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COMMENTARY: Ruminants, climate change and climate policy

Authors:

Abstract

Greenhouse gas emissions from ruminant meat production are significant. Reductions in global ruminant numbers could make a substantial contribution to climate change mitigation goals and yield important social and environmental co-benefits. A lthough a main focus of climate policy has been to reduce fossil fuel consumption, large cuts in CO 2 emissions alone will not abate climate change. At present non-CO 2 greenhouse gases contribute about a third of total anthropogenic CO 2 equivalent (CO 2 e) emissions and 35–45% of climate forcing (the change in radiant energy retained by Earth owing to emissions of long-lived greenhouse gases) resulting from those emissions 1 (Fig.1a). Only with large simultaneous reductions in CO 2 and non-CO 2 emissions will direct radiative forcing be reduced during this century (Fig.1b). Methane (CH 4) is the most abundant non-CO 2 greenhouse gas and because it has a much shorter atmospheric lifetime (~9years) than CO 2 it holds the potential for more rapid reductions in radiative forcing than would be possible by controlling emissions of CO 2 alone. There are several important anthropogenic sources of CH 4 : ruminants, the fossil fuel industry, landfills, biomass burning and rice production (Fig.1c). We focus on ruminants for four reasons. First, ruminant production is the largest source of anthropogenic CH 4 emissions (Fig.1c) and globally occupies more area than any other land use. Second, the relative neglect of this greenhouse gas source suggests that awareness of its importance is inappropriately low. Third, reductions in ruminant numbers and ruminant meat production would simultaneously benefit global food security, human health and environmental conservation. Finally, with political will, decreases in worldwide ruminant populations could potentially be accomplished quickly and relatively inexpensively. Ruminant animals consist of both native and domesticated herbivores that consume plants and digest them through the process of enteric fermentation in a multichambered stomach. Methane is produced as a by-product of microbial digestive processes in the rumen. Non-ruminants or 'monogastric' animals such as pigs and poultry have a single-chambered stomach to digest food, and their methane emissions are negligible in comparison. There are no available estimates of the number of wild ruminants, but it is likely that domestic ruminants greatly outnumber the wild population, with a reported 3.6billion domestic ruminants on Earth in 2011 (1.4 billon cattle, 1.1 billion sheep, 0.9 billion goats and 0.2 billon buffalo) 2 . On average, 25million domestic ruminants have been added to the planet each year (2million per month) 2 over the past 50years (Fig.1d). Worldwide, the livestock sector is responsible for approximately 14.5% of all anthropogenic greenhouse gas emissions 3 (7.1of 49GtCO 2 eyr –1). Approximately 44% (3.1GtCO 2 eyr –1) of the livestock sector's emissions are in the form of CH 4 from enteric fermentation, manure and rice feed, with the remaining portions almost equally shared between CO 2 (27%, 2GtCO 2 eyr –1) from land-use change and fossil fuel use, and nitrous oxide (N 2 O) (29%, 2GtCO 2 eyr –1) from fertilizer applied to feed-crop fields and manure 3 . Ruminants contribute significantly more (5.7GtCO 2 eyr –1) to greenhouse gas emissions than monogastric livestock (1.4GtCO 2 eyr –1), and emissions due to cattle (4.6GtCO 2 eyr –1) are substantially higher than those from buffalo (0.6GtCO 2 eyr –1) or sheep and goats (0.5GtCO 2 eyr –1) 3 . Globally, ruminants contribute 11.6% and cattle 9.4% of all greenhouse gas emissions from anthropogenic sources. The total area dedicated to grazing encompasses 26% of the terrestrial surface of the planet 4 . Livestock production accounts for 70% of global agricultural land and the area dedicated to feed-crop production represents 33% of total arable land 4 . The feeding of crops to livestock is in direct competition with producing crops for human consumption (food security) and climate mitigation (bioenergy production or carbon sequestration) 5 . Deforestation has been responsible for a significant proportion of global greenhouse gas emissions from the livestock sector and takes place mostly in tropical areas, where expansion of pasture and arable land for animal feed crops occurs primarily at the expense of native forests 4,6 . Lower demand for ruminant meat would therefore reduce a significant driver of tropical deforestation and associated burning and black carbon emissions. The accompanying reduction in grazing intensity could also allow regrowth of forests and other natural vegetation, resulting in additional carbon sequestration in both biomass and soils with beneficial climate feedbacks 5,6 . Lower global ruminant numbers would have simultaneous benefits for other systems and processes. For example, in some grassland and savannah ecosystems, domestic ruminant grazing contributes to land degradation through desertification and reduced soil organic carbon 5 . Ruminant agriculture can also have negative impacts on water quality and availability, hydrology and riparian ecosystems 4,7 . Ruminant production can erode biodiversity through a wide range of processes such as forest loss and degradation, land-use intensification, exotic plant invasions, soil erosion, persecution of large predators and competition with wildlife for resources 4–7 . Ruminant production also has implications for food security and human
2 NATURE CLIMATE CHANGE | VOL 4 | JANUARY 2014 | www.nature.com/natureclimatechange
opinion & comment
COMMENTARY:
Ruminants, climate change and
climate policy
William J. Ripple, Pete Smith, Helmut Haberl, Stephen A. Montzka, Clive McAlpine and Douglas H. Boucher
Greenhouse gas emissions from ruminant meat production are significant. Reductions in global ruminant
numbers could make a substantial contribution to climate change mitigation goals and yield important
social and environmental co-benefits.
