Enteric methane emission factors, total emissions and intensities from
Germany's livestock in the late 19th century: A comparison with the today's
emission rates and intensities
Research Institute for Farm Animal Research (FBN), Institute of Nutritional Physiology “Oskar Kellner”, Wilhelm-Stahl-Allee 2, 18196 Dummerstorf, Germany
Research Institute for Farm Animal Research (FBN), Wilhelm-Stahl-Allee 2, 18196 Dummerstorf, Germany
HIGHLIGHTS GRAPHICAL ABSTRACT
•Historic enteric CH
emission factors are
greatest for adult male cattle.
emission from German live-
stock was 898 kt in 1883 and 1061 kt in
•Compared to 1892, Germany's livestock
has been emitting less enteric CH
emission intensities for meat and
milk decreased from 1883 to 2020.
•Animal performance gain reduced CH
emission intensities over the years.
Editor: Jay Gan
Dry matter intake
In its climate protection law, Germany pursues the aim of achieving greenhouse gas neutrality by 2045. To approach
this aim, the emissions from allsectors shall be reduced by 65 % by 2030 relative to 1990 and this includes mitigation
of enteric methane (CH
) emissions from livestock. The enteric CH
emission rate must be reduced to 853 kt CH
2030, but if this target rate reaches the level of the pre-agroindustrial era remains to be evaluated. The present
study aimedto determine enteric CH
emissionfactors, emission rates and intensities forGermany in the 19th century.
Historical data about animal numbers in the German Empire were normalized to Germany's current territory. Body
weight and performance data of livestock were available for 1883 and 1892. By using Tier 1 and Tier 2 approaches
we found that oxen and bulls had the greatest emission factors, followed by dairy cows and young cattle. The annual
emissions from livestock amounted to 898 kt in 1883and 1061 kt in 1892. Thus, the 2030-emissiontarget
is set 45 kt below the emission level of 1883, and livestock in Germany has been emitting comparable amounts or less
since 2003 relative to 1892. Animal performance increased, and while CH
emission intensities for meat
and milk production decreased from 1883 to 1892,these values were higher thanvalues from 1991 to 2020. Although
the human population ofGermany's currentterritory more thandoubled in the last 130years, increased gain in animal
performance allowed for the reduction in the numbers of ruminants at least during the last 35 years, resulting in
emissions. Such a strategy may also be applied by other countries with steadily increasing human pop-
ulations to balance CH
emissions and food production from livestock.
Science of the Total Environment 848 (2022) 157754
E-mail address: firstname.lastname@example.org (B. Kuhla).
Received 7 April 2022; Received in revised form 14 June 2022; Accepted 28 July 2022
Available online 1 August 2022
0048-9697/© 2022 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC license (http://creativecommons.org/licenses/by-nc/4.0/).
Contents lists available at ScienceDirect
Science of the Total Environment
journal homepage: www.elsevier.com/locate/scitotenv
In its latest Assessment Report, the Intergovernmental Panel on Climate
Change shows that the average temperature of the Earth's atmosphere and
oceans increased by about 1.1 °C from 1850 to 2020 (IPCC, 2021). The rise
in temperature is undoubtedly due to anthropogenic activities associated
with increasing industrialization and accompanying emissions of greenhouse
gases. After carbon dioxide, methane (CH
) emissions make the second larg-
est contribution to global warming. Over the ﬁrst 20 years after release, CH
has 84-times more warming potential than CO
(IPCC, 2006). Its concentra-
tion in the atmosphere has dramatically increased since 1800 with the
highest growth rates between 1945 and 1990 (Etheridge et al., 1998).
Nowadays, roughly 42 % of the global CH
emissions are of non-
anthropogenic origin such as wetlands, oceans, lakes, and rivers whereas
the majority is emitted from anthropogenic sources, namely from activities
in the industrial (29 %) and agricultural (29 %)sectors (Knapp et al., 2014).
