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Animal
Feed
Science
and
Technology
166–
167 (2011) 779–
782
Contents
lists
available
at
ScienceDirect
Animal
Feed
Science
and
Technology
journal
homepage:
www.elsevier.com/locate/anifeedsci
Livestock
and
greenhouse
gas
emissions:
The
importance
of
getting
the
numbers
right
M.
Herreroa,∗,
P.
Gerberb,
T.
Vellingac,
T.
Garnettd,
A.
Leipe,
C.
Opiob,
H.J.
Westhoekf,
P.K.
Thorntona,
J.
Oleseng,
N.
Hutchingsg,
H.
Montgomeryh,j,
J.-F.
Soussanai,
H.
Steinfeldb,
T.A.
McAllisterj
aInternational
Livestock
Research
Institute,
PO
Box
30709,
Nairobi,
Kenya
bFood
and
Agriculture
Organization
of
the
United
Nations,
Animal
Production
and
Health
Division,
Rome,
Italy
cWageningen
University
and
Research
Centre,
Animal
Science
Group,
Wageningen,
The
Netherlands
dFood
Climate
Research
Network,
Centre
for
Environmental
Strategy,
University
of
Surrey,
Guildford,
Surrey,
UK
eEuropean
Commission,
Joint
Research
Centre,
Institute
for
Environment
and
Sustainability,
Ispra
(VA),
Italy
fNetherlands
Environmental
Assessment
Agency
(PBL),
Bilthoven,
The
Netherlands
gAarhus
University,
Department
of
Agroecology
and
Environment,
Tjele,
Denmark
hMinistry
of
Agriculture
and
Forestry,
Wellington,
New
Zealand
iInstitute
Nationale
de
la
Recherche
Agronomique,
Clermont-Ferrand,
France
jAgriculture
and
Agri-Food
Canada,
Lethbridge
Research
Centre,
Alberta,
Canada
a
r
t
i
c
l
e
i
n
f
o
Keywords:
Greenhouse
gas
Livestock
Methane
Carbon
dioxide
Inventory
a
b
s
t
r
a
c
t
Estimates
of
global
greenhouse
gases
(GHG)
emissions
attributable
to
livestock
range
from
8
to
51%.
This
variability
creates
confusion
among
policy
makers
and
the
public
as
it
sug-
gests
that
there
is
a
lack
of
consensus
among
scientists
with
regard
to
the
contribution
of
livestock
to
global
GHG
emissions.
In
reality,
estimates
of
international
scientific
organiza-
tions
such
as
the
International
Governmental
Panel
on
Climate
Change
(IPCC)
and
the
Food
and
Agriculture
Organization
(FAO)
are
in
close
agreement,
with
variation
mainly
arising
on
how
GHG
emissions
are
allocated
to
land
use
and
land
use
change.
Other
estimates
involve
major
deviations
from
international
protocols,
such
as
estimated
global
warming
potential
of
CH4or
including
respired
CO2in
GHG
emissions.
These
approaches
also
fail
to
differenti-
ate
short-term
CO2arising
from
oxidation
of
plant
C
by
ruminants
from
CO2released
from
fixed
fossil
C
through
combustion.
These
deviances
from
internationally
accepted
proto-
cols
create
confusion
and
direct
attention
from
anthropomorphic
practices
which
have
the
most
important
contribution
to
global
GHG
emissions.
Global
estimates
of
livestock
GHG
emissions
are
most
reliable
when
they
are
generated
by
internationally
recognized
scien-
tific
panels
with
expertise
across
a
range
of
disciplines,
and
with
no
preconceived
bias
to
particular
outcomes.
This
paper
is
part
of
the
special
issue
entitled:
Greenhouse
Gases
in
Animal
Agriculture
–
Finding
a
Balance
between
Food
and
Emissions,
Guest
Edited
by
T.A.
McAllister,
Section
Guest
Editors;
K.A.