Although a main focus of climate
policy has been to reduce fossil fuel
consumption, large cuts in CO2
emissions alone will not abate climate
change. At present non-CO2 greenhouse
gases contribute about a third of total
anthropogenic CO2 equivalent (CO2e)
emissions and 35–45% of climate forcing
(the change in radiant energy retained by
Earth owing to emissions of long-lived
greenhouse gases) resulting from those
emissions1 (Fig.1a). Only with large
simultaneous reductions in CO2 and
non-CO2 emissions will direct radiative
forcing be reduced during this century
(Fig.1b). Methane (CH4) is the most
abundant non-CO2 greenhouse gas and
because it has a much shorter atmospheric
lifetime (~9years) than CO2 it holds the
potential for more rapid reductions in
radiative forcing than would be possible by
controlling emissions of CO2 alone.
ere are several important anthropogenic
sources of CH4: ruminants, the fossil
fuel industry, landlls, biomass burning
and rice production (Fig.1c). We focus
on ruminants for four reasons. First,
ruminant production is the largest source
of anthropogenic CH4 emissions (Fig.1c)
and globally occupies more area than any
other land use. Second, the relative neglect
of this greenhouse gas source suggests that
awareness of its importance is inappropriately
low. ird, reductions in ruminant
numbers and ruminant meat production
would simultaneously benet global food
security, human health and environmental
conservation. Finally, with political will,
decreases in worldwide ruminant populations
could potentially be accomplished quickly
and relatively inexpensively.
Ruminant animals consist of both
native and domesticated herbivores that
consume plants and digest them through
the process of enteric fermentation in a
multichambered stomach. Methane is
produced as a by-product of microbial
digestive processes in the rumen.
Non-ruminants or ‘monogastric’
animals such as pigs and poultry have a
single-chambered stomach to digest food,
and their methane emissions are negligible
in comparison. ere are no available
estimates of the number of wild ruminants,
but it is likely that domestic ruminants
greatly outnumber the wild population,
with a reported 3.6billion domestic
ruminants on Earth in 2011 (1.4 billon
cattle, 1.1 billion sheep, 0.9 billion goats and
0.2 billon bualo)2. On average, 25million
domestic ruminants have been added to the
planet each year (2million per month)2 over
the past 50years (Fig.1d).
Worldwide, the livestock sector is
responsible for approximately 14.5% of all
anthropogenic greenhouse gas emissions3
(7.1of 49GtCO2eyr–1). Approximately
44% (3.1GtCO2eyr–1) of the livestock
sector’s emissions are in the form of CH4
from enteric fermentation, manure and
rice feed, with the remaining portions
almost equally shared between CO2 (27%,
2GtCO2eyr–1) from land-use change and
fossil fuel use, and nitrous oxide (N2O)
(29%, 2GtCO2eyr–1) from fertilizer
applied to feed-crop elds and manure3.
Ruminants contribute signicantly more
(5.7GtCO2eyr–1) to greenhouse gas
emissions than monogastric livestock
(1.4GtCO2eyr–1), and emissions
due to cattle (4.6GtCO2eyr–1) are
substantially higher than those from
bualo (0.6GtCO2eyr–1) or sheep
and goats (0.5GtCO2eyr–1)3. Globally,
ruminants contribute 11.6% and cattle
9.4% of all greenhouse gas emissions
from anthropogenic sources. e total
area dedicated to grazing encompasses
26% of the terrestrial surface of the
planet4. Livestock production accounts for
70% of global agricultural land and the
area dedicated to feed-crop production
represents 33% of total arable land4. e
feeding of crops to livestock is in direct
competition with producing crops for
human consumption (food security) and
climate mitigation (bioenergy production or
carbon sequestration)5.
Deforestation has been responsible for a
signicant proportion of global greenhouse
gas emissions from the livestock sector and
takes place mostly in tropical areas, where
expansion of pasture and arable land for
animal feed crops occurs primarily at the
expense of native forests4,6. Lower demand
for ruminant meat would therefore reduce
a signicant driver of tropical deforestation
and associated burning and black carbon
emissions. e accompanying reduction in
grazing intensity could also allow regrowth
of forests and other natural vegetation,
resulting in additional carbon sequestration
in both biomass and soils with benecial
climate feedbacks5,6.
Lower global ruminant numbers would
have simultaneous benets for other
systems and processes. For example, in
some grassland and savannah ecosystems,
domestic ruminant grazing contributes to
land degradation through desertication
and reduced soil organic carbon5. Ruminant
agriculture can also have negative impacts
on water quality and availability, hydrology
and riparian ecosystems4,7. Ruminant
production can erode biodiversity
through a wide range of processes such
as forest loss and degradation, land-use
intensication, exotic plant invasions, soil
erosion, persecution of large predators and
competition with wildlife for resources4–7.
Ruminant production also has
implications for food security and human
© 2014 Macmillan Publishers Limited. All rights reserved
NATURE CLIMATE CHANGE | VOL 4 | JANUARY 2014 | www.nature.com/natureclimatechange 3
opinion & comment
health. Roughly one in eight people in the
world are severely malnourished or lack
access to food owing to poverty and high
food prices2. With over 800 million people
chronically hungry, we argue that the use
of highly productive croplands to produce
animal feed is questionable on moral grounds
because this contributes to exhausting the
world’s food supply. Conversely, ruminant
agriculture will remain important in pastoral
or subsistence situations where ruminants
can provide a source of food from landscapes
that cannot be used to practicably sustain
crops (for example, grasslands). For these
regions, particularly in developing countries,
ruminants represent a stock that can buer
against times of bad harvest or other
detrimental uctuations.