Two-thirds of the agricultural CH
emissions are released from enteric
fermentation processes of livestock, which amounts to 17 % of total CH
emissions in the beginning of the 21st century (Knapp et al., 2014). Global
emissions from livestock production have increased steadily at least
since the United Nations Food and Agriculture Organization (FAO) began
collecting statistics. While in 1961 the amount of CH
from enteric fermentation was 65.3 Mt, this had increased by 54 % to
100.8 Mt in 2019 (FAO, 2021). However, the emission rates in the individ-
ual regions of the world show quite different trends. While enteric CH
emissions are continuously increasing in Asia, Africa, and South America
since the early 1960s, they have been decreasing in Oceania and North
America since the mid-1970s and in Europe since the mid-1980s. At the
United Nations (UN) climate conference in Paris 2015, 180 countries
agreed to further reduce greenhouse gas emissions to meet the “below
2 °C target”by the end of the 21st century.
In Germany, enteric CH
emissions declined from 1773 kt in 1985 to
964 kt in 2019 (FAO, 2021). Germany's national inventory reportsa decline
in enteric CH
emissions from 1313 kt in 1990 to 927 kt in 2020 (UBA,
2022). However, this decline was achieved, among other measures, pre-
dominantly by the reduction of farm animal numbers. For example, the
number of pigs, cattle, and sheep decreased from 36.8, 21.5, and 3.8 Mio
in 1985 to 26.1, 11.3, and 1.5 Mio in 2020, respectively (FAO, 2021).
The reduction in animal numbers without compromising food security in
the last 30 years was achieved due to increasing animal performance. For
example, from 1990 to 2020, milk production in Germany increased by
28 %, from 23.672 kt to 33.155 kt, and meat production by 15 %, from
7.194 kt to 8.291 kt, whereas the numbers of cattle, sheep, and pigs
decreased (Statista, 2021). This productivity gain was observed not only
in Germany, but also in other European countries (Gerber et al., 2011;
Dalgaard et al., 2011;O'Brien et al., 2015), and has been identiﬁed as a
major factor reducing CH
emission intensity, which is the ratio between
the amount of CH
produced per unit of animal-derived food (e.g. milk
Germany pursues the aim of achieving greenhouse gas neutrality by
2045. To reach this aim, the emissions from all sectors shall be reduced
by 65 % by 2030 relative to 1990 (UBA, 2022). This means that the enteric
emission rate of livestock must be reduced to an annual emission rate of
853 kt CH
by 2030. The question here arises if this target emission rate
would reach the level of the pre-agroindustrial era, meaning the time
when agricultural activities contributed to the just started increase in
concentration. To answer this question, data about CH
emissions and animal productivities during the 19th century are required.
Thus, the aim of the present study was to collate historical data about live-
stock in Germany, and, based on these, to calculate enteric CH
factors of livestock and Germany's CH
emissions rate and intensity for
the end of the 19th century.
Knowledge about historical CH
emission factors may help developing
countries to more precisely estimate and inventory their past and current
emissions. For Germany, data about historical CH
emission rates and
intensities could serve to adjust the previously deﬁned 2030-mitigation
target,highlight the importance of further efforts needed to continuously re-
duce enteric CH
emission rates, or direct priority to mitigate greenhouse
gas emissions released from sources other than livestock.
2. Materials and methods
First comprehensive counts of livestock species in Germany were con-
ducted in 1873 and thereafter. The livestock numbers in constituent states
of the German Empire without colonies (4 kingdoms, 6 grand duchies,
5 duchies, 7 principalities, and 3 Free and Hanseatic cities), counted on
10th January 1873, 13th January 1883, and on 1st December 1892, were
listed by the “Imperial Statistical Ofﬁce”(Kaiserliches Statistisches Amt,
1874, 1884, 1894). Animal numbers for each of the years were calculated
for Germany's current territory to allow comparability with data gathered
in the 20th and 21st century. To this end, data from East-Prussia, West-
Prussia, Posen, and the imperial territory Alsace-Lorraine were excluded
for analysis. Furthermore, animal numbers of the historic provinces
Brandenburg, Pomerania, Silesia, and Schleswig-Holstein were multiplied
by 0.775, 0.603, 0.056 and 0.825, respectively, thereby accounting for
the area portion of these provinces in Germany's current territory, which
was for Brandenburg: 29,654 km
= 0.775; Pomerania:
= 0.603, Silesia: 2266 km
0.056, and Schleswig-Holstein: 15,682 km
= 0.825. Thus,
animal numbers from 37 subareas of the German Empire were available.
