration in animal diets, if
not managed very carefully, can lead to rumen acidification
and secondary inflammations, which is a cause of animal
illness
103
. Therefore, from an organic perspective, there are
severe constrains to mitigating methane emissions from
enteric fermentation by shifting to a high-energy diet by
feeding higher amounts of concentrates. Organic principles
view livestock systems as part of a whole, including the
process through which feed is supplied. The objective of
organic livestock management, though not yet achieved, is
to create a nearly closed nutrient cycle whereby feed is
supplied on-farm. While integration and disintensification
are attempted (to different degrees) everywhere in organic
livestock systems, there is an increasing awareness of the
need to optimize the productivity of roughage with more
research and development.
Methane emissions from organic livestock systems can
be reduced by about 10% (under European conditions)
through reduced animal replacement rates
104
, as a low
replacement rate is more likely in systems with lower
performance per cow since these are not pushed beyond
their limit. Also, stress resistance (an important factor under
climate change conditions) and longevity are among the
most important traits of organic breeding
105
.
Manure management
Methane and N
2
O from manure account for about 7% of the
agricultural GHG emissions
34
. Methane emissions pre-
dominantly occur in liquid manure systems, while N
2
O
emissions are higher in solid manure systems and on
pastures
34
. There is a very high variance for both gaseous
emissions, depending on composition, coverage, tempera-
ture and moisture of the manure. Measures leading to a
reduction of methane emissions from manure often increase
emissions of N
2
O and vice versa
106
. Methane emissions
from liquid manure can be reduced nearly to zero by
fermenting the slurry in biogas plants, which would have
the positive side effect of generating renewable energy and
is in line with organic principles. For N
2
O, there is limited
mitigation potential for most animals worldwide
34
.
Carbon sequestration in grasslands
Pastures are the favored feeding strategy for organic cattle.
Therefore, organic livestock management is an option for
maintaining grasslands, which have a high carbon seques-
tration potential
34,107
. Combined with a limited livestock
density to prevent overgrazing, organic grassland farming
could be a way to optimize carbon sequestration in
grasslands
108,109
.
The global carbon sequestration potential by improved
pasture management practices was calculated to be 0.22 t C
per ha per year
110
. Assuming 0.2 t C per ha per year for
organic farming practices, the total carbon sequestration
potential of the world’s grassland would be 1.4 Gt per year
at the current state, which is equivalent to about 25% of the
annual GHG emissions from agriculture
10,34,76
.
Organic Supply Chains and Lifestyle
GHG emissions from energy use in the food chain are
normally not counted as agricultural emissions. In inven-
tory reports, they appear as emissions from energy supply,
industries and transport. There are no comprehensive data
available for the GHG emissions of the food sector on
a global scale. In the USA, 19% of the fossil energy is used
in the food sector
13
. A comparison of seven organic and
conventional crops in the UK showed a higher (n=6) or the
same (n=1) energy demand for collection, transport and
Organic agriculture and climate change 163

distribution of organic products. The disadvantage of the
organic products is due to the still small economy of scale
of organic agriculture (i.e., <2% of global food retail
9
),
leading to lower energy efficiency of collection and
distribution. This disadvantage could be compensated by
supplying products to local wholesalers and food shops
14
,
as well as by direct supply to consumers (e.g., box
schemes) and by larger economies of scale.
Additionally, organic standards tend to support low-
energy technologies for packaging. IFOAM standards
already cover packaging by advising processors of organic
food to avoid unnecessary packaging materials and to use
reusable, recycled, recyclable or biodegradable packaging,
whenever possible. This includes an intrinsic potential for
energy saving.
Certified organic agriculture is linked to consumption
patterns that seek locally adapted, healthy and ecologically
friendly foods and goods. From a consumer’s point of view,
the organic philosophy of adaptation to local conditions
involves a preference for seasonal and local food. A recent
study from Germany has shown that both seasonal and
regional consumption has remarkable effects on energy
saving
111
. For example, for apples, a threefold higher en-
ergy demand was calculated for intercontinental selling
(i.e., from New Zealand to Germany), as compared to
an average German production system that involves
6 months of cold storage (i.e., 5.1 MJ kg
-1
, as compared
to 1.6 MJ kg
-1
). Apples produced in traditional orchard
meadows showed the lowest total energy demand (i.e.,
0.6 MJ kg
-1
). Orchard meadows can be seen as an example
for agroforestry in temperate Europe and comply with the
organic aim of diversified multifunctional landscapes.
Global food trade is energy efficient only when a
production process is energy competitive as compared to
local production, either due to favorable climate (e.g.,
coffee or bananas are best produced in tropical countries) or
seasonality (e.g., vegetables). Transportation means (air,
sea or road) is another determining factor in calculating
the carbon footprint of a traded product. Regional pro-
duction does not offer advantages when heating is needed.
The Swiss organic standard already includes a strict limi-
tation for greenhouse heating and air shipping of organic
food
112
.
Despite the trend of the past decade of conventional-
ization of organic food systems, including highly processed
and functional foods, sophisticated packaging and global
retailing, organic consumers are currently reverting to less
energy demanding and decreased carbon footprint com-
modities. Currently, the organic community is developing
adequate carbon labels to be included within the organic
standards and labels
113
.
Conclusions
Organic agricultural systems have an inherent potential to
both reduce GHG emissions and to enhance carbon
sequestration in the soil (Table 1).
An important potential contribution of organically
managed systems is the careful management of nutrients,
and hence the reduction of N
2
O emissions from soils,
Table 1. Mitigation potential of organic agriculture.
Source of GHG
Share of total
anthropogenic
GHG emissions
Impacts of
optimized organic
management Remarks
Direct emissions from
agriculture
10–12%
N
2
O from soils 4.2% Reduction Higher nitrogen use efficiency
CH
4
from enteric
fermentation
3.5% Opposed effects Increased by lower performance and
lower energy concentration in the diet
but reduced by lower replacement rate
and multi-use breeds
Biomass burning 1.3% Reduction Burning avoided according to organic standards
Paddy rice 1.2% Opposed effects Increased by organic amendments but lowered
by drainage and aquatic weeds
Manure handling 0.8% Equal Reduced methane emissions but no effect
on N
2
O emissions
Direct emissions from forest
clearing for agriculture
12% Reduction Clearing of primary ecosystems restricted
Indirect emissions
Mineral fertilizers 1% Totally avoided Prohibited use of mineral fertilizers
Food chain ? (Reduction) Inherent energy saving but still inefficient
distribution systems
Carbon sequestration
Arable lands Enhanced Increased soil organic matter
Grasslands Enhanced Increased soil organic matter
164 N. El-Hage Scialabba and M. Mu
¨ller-Lindenlauf