In developed countries, high levels
of meat consumption rates are strongly
correlated with rates of diseases such as
obesity, diabetes, some common cancers and
heart disease8,9. Moreover, reducing meat
consumption and increasing the proportion
of dietary protein obtained from high-
protein plant foods — such as soy, pulses,
cereals and tubers — is associated with
signicant human health benets8,9.
Although policymakers strive to reduce
fossil fuel emissions, the livestock sector has
generally been exempt from climate policies
and little is being done to alter patterns of
production and consumption of ruminant
meat products5,10. Annual meat production
worldwide is growing rapidly, and without
policy changes is projected to more than
double from 229milliontonnes in 2000 to
465milliontonnes in 20504. e greenhouse
gas footprint of consuming ruminant
meat is, on average, 19–48 times higher
than that of high-protein foods obtained
from plants (Fig.2), when full life cycle
analysis including both direct and indirect
environmental eects from ‘farm to fork’ for
enteric fermentation, manure, feed, fertilizer,
processing, transportation and land-use
change are considered. Non-ruminant
meats such as those from pigs and poultry
(and marine sheries) have a lower carbon
equivalent footprint, although they still
average 3–10 times greater than high-protein
plant foods (Fig.2). Pigs and poultry also
consume feed that could otherwise be more
eciently consumed directly by humans.
Moving forwards, there are steps
that governments and international
climate negotiators can take to curb
global ruminant increases and reduce
emissions from the agricultural sector.
Reducing meat consumption as a demand-
side mitigation action oers greater
greenhouse gas reduction potential
(0.7–7.3GtCO2eyr–1) than the supply-
side measures of increased crop yields
(0.2–1.9GtCO2eyr–1) or livestock feeding
eciency (0.2–1.6GtCO2eyr–1) (Table2
in ref.5). In terms of short-term climate
change mitigation during the next few
decades, if all the land used for ruminant
livestock production were instead converted
to grow natural vegetation, increased CO2
sequestration on the order of 30–470% of
the greenhouse gas emissions associated
with food production could be expected5,11.
Nonetheless, policies targeting both supply-
side measures to improve agricultural
production eciencies and demand-side
mitigation for encouraging behavioural
changes to reduce meat consumption
(particularly ruminant meat) and waste
have the best chance of providing rapid and
lasting climate benets5. Inuencing human
behaviour is one of the most challenging
aspects of any large-scale policy, and it is
unlikely that a large-scale dietary change
will happen voluntarily without incentives12.
Implementing a tax or emission trading
scheme on livestock’s greenhouse gas
emissions could be an economically sound
policy that would modify consumer prices
and aect consumption patterns12. A tax has
recently been successfully modelled for the
European Union with tax rates proportional
to the average greenhouse gas emissions
per unit of food sold10, although social
justice, equity and food access issues need
to be carefully considered. Such demand-
side mitigation measures have more
social and environmental co-benets than
supply-side measures5.
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0
Ruminants
Natural gas,
oil, industry
Landfills
and waste
Biomass
burning
Coal
Rice
Emissions (Gt CO
2
e yr
–1
)
4.0
3.8
3.6
3.4
3.2
3.0
2.8
2.6
2.4
2.2
2.0
Year
Billions of ruminants
N2O
0.17
Ozone-
depleting
substances
0.32
CH4
0.50
Other
0.01
CO2
1.7
1961197119811991 2001 2011
a
cd
Year
1980 2000 2020 2040 2060 2080 2100
4.0
1.5
2.0
2.5
3.0
3.5
Direct radiative forcing (W m
–2
)
bContinued
2008
emissions
80% cut in
non-CO2
80% cut in
CO2
80% cut in all
greenhouse gases
Figure 1 | Compound- and sector-specific emissions of greenhouse gases, associated radiative forcing
and global ruminant numbers over the past 50 years. a, Estimates of direct radiative forcing in 2008 for
CO2 and non-CO2 greenhouse gases from anthropogenic sources. b, Projections of radiative forcing in
four dierent scenarios: constant future emissions at 2008 levels (red); 80% reduction in only non-CO2
emissions (orange), 80% reduction in only CO2 emissions (blue), and 80% reductions in both non-CO2
and CO2 emissions (green). c, Estimated annual anthropogenic emissions from major sources of methane
in recent years. Error bars represent 1 standard deviation. d, Global ruminant numbers from 1961 to 2011.
Data for ac from ref.1, d from ref.2.