Beauchemin,
X.
Hao,
S.
McGinn
and
Editor
for
Animal
Feed
Science
and
Technology,
P.H.
Robinson.
Crown Copyright ©
2011 Published by Elsevier B.V. All rights reserved.
Abbreviations:
FAO,
Food
and
Agriculture
Organization;
GHG,
greenhouse
gases;
GWP,
global
warming
potential;
IPCC,
Intergovernmental
Panel
on
Climate
Change.
∗Corresponding
author.
Tel.:
+254
20
422
3000;
fax:
+254
20
422
3001.
E-mail
address:
m.herrero@cgiar.org
(M.
Herrero).
0377-8401/$
–
see
front
matter.
Crown Copyright ©
2011 Published by Elsevier B.V. All rights reserved.
doi:10.1016/j.anifeedsci.2011.04.083
780 M.
Herrero
et
al.
/
Animal
Feed
Science
and
Technology
166–
167 (2011) 779–
782
1.
Introduction
Livestock
farming
plays
a
critical
role
in
global
food
production,
and
has
formed
part
of
local
landscapes
and
ecosystems
for
millennia.
The
importance
of
livestock
in
providing
human
societies
with
food,
incomes,
employment,
nutrients
and
risk
insurance
is
widely
recognized
(Perry
and
Sones,
2007;
Herrero
et
al.,
2009).
At
the
same
time
there
is
a
growing
awareness
within
the
research
and
policy
communities
that
rapid
growth
in
global
production
and
consumption
of
livestock
products
is
contributing
to
a
range
of
serious
environmental
problems,
the
most
notable
being
the
sector’s
substantial
contribution
to
climate
changing
emissions.
In
2006,
using
well
documented
and
rigorous
life
cycle
analyses,
it
was
estimated
that
livestock
contributed
18%
of
global
greenhouse
gas
(GHG)
emissions
(FAO,
2006).
According
to
this
study,
the
main
sources
of
GHG
from
livestock
systems
arise
from
land
use
change
(CO2),
enteric
fermentation
from
ruminants
(CH4)
and
manure
management
(N2O).
A
recent
non-peer
reviewed
report
published
by
the
Worldwatch
Institute
(Goodland
and
Anhang,
2009)
contested
these
figures
and
argued
that
GHG
emissions
from
livestock
are
closer
to
51%
of
global
GHG
emissions.
In
our
view,
this
report
has
oversimplified
the
issue
with
respect
to
livestock
production
while
emphasizing
negative
impacts
of
livestock
on
the
environment
and
ignoring
positives.
In
so
doing
it
used
a
flawed
methodological
approach
to
estimate
GHG
emissions
from
livestock.
Even
though
Goodland
and
Anhang
(2009)
do
not
present
detailed
methodologies
or
clear
scientific
evidence
to
back
their
results,
differences
between
their
approach
and
internationally
accredited
approaches
arise
in
the
following
areas.
2.
Exclusion
of
carbon
dioxide
emissions
from
livestock
respiration
According
to
Goodland
and
Anhang
(2009),
CO2from
livestock
respiration
was
an
overlooked
source
of
GHG
from
the
FAO
study
(2006).
Under
Intergovernmental
panel
on
climate
change
inventory
guidelines
(IPCC,
2006),
and
under
the
Kyoto
protocol,
CO2from
livestock
is
not
considered
a
net
source
of
CO2because
this
CO2is
considered
to
be
part
of
a
rapid
biological
system
where
plant
material
consumed
by
the
animals
is
created
by
photosynthesis,
sequestering
CO2in
the
process.
The
amount
of
C
in
feed
consumed,
and
CO2emitted
by
livestock,
are
considered
to
be
broadly
equivalent
and
part
of
the
short
term
C
cycle
resulting
in
no
net
increase
in
the
concentration
of
atmospheric
CO2within
relevant
time
horizons.