Because data for feed intake, energy intake, energy requirements or
milk constituents of farm animals were not available for the 19th century,
emissions from enteric fermentation was calculated ﬁrst by the Tier
1 approach using the default enteric fermentation CH
(EF) published in Tables 10.10 and 10.11 by IPCC (2006). The default EF
for developing countries were used, which are valid for mules and asses
with a body weight (BW) of 245 kg (EF = 10 kg CH
/year), goats with a
BW of 40 kg (EF = 5 kg CH
/year), sheep with a BW of 45 kg (EF =
/year), horses with a BW of 550 kg (EF = 18 kg CH
(EF = 1 kg CH
/year), bulls and young cattle (EF = 58 kg CH
and dairy cows with an annual milk yield of 2.550 kg (EF = 99 kg CH
year) as in some Eastern European countries.
emissions from enteric fermentation of cattle, horses,
pigs, and sheep subcategories were estimated based on a simpliﬁed Tier 2
approach as suggested by IPCC (2006). To this end, animal numbers and
corresponding BW data for calves (<6 weeks old), calves (between 6
weeks and 6 months old), young cattle (between 6 months and 2 years
old), cows and heifers (>2 years old), oxen and bulls (>2 years old), and
pigs (>1 year old) were obtained from the Imperial Statistical Ofﬁce
(Kaiserliches Statistisches Amt, 1884, 1894). Furthermore, data about the
number of horses (>3 years old), foals (<3 years old), and sheep (<1year
old and >1 year old), but no corresponding BW data, were available
(Kaiserliches Statistisches Amt, 1884, 1894). Data regarding the BW of
horses, foals, and pigs (<1 year old) were available for Prussian districts
(Graf Fink von Finckenstein, 1960); the mean BW of the species were calcu-
lated for the districts Brandenburg, Saxony, Westfalia, and Rhineland and
applied to all German areas. Data for the mean BW of sheep between 5
and 6 months, 6 to 8 months, 8 to 11 months, and >1 year old were ob-
tained from Heinrich (1896) and Conradi (1897).
Based on the BW, dry matter intake(DMI) of cattle was calculated using
the simpliﬁed Tier 2 method as recommended by IPCC (2006).Brieﬂy, DMI
of oxen and bulls was computed according to Eq. 10.18a of IPCC (2006):
DMI ¼BW0:75 0:0119 NEma
is the net energy content of the dietto meet the energy require-
ments for maintenance, accretion of body mass (e.g. fat), and physical
work. The NE
content of the ration was assumed to be 6.8 MJ/kg DM,
which typically consists of moderate forage quality (Table 10.8 in IPCC,
2006) and concentrate to meet the requirements for medium-intensive
physical work (Heinrich, 1896).
B. Kuhla, G. Viereck Science of the Total Environment 848 (2022) 157754
The DMI of young cattle and calves was calculated according to
Eq. 10.17 of IPCC (2006):
DMI kgðÞ¼BW0:75 0:2444 NEma–0:0111 NEma
assuming a NE
content of the ration of 5.5 MJ/kg DM. This value repre-
sents moderate forage quality (Table 10.8 in IPCC, 2006).
The DMI of dairy cows was calculated according to Eq. 10.18b of IPCC
assuming a feed digestible energy (DE) of 60 %. The DE value corresponds
to the weighted mean when ruminants are kept on pasture during the sum-
mer and fed medium quality hay, beets, potatoes, and some concentrate
during winter (Table 10.2 in IPCC, 2006;Heinrich, 1896;Conradi, 1897;
Methane production per head and day of calves (between 6 weeks and
6 months old), young cattle, oxen and bulls, and dairy cows was also calcu-
lated based on estimated DMI and BW according to Jentsch et al. (2007):
CH4kJ kg DM 1head1day 1
considering a CH
energy content of 39.57 kJ/L and a density of 0.700 kg/
(at 1 bar and 7.5 °C, which was the average annual temperature in the
last two decades of the 19th century). The equation by Jentsch et al.
(2007) was used as it has been derived from 337 observations during
studies performed in Germany inmid-20th century, and because the EF pro-
posed by Dämmgen et al. (2012) is only valid for German cows producing
4700 to 7200 kg milk per year. Methane production of calves <6 weeks
old was calculated based on the data published by Tümmler et al. (2020),
with calves that had nearly ad libitum milk intake and a daily plant dry
matter intake of 100 g, which amounts to 1 kg CH
per head and year.
emissions from calves with an age of <6 weeks were calculated
according to the Tier 1 method.