© 2014 Macmillan Publishers Limited. All rights reserved
4 NATURE CLIMATE CHANGE | VOL 4 | JANUARY 2014 | www.nature.com/natureclimatechange
opinion & comment
International climate negotiators
can take steps to reduce greenhouse gas
emissions from livestock as well as from the
burning of fossil fuels. So far, global climate
policy instruments have mainly focused on
engineering improved industrial processes,
energy eciency and investments in
alternative energy generation technologies,
because sustainability has been
predominantly interpreted as technological
progress rather than changed patterns of
human behaviour6. Continued growth of
ruminant meat consumption will represent
a major obstacle for reaching ambitious
climate change targets. e substantial
environmental and climate costs of
increased meat consumption have been
recognized by the United Nations Food
and Agriculture Organization4. However,
mitigation of greenhouse gas emissions
from ruminants has not received adequate
attention in negotiations under the United
Nations Framework Convention on
Climate Change13. Meeting documents
show that activities to reduce emissions
from ruminants and agriculture in general,
and in negotiations on land use, land-use
change and forestry and reducing emission
from deforestation and forest degradation
have been disproportionately slow13. e
land-use accounting under the Kyoto
Protocol provides insucient coverage
of land-based emissions considering
their large contributions to greenhouse
gas uxes. e Kyoto Protocol also only
covers industrialized countries, so it misses
some of the largest emerging ruminant
producers. Further, under Articles 3.3
and 3.4 of the Kyoto Protocol, emission
reduction commitments for cropland and
grazing land management are optional in
many situations14.
e above-presented evidence calls
for a more comprehensive approach to
accounting in the Agriculture, Forestry
and Other Land Use sector, following
the lead of those countries requesting
mandatory accounting for land-based
emissions, including cropland and grazing
land sectors14. Progress would be facilitated
if emissions resulting from ruminant
livestock production are placed on the
agenda of forthcoming global climate
meetings such as the annual sessions of the
Conference of the Parties. Current national
policies on mitigating climate change could
also be revised to curtail emissions from
ruminant livestock in both developed and
developing countries.
Because the Earth’s climate may be
near tipping points to major change, the
need to act is increasingly pressing15,16.
Lowering peak climate forcing quickly
with ruminant and CH4 reductions would
lessen the likelihood of irreversibly
crossing such tipping points into a new
climatic state1. Reducing the numbers of
ruminants will be a dicult and complex
task, both politically and socially. However,
decreasing ruminants should be considered
alongside our grand challenge of
signicantly reducing the world’s reliance
on fossil fuel combustion. Only with the
recognition of the urgency of this issue
and the political will to commit resources
to comprehensively mitigate both CO2 and
non-CO2 greenhouse gas emissions will
meaningful progress be made on climate
change. For an eective and rapid response,
we need to increase awareness among the
public and policymakers that what we
choose to eat has important consequences
for climate change.
William J.Ripple1*, Pete Smith2, Helmut Haberl3,4,
Stephen A.Montzka5, Clive McAlpine6 and
Douglas H.Boucher7 are at 1Department of Forest
Ecosystems and Society, Oregon State University,
Corvallis, Oregon, USA, 2Scottish Food Security
Alliance-Crops and Institute of Biological and
Environmental Sciences, University of Aberdeen,
Aberdeen AB24 3UU, UK, 3Institute of Social
Ecology Vienna, Alpen-Adria Universität
Klagenfurt, Wien, Graz, Schottenfeldgasse 29,
1070 Vienna, Austria, 4Humboldt-Universität
zu Berlin, Integrative Research Institute on
Transformations of Human-Environment Systems
(IRI THESys), Friedrichstraβe 191,D-10117 Berlin,
Ge rmany, 5National Oceanic and Atmospheric
Administration, Earth System Research Laboratory,
Boulder, Colorado 80305, USA, 6e University of
Queensland, School of Geography, Planning and
Environmental Management, Brisbane, Queensland
4072, Australia, 7Tropical Forest and Climate
Initiative, Union of Concerned Scientists,1825K
Street, NW Suite 800, Washington DC 20006, USA.
*e-mail: bill.ripple@oregonstate.edu
References
1. Montzka, S.A., Dlugokencky, E.J. & Butler, J.H. Nature
476, 43–50 (2011).
2. FAO ST AT (FAO, accessed 12 August 2013);
http://go.nature.com/Z23f7E
3. Gerber, P.J. et al. Tackling Climate Ch ange rough Livestock —
A Global Assessment of Emissions and Mitigation Oppor tunities
(FAO, 2013).
4. Steinfeld, H. et al. Livestock’s Long Shadow: Environmental Issues
and Options (FAO, 2006).
90
80
70
60
50
40
30
20
10
0
Beef (extensive)
Sheep
Beef meadow systems
Beef (intensive)
Seafood (fisheries)
Pork
Seafood (aquaculture)
Poultry
Eggs
Meat substitutes
(vegetal)
Pulses (beans, peas, soy)
Ruminant
Other
Carbon equivalent footprint
(kg CO2e per kg product)
Figure 2 | Average carbon equivalent footprint of protein-rich solid foods per kilogram of product from a
global meta-analysis of life-cycle assessment studies. Extensive beef involves cattle grazing across large
pastoral systems, whereas intensive beef typically involves feedlots. Meat substitutes are also known
as meat analogues, which are high-protein plant products that have aesthetic qualities (such as flavour,
texture, appearance) of specific types of meat. Error bars represent standard errors. Data from ref.17.
© 2014 Macmillan Publishers Limited. All rights reserved
NATURE CLIMATE CHANGE | VOL 4 | JANUARY 2014 | www.nature.com/natureclimatechange 5
opinion & comment
5. Smith, P. et al. Glob. Change Biol. 19, 2285–2302 (2013).
6. McAlpine, C.A., Etter, A., Fearnside, P.M., Seabrook, L. &
Lawrence, W.F. Glob. Environ. Change. 19, 21–33 (2009).
7. Beschta, R.L. et al. Environ. Manage. 51, 474–491(2012).
8. American Dietetic Association J. Am. Dietetic Assoc.
109, 1266–1282 (2009).