In
addition,
while
it
is
true
that
in
some
livestock
production
systems
the
balance
between
C
consumed
and
CO2emitted
is
not
perfectly
equal,
these
differences
are
small
when
overall
global
rangeland
and
forage
productivity
are
considered
as
a
C
sink.
There
is
also
a
substantive
body
of
evidence,
which
suggests
that
grasslands
and
their
growth
more
than
offset
CO2emissions
from
livestock
(Fisher
et
al.,
1994;
IPCC,
2006).
Regardless,
if
respiration
is
accounted
for,
then
CO2absorption
related
to
plant
growth
must
also
be
considered
in
the
overall
C
cycle
analysis.
3.
Emissions
from
land
use
and
land
use
change
Goodland
and
Anhang
(2009)
claim
that
emissions
from
land
use
and
land
use
change
induced
by
the
livestock
sector
have
been
grossly
underestimated.
While
estimates
from
FAO
(2006)
may
be
conservative
in
many
aspects,
the
argument
and
analysis
presented
by
the
authors
raises
some
questions.
Firstly,
in
estimating
the
‘unaccounted
for
emissions’
from
land
use
and
land
use
change,
the
authors
utilize
a
different
approach
from
the
FAO
report
(2006).
The
authors
use
a
consequential
approach
that
applies
a
‘what-if
scenario’
in
estimation
of
emissions
from
land
use,
and
then
assess
the
potential
emission
reductions
arising
from
use
of
land
for
alternative
practices.
In
other
words,
it
quantifies
the
amount
of
C
that
would
be
sequestered
if
existing
grazing
lands
were
allowed
to
revert
to
forest,
and
then
attributes
the
‘lost’
opportunity
for
C
sequestration
to
livestock
production.
The
FAO
assessment
(2006),
in
contrast,
bases
its
analysis
on
actual
land
use
trends,
thereby
allocating
C
losses
resulting
from
current
changes
in
land
use
to
livestock
production.
While
in
a
land
constrained
world
it
is
important
to
consider
different
future
possible
uses
for
land
so
as
to
ensure
food
security,
C
storage
and
biological
diversity,
the
approach
adopted
by
Goodland
and
Anhang
(2006)
is
methodologically
inconsistent.
The
authors
do
not
quantify
the
lost
opportunity
for
C
sequestration
that
results
from
other
forms
of
land
use,
such
as
arable
crop
production
for
human
consumption,
or
urban
development.
If
they
were
to
do
this,
then
overall
anthropogenic
GHG
emissions
would
be
higher,
and
livestock
related
impacts
would
need
to
be
seen
as
a
proportion
of
this
higher
figure.
More
importantly,
Goodland
and
Anhang
(2006)
advocate
that
livestock
products
be
replaced
with
alternative
food
sources,
a
strategy
which
would
require
a
portion
of
the
grazing
land
used
for
forage
production
to
be
converted
to
land
for
annual
crop
production
for
use
as
food
or
as
a
substrate
for
biofuel
production.
This
practice
would
contribute
to
habitat
destruction
of
native
grasslands,
an
ecosystem
which
harbors
a
number
of
at
risk
species.
Furthermore,
the
authors
fail
to
provide
detailed
analysis
on
which
alternative
protein
sources
would
replace
animal
protein
and
what
would
be
the
likely
implications
in
terms
of
land
use,
land
use
intensity,
food
security,
human
nutrition
and
livelihoods.
Goodland
and
Anhang’s
(2006)
proposal
to
convert
grazing
land
to
cultivated
land
for
biofuel
production
is
also
misleading
from
a
land
use
change
perspective.
In
a
hypothetical
world
without
livestock,
there
could
be
many
potential
uses
for
land
currently
utilized
for
livestock.
Land
use
would
depend
on
alternative
opportunity
costs,
labour
and
transport,
as
well
as
other
factors,
none
of
which
have
been
considered
systematically
by
Goodland
and
Anhang
(2006).