which are the most relevant single source of direct GHG
emissions from agriculture. More research is needed to
quantify and improve the effects of organic paddy rice
production and to develop strategies to reduce methane
emissions from enteric fermentation (e.g., by promoting
double-use breeds). Indirect GHG emissions are reduced in
organic systems by avoidance of mineral fertilizers.
With the current organic consumers’ demand, further
emission reductions are expected when organic standards
include specific climate standards that consider, inter alia,
reduced energy consumption in the organic food chain
(e.g., limitations on greenhouse heating/cooling, processing
and packaging, food miles combined with life cycle
assessment). The advantage of organic systems is that they
are driven by aware consumers and that they already carry a
guarantee system of verification and labeling which is
consonant with climate labeling
113
.
The highest mitigation potential of organic agriculture
lies in carbon sequestration in soils and in reduced clearing
of primary ecosystems. The total amount of mitigation is
difficult to quantify, because it is highly dependent on
local environmental conditions and management practices.
Should all agricultural systems be managed organically,
the omission of mineral fertilizer production and appli-
cation is estimated to reduce the agricultural GHG
emissions by about 20% — 10% caused by reduced N
2
O
emissions and about 10% by lower energy demand. These
avoided emissions are supplemented by an emission
compensation potential through carbon sequestration in
croplands and grasslands of about 40–72% of the current
annual agricultural GHG emissions
76
. However, further
research is needed to confirm these figures, as long-term
scientific studies are limited and do not apply to different
kinds of soils, climates and practices. To date, most of the
research on the mitigation potential of agricultural practices
has been carried out in developed countries; dedicated
investigations are needed to assess and understand the
mitigation potential in tropical and subtropical areas and
under the predominant management practices of developing
countries.
More importantly, the adaptation aspects of organic
agricultural practices must be the focus of public policies
and research. One of the main effects of climate change is
an increase of uncertainties, both for weather events and
global food markets. Organic agriculture has a strong
potential for building resilience in the face of climate
variability (Table 2).
The total abstention from synthetic inputs in organic
agriculture has been a strong incentive to develop
agricultural management practices that optimize the natural
production potential of specific agro-ecosystems, based on
traditional knowledge and modern research. These strat-
egies can be used to enhance agricultural communities that
have no access to purchased inputs, which is the case of the
majority of the rural poor. The main organic strategies are
diversification and an increase of soil organic matter,
which both could enhance resilience against extreme
weather events and are recommended by the IPCC. These
strategies have, in particular, a high potential to enhance the
productivity of degraded soils, especially in marginal areas,
while enhancing soil carbon sequestration. The adaptive
approach inherent to organic agriculture offers simulta-
neous climate mitigation benefits.
Finally, certified organic products cater for higher
income options for producers and hence a market-based
incentive for environmental stewardship. The scaling-up of
organic agriculture would promote and support climate-
friendly farming practices worldwide. However, invest-
ments in research and development of organic agriculture
are needed to better unlock its potential and application on
a large scale.
Acknowledgements. We thank Darko Znaor and Peter Melchett
for their helpful comments.
Table 2. Adaptation potential of organic agriculture.
Objectives Means Impacts
Alternative to industrial production
inputs (i.e., mineral fertilizers
and agrochemicals) to decrease
pollution
Improvement of natural resources
processes and environmental
services (e.g., soil formation,
predation)
Reliance on local resources and independence
from volatile prices of agricultural inputs
(e.g., mineral fertilizers) that accompany
fossil fuel hikes
In situ conservation and development
of agrobiodiversity
Farm diversification (e.g., polycropping,
agroforestry and integrated
crop/livestock) and use of local
varieties and breeds
Risk splitting (e.g., pests and diseases),
enhanced use of nutrient and energy
flows, resilience to climate variability and
savings on capital-intensive seeds and breeds
Landscaping Creation of micro-habitats (e.g., hedges),
permanent vegetative cover and
wildlife corridors
Enhanced ecosystem balance (e.g., pest
prevention), protection of wild biodiversity
and better resistance to wind and heat waves
Soil fertility Nutrient management (e.g., rotations,
coralling, cover crops and
manuring)
Increased yields, enhanced soil water
retention/drainage (better response to
droughts and floods), decreased irrigation
needs and avoided land degradation
Organic agriculture and climate change 165

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