9. Fraser, G.E. Am. J. Clin. Nutr. 89(supplement), 1607S–1612S (2009).
10. Wirsenius, S., Hedenus, F. & Mohlin, K. Climatic Change
108, 159–184 (2011).
11. Schmidinger, K. & Stehfest, E. Int. J. Life Cycle Assess.
7, 962–972 (2012).
12. Popp, A. et al. Glob. Environ. Change 20, 451–462 (2010).
13. http://unfccc.int
14. Views on Land Use, Land-use Change and Forestry Issues Referred
to in Decision 2/CMP.7, Paragraphs 5-7. Submissions from Parties
and Admitted Observer Organizations 12–18 (SBSTA, UNFCCC,
2013); http://go.nature.com/hLAtTN
15. Lenton, T.M. Ambi o 41, 10–22 (2012).
16. Whiteman, G., Hope, C. & Wadhams, P. Nature
499, 401–403 (2013).
17. Nijdam, D., Rood, T. & Westhoek, H. Food Policy 37, 760–770 (2012).
Acknowledgements
We thank R. Lamplugh, B. Kauman, E. Stehfest and
R. Comforto for comments on an early dra of this
paper. W.R. was an Oregon State University L.L. Stewart
faculty scholar during this project. P.S. is a Royal
Society-Wolfson Research Merit Award holder. H.H.
gratefully acknowledges research funding from EU-FP7
(Volante, grant no. 265104) and the Austrian Science
Funds (project no. P20812-G11). S.A.M. acknowledges
the support of the NOAAs Climate Program Oce and
its Atmospheric Chemistry, Carbon Cycle and Climate
Program. C.M. is supported by the Australian Research
Council (FT100100338). D.B. thanks the Climate and Land
Use Alliance for its support of the Union of Concerned
Scientists’ Tropical Forest and Climate Initiative.
COMMENTARY:
Social learning and sustainable
development
Patti Kristjanson, Blane Harvey, Marissa Van Epp and Philip K. Thornton
To understand what social learning approaches can oer the sciences of adaptation and mitigation, we
need to assemble an appropriate evidence base.
Research-for-development institutions
such as the Food and Agriculture
Organization (FAO) of the UN,
CGIAR and their partners are under
mounting external pressure from donors
to link knowledge to actions that achieve
substantive, long-lasting and demonstrable
development outcomes1. If research is
genuinely to result in benecial changes in
behaviour, policies and institutions, research
outputs need to be much better informed
by and engaged with the processes through
which individuals, communities and
societies learn and adapt their behaviour
in the face of change2,3. Social learning
approaches may be able to contribute
substantially to this aim4. Denitions vary,
but in a nutshell social learning approaches
facilitate knowledge sharing, joint learning
and knowledge co-creation between diverse
stakeholders around a shared purpose,
taking learning and behavioural change
beyond the individual to networks and
systems. rough an iterative process of
working together — engaged in interactive
dialogue, exchange, learning, action,
reection and continuing partnership — new
shared ways of gaining knowledge emerge
that lead to changes in practice5. As such,
social learning builds on well-established
traditions from participatory development,
but puts learning and collective change at
the centre of engagement. Social learning
can provide a way to address complex
socio-ecological (so-called wicked)
problems by integrating diverse knowledge
and value systems at many dierent levels
and through dierent learning cycles.
From theory to practice
As a concept, social learning is appealing.
But how can we implement it as eectively
and eciently as possible? In practice, it
takes many dierent forms and can be
used to eect dierent types of change.
Some examples of innovative sustainable
agricultural development projects and
programmes that are taking this approach
are shown in Table1. ese illustrate a
range of scales at which social learning
and change are happening, from the
individual to the community to networks
and systems. e range of outcomes from
these projects is equally wide, from changes
in the way farmers go about their business
to new agricultural input distribution
systems to the creation of new institutions
and the empowerment of national
agricultural planners.
On the face of it, social learning
approaches should be able to
contribute to smarter, more eective
research-for-development institutions in
terms of performance and governance, and
also help them to achieve more sustainable
results, measured as development
outcomes6. We also know that iterative
learning processes are perceived to be
a critical component of adapting to
environmental change, and that there is
an absence of learning tools that can be
applied in contexts where uncertainty is
high7. But at the moment, we have only
limited evidence on the impact of social
learning approaches on tangible development
outcomes, and not much is known about
the costs of social learning approaches in
comparison with more traditional, linear
practices8. ere has been only limited
eort put into evaluating social learning
methods beyond one-o case studies and
post hoc or appreciative reections9,10.
Larger-scale reviews of social learning
have thus far focused on its framings and
methodologies more than on its ultimate
impacts. Scientists are particularly concerned
with the transaction costs that they perceive
to be high (for example, the amount of time
spent dealing with ‘messy partnerships’) and
a limited ability to replicate and scale up
results more broadly.
A framework for gathering evidence
In view of the limitations of the current
evidence base and calls for greater empirical
rigour in evaluating social learning11, we
are embarking on a systematic evidence-
gathering eort, using a common evaluative
framework to track new initiatives from
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... With the rapid development of the modern economy, the demand for high-protein food sources is increasing year by year, and beef, mutton, and dairy products (especially ruminant products) seem to be the first choice for most consumers [1,2]. However, ruminant production is one of the main drivers of global environmental degradation, and the contribution to environmental pollution is much greater compared with non-ruminants [3,4]. Ruminants account for over 70% of global livestock ammonia (NH 3 ) emissions and around 30% of total anthropogenic NH 3 emissions, resulting in significant economic losses and negative human health impacts [5,6]. ...