At
the
same
time,
in
most
cases
livestock
occupy
large
areas
of
the
world
where
other
forms
of
agriculture
are
impractical,
whether
for
producing
plant
based
human
foods,
biofuels
or
for
other
uses.
In
addition,
Goodland
and
Anhang
(2006)
erroneously
assume
that
biofuel
M.
Herrero
et
al.
/
Animal
Feed
Science
and
Technology
166–
167 (2011) 779–
782 781
production
is
GHG
neutral
(Searchinger
et
al.,
2008).
This
limits
their
scenario
of
growing
biofuels
in
all
areas
occupied
by
livestock.
Production
of
alternative
biofuels
may
be
limited
to
areas
which
are
close
to
markets
and
that
possess
adequate
infrastructure,
but
even
these
areas
would
have
competing
land
uses
and
substantial
opportunity
costs.
Removal
of
domesticated
ruminants
would
also
have
implications
with
regard
to
populations
of
wild
ungulates,
as
wild
ungulate
species
could
prevail
in
vacated
niches.
In
some
instances
GHG
emissions
from
wild
ruminants
may
be
even
higher
than
from
domesticated
ruminants
that
have
been
selected
over
generations
for
efficiency.
These
facts
point
to
the
reality
that
estimating
emissions
from
livestock
systems
is
very
complex
and
needs
to
be
assessed
with
solid
conceptual
models
of
global
environmental,
social
and
economic
change.
Goodland
and
Anhang
(2006)
also
omit
to
acknowledge
that
many
key
drivers
of
land
use
and
land
use
change,
such
as
deforestation,
are
outside
of
productive
land
uses
and
are
driven
by
motivations
and
policies
such
as
infrastructure
development,
land
speculation,
urbanization
and
development
of
renewable
energy.
Many
of
these
policies
are
driven
by
a
lack
of
economic
incentive
to
conserve
or
maintain
natural
resources.
4.
Global
warming
potential
of
methane
Goodland
and
Anhang
(2006)
suggest
use
of
a
20
yr
global
warming
potential
(GWP)
for
CH4of
72.
The
debate
on
how
much
warming
that
CH4causes
is
an
ongoing
one
(Shindell
et
al.,
2009).
Scientific
advancements
have
led
to
corrections
in
CH4GWP
values
over
the
past
decade.
Indeed
the
IPCC,
in
its
4th
Assessment
Report,
effectively
revised
the
global
warming
potential
from
23
to
25
as
indirect
effects
of
CH4on
ozone
and
stratospheric
water
vapor
were
included.
It
should
be
noted
that,
at
the
time
of
the
writing
of
the
2006
FAO
report,
the
GWP
of
23
over
a
100
yr
time
horizon
was
considered
valid
and
acceptable.
As
CH4has
an
atmospheric
lifetime
of
12
yr,
in
the
short
term
it
contributes
more
to
current
global
warming
than
the
factor
25
suggests,
but
this
effect
decays
almost
completely
after
a
period
of
20–30
yrs.
Consequently,
CH4is
a
very
important
gas
to
target
for
short
term
reduction
in
radiative
forcing.
However,
the
GWP
is
a
measure
to
prioritize
mitigation
practices,
for
which
the
scale
of
a
century
is
currently
considered
appropriate,
although
still
under
debate
(Shindell
et
al.,
2009).
The
IPCC
has
acknowledged
the
value
of
alternative
metrics
(e.g.,
Global
Temperature
Potential)
and
indicated
that
further
research
is
required
(Plattner
et
al.,
2009).
Selection
of
a
time
horizon
is
a
scientific
relevant
issue,
but
also
a
political
one
based
on
the
relative
weight
given
to
short
versus
long
lived
GHG.
5.
Attribution
of
greenhouse
gases
to
livestock
Goodland
and
Anhang
(2006)
identify
a
number
of
GHG
sources
currently
excluded
from
GHG
assessments
from
live-
stock.