Similarly, as the CH
emission factors proposed by IPCC (2006) for
horses, swine, and sheep are only reliable for the given BW, CH
per head and day for horses, pigs, and sheep was calculated according to the
equations by Franz et al. (2010):
for horses :CH4Lhead1day1
for pigs :CH4Lhead1day 1
and for sheep :CH4Lhead1day 1
In addition, because BW data for goats and mules and asses were not
available, enteric CH
production of these species was calculated by the
Tier 1 approach only. Annual CH
emission was calculated by multiplying
the number of animals of each area by the daily CH
by 365. A normal distribution of animal numbers throughout the year
and within areas was assumed.
The calculation of CH
emission intensity was performed using milk
yield data published by Graf Fink von Finckenstein (1960) and Helling
(1965) for the late 19th century. Therein, the average milk production of
dairy cows in the Prussian districts of Brandenburg, Saxony, Westfalia,
and Rhineland was 1825 kg in 1883 and 2125 kg in 1892, and milk yield
in Bavaria was estimated as 2400 L/year during the last years of the 19th
century. Data about the production of beef and veal (426 kt in 1883,
562 kt in 1892), pork (567 kt in 1883, 736 kt in 1892), and sheep and
goat meat (85 kt in 1883, 86 kt in 1892) were calculated based on the
average consumption per person in the kingdoms Prussia and Saxony
(Esslen, 1912) and the number of persons who lived in Germany's current
territory (Kaiserliches Statistisches Amt, 1884, 1894).
In order to allow the comparison between historical and current emis-
sion levels, data about enteric CH
production in Germany in the 21st
century were obtained from UBA (2022),FAO (2021),andVos et al.
(2022). Milk production and meat production data since 1991 were
obtained from Statista (2021) and the German Ministry for Nutrition and
Agriculture (BMEL, 2021), respectively.
The mean and standard deviation (SD) was calculated, when appropri-
ate, for the 37 areas of the German Empire belonging to Germany's current
territory. Otherwise, no further statistical analysis was performed but data
were interpreted by descriptive statistics.
The number of horses, cows, pigs, and goats continuously increased
from 1873 to 1893 whereas the number of mules and asses, other cattle,
and sheep decreased (Table 1). Using the Tier 1 approach, CH
from enteric fermentation of all livestock categories amounted to 1085,
1087, and 1133 kt CH
in 1873, 1883, and 1892, respectively. These
numbers, however, are only rough estimates; therefore, we next applied a
simpliﬁed Tier 2 model using BW data of livestock subcategories available
for 1883 and 1892.
From 1883 to 1892, BW of all livestock subcategories increased, and so
did DMI of dairy cows and other cattle (Table 2). Furthermore, the EF, ex-
cept for both pig subcategories and sheep older than 1 year, were lower
than the default-EF proposed for the Tier 1 approach (Table 3). Accord-
ingly, enteric CH
emissions from all livestock categories were lower than
the emissions calculated based on the Tier 1 approach only. Enteric CH
emissions from livestock increased from 898 kt in 1883 to 1060 kt in
1892 (Table 3) and were greatest in the four kingdoms and lowest in the
Hanseatic town Lübeck (Supplemental Table 1).
emission rate continuously decreased during the last 35
years (Fig. 1). Nonetheless, the 1892-level is higher than the annual enteric
emission rate published by the Federal Environmental Ofﬁce (UBA,
2022) for 2003 and thereafter, as well as higher than the emission rate pub-
lished by FAOSTAT (FAO, 2021) for 2009 and thereafter. However, the two
emission levels in the late 19th century are above Germany's 2030-target
emission rate of 853 kt CH
per year (e.g., 65 % reduction relative to the
1990 emission level (UBA, 2022)).
While enteric CH
emissions increased from 1883 to 1892, agricultural
productivity did alike (see Materials and methods section). Accordingly,
emission intensities, except for pork, decreased in the same time and
further declined until 1991; however, CH
emission intensities for beef
and veal have been re-increasing since 1991 (Fig. 2A and B). As expected,
emission intensities are greater for beef, veal, and sheep and goat
Number of animals and Tier 1 enteric CH
emissions from livestock categories
adjusted for Germany's current territory.