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Precision dietary interventions (e.g., altering proportions of dietary protein fractions) has significant implications for the efficiency of nutrient use in ruminants, as well as lowering their environmental footprint, specifically nitrogen (N) emissions. Soluble protein (SP) is defined as the protein fraction that is rapidly degraded in the rumen (e.g., non-protein N and true protein), and our previous study found that regulating SP levels could improve N efficiency in Hu sheep. Thus, the present study was conducted to explore in vitro how protein fractions with different SP levels modulate the rumen microbial community and its association with N metabolism. Four dietary treatments with different SP proportions and similar crude protein (CP) content (~14%) were formulated (% of CP): 20 (S20), 30 (S30), 40 (S40) and 50 (S50). Results showed that NH3-N content increased with increasing SP levels at 4, 12 and 24 h; TVFA, acetate, propionate and valerate were higher in S30 and S40 (p < 0.05) and had quadratic effects (p < 0.05). Moreover, dry matter digestibility (DMD) and N digestibility (ND) were all decreased with S20 and S50 (p < 0.05). The S30 and S40 treatments increased the abundance of Bacteroidetes and Prevotella (Prevotella_ruminicola) but decreased the abundance of Firmicutes and Proteobacteria (p < 0.05). Bacterial pathways related to amino acid and fatty acid metabolism also were enriched with S30 and S40. The abundance of Entodinium was increased with S30 and S40 and had a positive correlation with Prevotella, and these two genera also played an important role in N metabolism and VFA synthesis of this study. In conclusion, bacterial and protozoal communities were altered by the level of SP (% of CP), with higher SP levels (~50% of CP) increasing the microbial diversity but being detrimental to rumen N metabolism.
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Feed chemical composition is associated with methane (CH4) formation in the rumen, and thus CH4 yields (Ym; CH4 emitted from per unit of dry matter intake) could be predicted using near-infrared reflectance spectroscopy (NIRS) of feeds fed to ruminants. Two databases of NIRS data were compiled from feeds used in experiments in which CH4 yields had been quantified in respiration chambers. Each record in the databases represented a batch of feed offered to a group of experimental animals and the mean CH4 yield for the group. A near-infrared reflectance spectrum was obtained from each feed, and these spectra were used to generate a predictive equation for Ym. The predictive model generated from brassica crops and pasture fed at a similar feeding level (n = 40 records) explained 53% of the variation in Ym and had a reasonably good agreement (concordance correlation coefficient of 0.77). The predictive ability of the NIRS calibration could be useful for screening purposes, particularly for predicting the potential Ym of multiple feeds or feed samples, rather than measuring Ym in animal experiments at high expenses. It is recommended that the databases for NIRS calibrations are expanded by collecting feed information from future experiments in which methane emissions are measured, using alternative algorithms and combining other techniques, such as terahertz time-domain spectroscopy.
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This study tested the effect of normatively‐focused scientific consensus messages (NFSCMs) on receivers' intention to consume GE‐foods. In Study 1, the efficacy of a NFSCM was examined, relative to a standard descriptive norm message (SDNM), a scientific consensus message (SCM), and two control messages, issue‐relevant and issue‐irrelevant messages, using an experiment. In Study 2, the effect of the NFSCM with discrete descriptive norm formats was tested, relative to a standard message used in the real world, using an experiment. Results indicated that the effect of exposure to the NFSCM on intention was mediated via attentional focus on the norm information and perceptions about the norm, which is consistent with those in prior literature. The re‐specified model was not contingent on participants’ education level, gender and political stance indicating a uniform effect. Exposure to the messages also changed receivers’ feeling of disgust and un/certainty about the scientific issue in desirable ways.
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The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which causes COVID-19, emerged in late 2019, halfway through the preparation of the IPCC WGII Sixth Assessment Report. This Cross-Chapter Box assesses how the massive shock of the pandemic and response measures interact with climate-related impacts and risks as well as its significant implications for risk management and climate resilient development.
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Drought is a complicated natural hazard that has far-reaching social and environmental impacts. In Ethiopia's diverse agro ecological zones, drought remains a severe challenge and problem. Livestock rising is one of the agricultural sub-sectors that provide income and livelihood to around one-third of African inhabitants and accounts for 30-50 percent of agricultural GDP. Pastoralists on the Ethiopia-Kenya-Somalia border endured extreme suffering, including the loss of nearly 80% of their cattle and huge migration out of drought-stricken areas. Drought can cause severe economic hardship and stress for farmers and local economies, like; lost productivity, population reduction, and the trauma of witnessing livestock, crops, soil, and native vegetation damage. Between 1990 and 2000, and 2001-2002/03, drought-related animal death rates in the Somali region increased by 60% and 80% of the entire cattle population, respectively. Drought has the greatest immediate effects on farmers, including depletion of water resources, crop failure, and an increase in food prices, ill health, livestock output losses and death, and a decline in livestock prices in the Borana zone. Drought adaptation and mitigation measures depending on geography and livestock system may improve the study's trajectory in the future if further review is done. ARTICLE HISTORY
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Increasing worldwide demand for beef products promotes international beef trade. Cattle raising and beef products as significant sources of methane (CH4) emissions have received widespread concerns. However, the factors driving CH4 emissions embodied in the global beef trade have not been quantified. Here, we evaluate international beef trade-induced CH4 emissions and assess the contribution of the five driving factors to changes in CH4 emissions embodied in the beef trade from 2000 to 2018. We show that driven by increasing population and meat demands, the global beef trade-induced CH4 emissions increased continuously in the past two decades, with total emissions of 9337.3 Gg in 2018. The drivers that could potentially reduce trade-related emissions are emission intensities in beef exporting countries and beef importing countries' selections of their beef suppliers. Together, these two driving factors reduced CH4 emissions by 923.5 Gg from 2012 to 2018. Results suggest that efforts should be made to reduce the emission intensity via improving cattle feed and feeding practices in beef exporting countries. Beef importing countries could also contribute to CH4 emission reduction by selecting those beef exporting countries with low emission intensities.