Of
particular
importance
are
issues
related
to
the
complexity
of
attributing
certain
emissions
to
the
livestock
sector.
For
example
cooking
in
open
fires,
waste
management,
use
of
toxic
chemicals,
packaging
and
temperature
controlled
supply
chains,
and
the
occurrence
of
chronic
degenerative
diseases,
are
aspects
that
do
not
only
relate
to
production
and
consump-
tion
of
livestock
products.
Methodologies
for
estimating
and
adequately
attributing
these
kinds
of
emissions
to
specific
sectors
are
still
under
development
and
have
not
been
vetted
by
the
international
scientific
community.
Goodland
and
Anhang
(2006)
point
out
that
the
FAO
18%
estimate
lacks
relevance
and
is
outdated.
The
authors
erroneously
assume
that
a
12%
increase
in
global
tonnage
of
livestock
products
translates
into
a
proportionate
increase
in
GHG
emissions.
This
ignores
the
reality
that
production
systems
can
become
more
efficient
at
higher
production
levels.
For
example
in
Europe
(EU-12),
livestock
production
increased
slightly
between
1990
and
2002,
while
emissions
of
CH4and
N2O
decreased
8–9%
(EA,
2009).
Some
European
countries
have
seen
even
more
dramatic
improvements
in
efficiencies.
Denmark
reduced
its
emissions
of
CH4and
N2O
by
23%
from
1990
to
2002,
while
maintaining
dairy
production
output
and
increasing
pig
production
by
27%
(Danish
Environmental
Protection
Agency,
2005).
Increased
production
per
animal
led
to
a
reduction
in
livestock
populations,
and
more
efficient
use
of
manures
and
N
fertilizers.
Goodland
and
Anhang
(2006)
cite
use
of
unrealistically
low
population
estimates
of
livestock
in
estimation
of
GHG,
and
failure
to
use
a
correction
factor
to
account
for
growing
livestock
populations,
as
one
of
the
shortfalls
of
the
2006
FAO
report.
Specific
reference
is
made
to
production
of
33
million
poultry
worldwide.
This,
however,
stems
from
a
misinterpretation
on
the
part
of
the
authors
who
confuse
‘poultry
biomass’
with
production
of
poultry
meat
and,
despite
some
shortcomings
of
FAO
statistics,
it
remains
the
only
globally
recognized
source
of
GHG
data
on
agriculture.
Goodland
and
Anhang
(2006)
correctly
point
out
that
the
FAO
assessment
(2006)
omit
emissions
related
to
preparation
of
animal
products,
and
that
estimates
for
land
use
change,
transport
and
processing
are
deliberately
conservative.
These
methodological
decisions
were
constrained
by
availability
of
data
from
a
global
perspective
in
2006.
6.
Conclusions
Livestock
production
needs
to
be
considered
as
the
global
community
seeks
to
address
the
challenge
of
climate
change.
The
magnitude
of
the
discrepancy
between
the
Goodland
and
Anhang
paper
(2006)
and
widely
recognized
estimates
of
GHG
from
livestock
illustrates
the
need
to
provide
the
climate
change
community
and
policy
makers
with
accurate
emissions
estimates
and
information
about
the
link
between
agriculture
and
climate.
Improving
the
quality
of
the
global
estimates
of
GHG
attributed
to
livestock
systems
is
of
paramount
importance,
not
only
because
we
need
to
define
the
magnitude
of
the
impact
of
livestock
on
climate
change,
but
also
because
we
need
to
understand
their
contribution
relative
to
other
782 M.
Herrero
et
al.
/
Animal
Feed
Science
and
Technology
166–
167 (2011) 779–
782
sources.
Such
information
will
enable
effective
mitigation
strategies
to
be
designed
to
reduce
GHG
emissions
and
improve
sustainability
of
the
livestock
sector
while
continuing
to
provide
livelihoods
and
food
for
humans.