Animal category Number of animals (thousands)
(kt × year
1873 1883 1892 1873 1883 1892
Horses 2063 2170 2373 37.1 39.1 42.7
Mules and asses 9.32 6.17 3.65 0.09 0.06 0.04
Pigs 5219 6593 9025 5.22 6.59 9.02
Cows 6689 6733 7343 662 667 727
Other cattle 5130 5258 5116 298 305 297
Sheep 14,603 11,714 8929 73.0 58.6 44.6
Goats 1948 2236 2529 9.7 11.2 12.6
Total 1085 1087 1133
Animal numbers for the German Empire (Kaiserliches Statistisches Amt, 1874,
1884, 1894) were curated for Germany's current territory not including the
Eastern territories (now belonging to Poland and Russia), the imperial territory
Alsace-Lorraine (now belonging to France), and Northern Schleswig (now belong-
ing to Denmark); and the area portions of Brandenburg, Pomerania, Silesia, and
B. Kuhla, G. Viereck Science of the Total Environment 848 (2022) 157754
meat, and are lower for pork and milk production, independent of the years.
Interestingly, enteric CH
emission intensityfor beef and veal production in
1991 was lower than it was for sheep and goat meat production in 1883
The production level of animal-derived food is closely associated with
the number of citizens of each country. Therefore, we next calculated the
annual enteric CH
-footprint per person. Despite increased animal perfor-
mance, the CH
-footprint per person in Germany's current territory slightly
increased from 1883 to 1892, whereas it decreased by 59 % until 2020
4.1. Emission factors
Applying the Tier 1 approach for developing countries (IPCC, 2006)to
Germany's livestock population of the 19th century revealed that the
Number and body weight of livestock subcategories as well as dry matter intake of cattle after normalization to Germany's current territory.
Animal subcategory Number of animals
Body weight (kg)
Dry matter intake (kg × day
1883 1892 1883 1892 1883 1892
>3 years old 1834 2089 440 ± 64 486 ± 102
Foals <3 years old 336.5 284.4 190 ± 12 201 ± 17
>1 year old 1469 2078 122 ± 24 125 ± 18
<1 year old 5098 6947 71 76 ± 16
>2 years old (oxen and bulls) 1151 1150 474 ± 62 516 ± 59 11.1 ± 1.1 11.6 ± 2.1
>2 years old (dairy) 6733 7343 390 ± 57 421 ± 54 10.5 ± 1.5 11.1 ± 2.2
<2 years old (all) 2361 3005 204 ± 29 229 ± 40 5.3 ± 0.6 5.6 ± 1.2
>6 weeks to <6 months old 873.3 961.4 93 ± 11 101 ± 15 2.9 ± 0.3 3.1 ± 0.3
<6 weeks old 532.4 416.0 51 ± 7 55 ± 6 0.1 0.1
>1 year old 8969 6419 43 43
<1 year old 2745 2529 28 28
Animalnumbers and body weight of animalsof the German Empire(Kaiserliches Statistisc hes Amt, 1884, 1894) were curatedfor Germany's current territory not including
the Eastern territories (now belonging to Poland and Russia), the imperial territory Alsace-Lorraine (now belonging to France), and Northern Schleswig (now belonging to
Denmark); and the area portions of Brandenburg, Pomerania, Silesia, and Schleswig-Holstein.
Data are given asmean ± SD; SD refers to the deviation of body weightand dry matter intake of animals kept in the 37 areas of the German Empire (see Supplementary
Table 1) belonging to Germany's current territory.
Dry matter intake (DMI) for oxen and bulls: DMI = BW
+ 0.1938)/NE, with net energy content of the ration (NE) = 6.8 MJ/kg DM; for young
cattle and calves: DMI = BW
× (0.2444 × NE −0.0111 × NE
−0.472)/NE, with NE = 5.5 MJ/kg DM; for dairycows: DMI = (5.4 × BW/500)/((100 −DE%)/100),
with digestible energy (DE) = 60 % (IPCC, 2006).
emission factors and total enteric CH
emissions from livestock subcat-
egories in 1883 and 1892.