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Significance Agricultural methane emissions must be decreased by 11 to 30% of the 2010 level by 2030 and by 24 to 47% by 2050 to meet the 1.5 °C target. We identified three strategies to decrease product-based methane emissions while increasing animal productivity and five strategies to decrease absolute methane emissions without reducing animal productivity. Globally, 100% adoption of the most effective product-based and absolute methane emission mitigation strategy can meet the 1.5 °C target by 2030 but not 2050, because mitigation effects are offset by projected increases in methane. On a regional level, Europe but not Africa may be able to meet their contribution to the 1.5 °C target, highlighting the different challenges faced by high- and middle- and low-income countries.
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Grassland accounts for a high proportion of the agricultural area of the United Kingdom, but the significance of its contribution to the nation’s food supply has been questioned. Using representative figures for the composition of UK ruminant livestock diets, we estimated the total production of human-edible protein from grass and forage crops consumed by cattle and sheep. We found that this equates to 21.5 g of protein per person per day, of which 15.2 g comes from milk, 4.71 g from beef and 1.60 g from sheep meat. This represents 45% of the total amount of human-edible animal protein produced in the UK (46.6 g/head) and is equivalent to one-third of the recommended adult human daily protein intake of 64 g/head. Given the growing pressure to produce food in a more resource-efficient manner, grasslands have a valuable role to play in providing food alongside multiple public goods.
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In recent years, animal husbandry has aimed at improving the conditions of livestock animals useful for humans to solve environmental and health problems. The formulation of animal feeds or supplements based on antioxidant plant compounds is considered a valuable approach and an alternative for livestock productivity. Forest biomass materials are an underestimated source of polyphenolic compounds whose sustainable recovery could provide direct benefits to animals and, indirectly, human nutrition. In this context, an alcohol extract from leaves of Fagus sylvatica L. was first investigated through an untargeted ultra-high-performance liquid chromatography–high-resolution tandem mass spectrometry (UHPLC-HRMS/MS) approach. Then, it was fractionated into a fatty acid-rich and a polyphenolic fraction, as evidenced by total lipid, phenol, and flavonoid content assays, with antiradical and reducing activity positively correlated to the latter. When tested in vitro with rumen liquor to evaluate changes in the fermentative parameters, a significant detrimental effect was exerted by the lipid-rich fraction, whereas the flavonoid-rich one positively modulated the production of volatile fatty acids (i.e., acetate, butyrate, propionate, etc.).
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Feeding nine to ten billion people by 2050 and preventing dangerous climate change are two of the greatest challenges facing humanity. Both challenges must be met whilst reducing the impact of land management on ecosystem services that deliver vital goods and services, and support human health and well-being. Few studies to date have considered the interactions between these challenges. In this study we briefly, outline the challenges, review the supply- and demand-side climate mitigation potential available in the Agriculture, Forestry and Other Land Use (AFLOU) sector, and options for delivering food security. We briefly outline some of the synergies and trade-offs afforded by mitigation practices, before presenting an assessment of the mitigation potential possible in the AFOLU sector under possible future scenarios in which demand-side measures co-delivery to aid food security. We conclude that whilst supply-side mitigation measures, such as changes in land management, might either enhance or negatively impact food security, demand-side mitigation measures, such as reduced waste or demand for livestock products, should benefit both food security and greenhouse gas (GHG) mitigation. Demand-side measures offer a greater potential (1.5-15.6 Gt CO2 -eq. yr(-1) ) in meeting both challenges than do supply-side measures (1.5-4.3 Gt CO2 -eq. yr(-1) at carbon prices between 20 and 100 US$ tCO2 -eq.(-1) ), but given the enormity of challenges, all options need to be considered. Supply-side measures should be implemented immediately, focussing on those that allow the production of more agricultural product per unit of input. For demand-side measures, given the difficulties in their implementation and lag in their effectiveness, policy should be introduced quickly, and should aim to co-deliver to other policy agendas, such as improving environmental quality, or improving dietary health. These problems facing humanity in the 21(st) Century are extremely challenging, and policy that addresses multiple objectives is required now more than ever. © 2013 Blackwell Publishing Ltd.