We
need
to
understand
where
livestock
can
help
and
where
they
hinder
the
goals
of
resilient
global
ecosystems
and
livelihoods
to
ensure
that
they
contribute
to
a
sustainable
future.
We
believe
these
efforts
need
to
be
part
of
an
ongoing
process,
but
one
which
is
conducted
through
transparent
well
established
methodologies,
rigorous
science
and
open
scientific
debate.
Only
in
this
way
will
we
be
able
to
advance
the
debate
on
livestock
and
climate
change
and
inform
policy,
climate
change
negotiations
and
public
opinion
more
accurately.
Conflict
of
interest
None.
References
Danish
Environmental
Protection
Agency,
2005.
Denmark’s
Fourth
National
Communication
on
Climate
Change
under
the
United
Nations
Framework
Convention
on
Climate
Change.
Environmental
Protection
Agency,
Danish
Ministry
of
the
Environment,
Copenhagen,
Denmark.
EA,
2009.
Annual
European
Community
greenhouse
gas
inventory
1990–2007
and
inventory
report
2009.
Submission
to
the
UNFCCC
secretariat,
European
Environment
Agency,
Brussels,
Belgium.
FAO,
2006.
Livestock’s
Long
Shadow.
Environmental
Issues
and
Options.
Food
and
Agriculture
Organization
of
the
United
Nations,
Rome,
Italy.
Fisher,
M.J.,
Rao,
I.M.,
Ayarza,
M.A.,
Lascano,
C.E.,
Sanz,
J.I.,
Thomas,
R.J.,
Vera,
R.R.,
1994.
Carbon
storage
by
introduced
deep-rooted
grasses
in
the
South
American
savannas.
Nature
371,
236–238.
Goodland,
R.,
Anhang,
J.,
2009.
Livestock
and
Climate
Change.
What
if
the
key
actors
in
climate
change
were
pigs,
chickens
and
cows?
Worldwatch
November/December
2009,
Worldwatch
Institute,
Washington,
DC,
USA,
pp.
10–19.
Herrero,
M.,
Thornton,
P.K.,
Gerber,
P.,
Reid,
R.S.,
2009.
Livestock,
livelihoods
and
the
environment:
understanding
the
trade-offs.
Curr.
Opin.
Environ.
Sustain.
1,
111–120.
IPCC,
2006.
IPCC
Guidelines
for
National
Greenhouse
Gas
Inventories.
Intergovernmental
Panel
on
Climate
Change,
NGGIP
Publications,
IGES,
Japan.
Perry,
B.,
Sones,
K.,
2007.
Poverty
reduction
through
animal
health.
Science
315,
333–334.
Plattner,
G-K.,
Stocker,
T.,
Midgley,
P.,
Tignor,
M.
(Eds.),
2009.
IPCC
Expert
Meeting
on
the
Science
of
Alternative
Metrics.
Intergovernmental
Panel
on
Climate
Change,
Geneva,
Switzerland.
European
Environment
Agency
Annual
European
Community
greenhouse
gas
inventory
1990–2007
and
inventory
report
2009.
Submission
to
the
UNFCCC
secretariat,
European
Environment
Agency,
Brussels,
Belgium.
Searchinger,
T.,
Heimlich,
R.,
Houghton,
R.A.,
Dong,
F.,
Elobeid,
A.,
Fabiosa,
J.,
Tokgoz,
S.,
Hayes,
D.,
Yu,
T.-H.,
2008.
Greenhouse
gases
through
emissions
from
use
of
U.S.
croplands
for
biofuels
increases
land-use
change.
Science
319,
1238.
Shindell,
D.T.,
Faluvegi,
G.,
Koch,
D.M.,
Schmidt,
G.A.,
Unger,
N.,
Bauer,
S.E.,
2009.
Improved
attribution
of
climate
forcing
to
emissions.
Science
326,
716–718.