Animal subcategory Enteric CH
(kg × head
(kt × year
1883 1892 1883 1892
>3 years old
16.9 18.6 30.9 38.8
Foals <3 years old
7.5 7.9 2.5 2.2
Mules and asses
10.0 10.0 0.06 0.04
>1 year old
2.1 ± 0.4 2.1 ± 0.3 3.0 4.6
<1 year old
1.2 1.3 6.2 9.1
>2 years old (oxen and bulls)
93.7 ± 10.3 100.2 ± 9.5 104.6 112.4
>2 years old (dairy)
83.8 ± 12.3 89.8 ± 10.1 550.2 667.6
<2 years old (all)
42.6 ± 5.1 46.9 ± 7.0 99.8 138.4
>6 weeks to <6 months old
21.5 ± 2.2 22.9 ± 2 18.9 22.0
<6 weeks old
1.0 1.0 0.5 0.2
>1 year old
6.5 6.5 58.1 41.6
<1 year old
4.3 4.3 11.7 10.7
5 5 11.2 12.6
Total 897.6 1060.3
SD refers to the deviation of enteric CH
emission factors between 37 areas of
the German Empire (Supplementary Table 1) belonging to Germany's current
emissions calculated based on body weights (simpliﬁed Tier 2 model) for
(L × head
) = 0.18 × BW
; for pigs: CH
(L × head
) = 0.07 × BW
(L × head
) = 0.66 × BW
(Franz et al.,2010); for oxen and bulls, dairy cows, young cattle, and calves between
(kJ × kg DM
1802–21.1 × DMI/BW (g/kg) (Jentsch et al., 2007).
Calculated according to IPCC Tier 1 model using the standard emission factors
for mules and asses (10 kg CH
/year), goats (5 kg CH
/year) (IPCC, 2006), and
calves <6 weeks (1 kg CH
/year; Tümmler et al., 2020).
Fig. 1. Enteric CH
emissions in Germany between 1961 and 2019 based on
FAOSTAT statistics (2021) (solid line) and between 1990 and 2021 based on
Germany's Federal Environmental Ofﬁce (UBA, 2022) (dotted line). The horizontal
grey lines indicate the emission level in 1883 and 1892, respectively. Emissions
were calculated according to either the simpliﬁed Tier 2 approach for horses,
dairy cows, oxen and bulls, young cattle and calves (6 weeks to 6 months old),
pigs, and sheep, or the Tier 1 model for mules and asses, goats, and calves <6
B. Kuhla, G. Viereck Science of the Total Environment 848 (2022) 157754
emissions amounted to an average of 1123 kt between 1873
and 1892. Although this number was corrected for those parts of the coun-
try not belonging to Germany's current territory, it still underlies some un-
certainties. For example, the EF for horses provided by IPCC (2006)
assumes an average BW of 550 kg, but the mean BW of adult horses (>3
years old) in the last two decades of the 19th century ranged only between
440 and 486 kg. Thus, the default EF of 18kg/year is apparently slightly too
high to be meaningfully used for horses kept in the 19th century. On the
other hand, horses were intensively used as draft-animals, suggesting that
they consumed more feed per kg BW than in the late 20th and early 21st
century. The calculated EF of 16.9 kg CH
for the year 1883 and 18.6 kg
for the year 1892 therefore seem justiﬁed.
Furthermore, the default EF for sheep with a mean BW of 45 kgis 5 kg/
year, but the BW of sheep greater than a 1 year old was only 43 kg in the
late 19th century, suggesting again an overstatement of CH
with the Tier 1 approach. However, taking the feeding experiments
(Klemme, 2003) and feeding recommendations for sheep at the end of
the 19th century into account (Heinrich, 1896), in which not just pasture
and hay, but also concentrate feeding, particularly for lactating animals,
is recommended, a higher EF of 6.5 kg/year for a 43 kg-sheep is reasonable.
This EF may underestimate real CH
emissions because Pelchen and Peters
(1998) reported enteric emissions of 20.6 g CH
/d or 7.5 kg CH
/year for a
growing 40 kg sheep. However, both of these factors are lower than the de-
fault EF for sheep with a BW of 65 kg in developed countries (EF = 8 kg
/year) (IPCC, 2006).