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Climate change affects public land ecosystems and services throughout the American West and these effects are projected to intensify. Even if greenhouse gas emissions are reduced, adaptation strategies for public lands are needed to reduce anthropogenic stressors of terrestrial and aquatic ecosystems and to help native species and ecosystems survive in an altered environment. Historical and contemporary livestock production-the most widespread and long-running commercial use of public lands-can alter vegetation, soils, hydrology, and wildlife species composition and abundances in ways that exacerbate the effects of climate change on these resources. Excess abundance of native ungulates (e.g., deer or elk) and feral horses and burros add to these impacts. Although many of these consequences have been studied for decades, the ongoing and impending effects of ungulates in a changing climate require new management strategies for limiting their threats to the long-term supply of ecosystem services on public lands. Removing or reducing livestock across large areas of public land would alleviate a widely recognized and long-term stressor and make these lands less susceptible to the effects of climate change. Where livestock use continues, or where significant densities of wild or feral ungulates occur, management should carefully document the ecological, social, and economic consequences (both costs and benefits) to better ensure management that minimizes ungulate impacts to plant and animal communities, soils, and water resources. Reestablishing apex predators in large, contiguous areas of public land may help mitigate any adverse ecological effects of wild ungulates.
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Agriculture is responsible for 25–30% of global anthropogenic greenhouse gas (GHG) emissions but has thus far been largely exempted from climate policies. Because of high monitoring costs and comparatively low technical potential for emission reductions in the agricultural sector, output taxes on emission-intensive agricultural goods may be an efficient policy instrument to deal with agricultural GHG emissions. In this study we assess the emission mitigation potential of GHG weighted consumption taxes on animal food products in the EU. We also estimate the decrease in agricultural land area through the related changes in food production and the additional mitigation potential in devoting this land to bioenergy production. Estimates are based on a model of food consumption and the related land use and GHG emissions in the EU. Results indicate that agricultural emissions in the EU27 can be reduced by approximately 32 million tons of CO2-eq with a GHG weighted tax on animal food products corresponding to €60 per ton CO2-eq. The effect of the tax is estimated to be six times higher if lignocellulosic crops are grown on the land made available and used to substitute for coal in power generation. Most of the effect of a GHG weighted tax on animal food can be captured by taxing the consumption of ruminant meat alone.
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While the global community is seeking to reduce fossil fuel consumption, a parallel but equally important issue is the environmental impacts of increased world consumption of beef. We provide a comparative analysis and synthesis of the expansion of beef cattle production and its regional and global environmental impacts for Queensland (Australia), Colombia and Brazil. Evidence assembled indicates that rising beef consumption is a major driver of regional and global change, and warrants greater policy attention. We propose four policy imperatives to help mitigate escalating environmental impacts of beef: stop subsidising beef production and promoting beef consumption; control future expansion of soybeans and extensive grazing; protect and restore regrowth forests in grazing lands; and allocate resources to less environmentally damaging alternative land uses.
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Methane released by melting permafrost will have global impacts that must be better modelled, say Gail Whiteman, Chris Hope and Peter Wadhams.
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Purpose Until recently, life cycle assessments (LCAs) have only addressed the direct greenhouse gas emissions along a process chain, but ignored the CO2 emissions of land-use. However, for agricultural products, these emissions can be substantial. Here, we present a new methodology for including the implications of land occupation for CO2 emissions to realistically reflect the consequences of consumers’ decisions. Method In principle, one can distinguish five different approaches of addressing the CO2 consequences of land occupation: (1) assuming constant land cover, (2) land-use change related to additional production of the product under consideration, (3) historic land-use change, assuming historical relations between existing area and area expansion (4) land-use change related to less production of the product under consideration (“missed potential carbon sink” of land occupation), and (5) an approach of integrating land conversion emissions and delayed uptake due to land occupation. Approach (4) is presented in this paper, using LCA data on land occupation, and carbon dynamics from the IMAGE model. Typically, if less production occurs, agricultural land will be abandoned, leading to a carbon sink when vegetation is regrowing. This carbon sink, which does not occur if the product would still be consumed, is thus attributed to the product as “missed potential carbon sink”, to reflect the CO2 implications of land occupations. Results We analyze the missed potential carbon sink by relating land occupation data from LCA studies to the potential carbon sink as calculated by an Integrated Global Assessment Model and its process-based, spatially explicit carbon cycle model. Thereby, we account for regional differences, heterogeneity in land-use, and different time horizons. Example calculations for several livestock products show that the CO2 consequences of land occupation can be in the same order of magnitude as the other process related greenhouse gas emissions of the LCA, and depend largely on the production system. The highest CO2 implications of land occupation are calculated for beef and lamb, with beef production in Brazil having a missed potential carbon sink more than twice as high as the other GHG emissions. Conclusions Given the significant contribution of land occupation to the total GHG balance of agricultural products, they need to be included in life cycle assessments in a realistic way. The new methodology presented here reflects the consequences of producing or not producing a certain commodity, and thereby it is suited to inform consumers fully about the consequences of their choices.
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There is widespread concern that anthropogenic global warming will trigger Arctic climate tipping points. The Arctic has a long history of natural, abrupt climate changes, which together with current observations and model projections, can help us to identify which parts of the Arctic climate system might pass future tipping points. Here the climate tipping points are defined, noting that not all of them involve bifurcations leading to irreversible change. Past abrupt climate changes in the Arctic are briefly reviewed. Then, the current behaviour of a range of Arctic systems is summarised. Looking ahead, a range of potential tipping phenomena are described. This leads to a revised and expanded list of potential Arctic climate tipping elements, whose likelihood is assessed, in terms of how much warming will be required to tip them. Finally, the available responses are considered, especially the prospects for avoiding Arctic climate tipping points.