The IPCC (2006) proposes a Tier 1 EF for pigs of 1 kg/year for develop-
ing countries and 1.5 kg/year for developed countries. In the current
German emission inventory an EF of 1.15 kg/year for pigs is applied
(Haenel et al., 2020). However, BW gain of fattening pigs steadily increased
in the 20th and 21st century (Haenel et al., 2020), although daily feed in-
take of fattening pigs is comparable between the late 19th and early 21st
century (Conradi, 1897;Heinze, 2011). Consequently, the amount of feed
consumed during the time of birth until slaughter, and thus CH
is much lower today than it was in the 19th century. In addition, in the 19th
compared to the 21st century, pigs were fed higher portions of roughage
feed, and thus crude ﬁbre, and sows were not restrictively fed in late gesta-
tion (Heinrich, 1896;Conradi, 1897); both factors increasing annual CH
emissions. Finally, BW at slaughter did not change from 1900 to 2021
(Statista, 2021), and thus the EF for pigs in the 19th century must have
been higher than they are today. Accordingly, the EF calculated based on
our simpliﬁed Tier 2 approach (1.2 to 2.1) seems to be reasonable.As a con-
sequence, the Tier 1 model underestimates annual CH
emissions from pigs
by 2.6 kt for 1883 and 4.4 kt for 1892 relative to the Tier 2 model.
emissions from mules and asses andgoats could only be
estimated using the default Tier 1 EF (IPCC, 2006) because of lack of histor-
ical data referring to BW, number of foals, or goat kids. Such data are still
rare today, and subsequently the German national emission inventory
uses a constant EF of 5 kg/year for goats and summarises the emissions
from mules and asses into the “horse”category (Haenel et al., 2020). Al-
though the latter approach certainly overestimates CH
mules and asses, and although today's emissions from this animal category
is much lower than in the 19th century, they do not contribute much to the
emission from livestock.
By contrast, in 1883 and 1892 the cattle category contributed to the
total enteric CH
emissions by 89 % to 90 % (Tier 1 model), or 85 % to
88 % (Tier 2 model). Multiple data sources are required to conﬁrm and se-
cure these emission estimates. While the number of animals in each cattle
Fig. 2. Methane emission intensities for beef and veal, sheep and goat meat (A),
pork and milk production (B), and methane emission per person (C) in Germany's
current territory in 1883 and 1892 as compared to 1991 until 2020. Emissions in-
tensities in the 19th century were calculated based on the numbers presented in
Table 3, and milk and meat production data published by Hoffmann (1965).
Emissions intensities between 1991 and 2020 were calculated based enteric CH
emissions published by Vos et al. (2022), milk and meat production by Statista
(2021) and BMEL (2021).
B. Kuhla, G. Viereck Science of the Total Environment 848 (2022) 157754
subcategory and their BW were available in high special resolution, the
actual DMI was not and had to be estimated based on BW. Oxen and bulls
ingested 11.1 kg DM/d at a BW of 474 kg and ingested 11.6 kg DM/d at
a BW of 516 kg. These data are not comparable to the DMI of modern
500 kg Simmental bulls consuming only 8.7 to 9.5 kg DM/d while reaching
an average daily gain of 1200 g (Gruber, 2014). One might assume that the
daily BW gain of male cattle in the 19th century was lower than 1.2 kg/day,
and thus, DMI per unit of BW would also be lower. However, in the 19th
century, oxen and bulls were intensively used as draft animals. For
middle-hard working animals, the daily organic matter (OM) intake
amounted to 24 kg, for heavily working animals to 26 kg OM, and for ani-
mals kept in tie-stalls to 17.5 kg OM per 1000 kg BW (Conradi, 1897). The
average of these calculates to 11.2 kg OM intake per day/500 kg BW. Con-
sidering that the OM intake misses the portion of mineral intake (and also
soil intake when on pasture), which is approx. 10 % of DMI, oxen and
bulls must have consumed rather 12.3 kg DM/d in the late 19th century.
Hence, the DMI of oxen and bulls calculated by the simpliﬁed Tier 2 ap-
proach is not overestimated. This conclusion is further supported by IPCC
(2006) reporting that the average enteric CH
emissions from “other cat-
tle”, e.g. bulls, growing steers, heifers, and calves, amounts to 58 kg/year
in Eastern European countries and to 57 kg/year in Western European
countries, and that the emissions from male cattle older than 2 years old
are much greater than from growing cattle and calves.
The average daily OM intake of 2 to 3 months old calves with a BW
of 75 kg was given as 1.65 kg/d, for 3 to 6 months old calves (BW =
150 kg) as 3.5 kg/d, and for young cattle (6 to 12 months old, BW =
250 kg) as 6 kg/d (Conradi, 1897). Having in mind again that the OM
intake does not include mineral intake, these data correspond well to the
calculated DMI of calves and young cattle based on the assumed average di-
etary net energy content (5.5 MJ/kg DM) and the IPCC (2006) equation.
Considering the CH
emissions from oxen and bulls, it seems that the
error of the estimated CH
emissions for the 19th century increases with in-
creasing BW of cattle. However, the average EF for oxen and bulls, young
cattle, and calves (6 weeks to 6 months old) calculates to 53 kg CH
1883 and 57 kg CH
in 1882, but these numbers are comparable with the
default EF for the category “other cattle”in Eastern and Western Europe
Methane emissions from calves on milk, e.g. <6weeksold,canhardly
be assessed not at least because IPCC (2006) assumes a digestibility of
feed of 0 % for this subcategory. However, based on the given BW, the
emission from calves younger than 6 weeks old was estimated
according to the experimental data published in Tümmler et al. (2020).
Therein, the average daily DMI of solid feed of calves from birth until 6
weeks of life amounts to 0.1 kg, and daily CH
production of 6 weeks old
calves to 8–12 L/d. Based on these numbers an EF of 1 kg per calf (<6
weeks old) and year was deduced, but their contribution hardly affects
emissions from livestock.
By contrast, CH
emissions from dairy cows contributed most to total
emissions and small estimation errors have a tremendous impact on total
emissions. The default Tier 1 EF of dairy cows in Eastern Europe is 99 kg/
year while an average annual milk production of 2550 kg is assumed
(IPCC, 2006). Conversely, milk yield of dairy cows in the Prussian districts
of Brandenburg, Saxony, Westfalia, and Rhineland (Graf Fink von
Finckenstein, 1960) and in the Bavarian kingdom was much lower than
2550 kg per year in the late 19th century (Helling, 1965), suggesting that
the Tier 1 EF of 99 kg/year clearly overestimates real emissions. Following
our simpliﬁed Tier 2 approach, the EF fordairy cows was 84 kg in 1883 and
90 kg in 1892, which were lower than the default value from IPCC (2006),
but comparable to current EF for dairy cows in South Africa ranging
between 77 and 92 kg CH
/year (Tongwane and Moeletsi, 2020).
However, besides the level of milkproduction, BW and OM digestibility
are the primary factors determining DMI. In the present study, we assumed
an average of 60 % OM digestibility considering the reported feed stuff fed
in the 19th century (Klemme, 2003) and corresponding digestibilities rang-
ingbetween46and75%(Conradi, 1897;Heinrich, 1896). It has been re-
ported that dairy cows would consume 9.6 kg OM/400 kg BW in the late
19th century, but it remained unclear at which production level this intake
was achieved (Conradi, 1897). Assuming a dietary mineral content of 10 %
of DM, the 9.6 kg OM equals to 10.5 kg DM, which agrees to the DMI of
dairy cows calculated for 1883 and 1892. Moreover, extrapolating the
14.5 kg DMI of a 500 kg-dairy cow producing 4000 kg milk/year (Gruber
et al., 2001) to a 400 kg-dairy cow producing 2000 kg milk/year, results
in a DMI of 10.5 kg. Based on these numbers, we conclude that the use of
an EF of 84 kg in 1883 and 90 kg in 1892 for dairy cows seems to be appro-
priate. In addition, the EF for cattle were calculated using the equation by
Jentsch et al. (2007) and the appropriateness of this equation has been ap-
proved by Piatkowski et al. (2010), who predicted enteric CH
from German cattle to amount to 1036 kt in 2006, which corresponds
well to the FAO value of 1042 kt CH
that was emitted from whole German
livestock in the same year (FAOSTAT, 2021).
4.2. Total enteric CH
The enteric CH
emission level from Germany's livestock was proposed
to be >1500 kt in 1890 (Muylaert de Araujo et al., 2007), however, this
number is highly overstated, likely because animal numbers were not
corrected for the territory b oundaries and because inadequate default emis-
sion factors were used. After 1890 and until the mid-80s of the 20th cen-
tury, livestock numbers in Germany have steadily increased and their
contribution to the atmospheric CH
load was assumed to be 2.9 % of the
global enteric CH
emissions (Muylaert de Araujo et al., 2007). Due to the
reasons mentioned above this number is deﬁnitely overestimated. Our
calculations provide also evidence to the prediction of historic methane
emissions using an extrapolation modelling approach (Gütschow et al.,
2016), the latter estimating CH
emissions from the agricultural sector to
amount to 0.98 Mt in 1883 and 1.07 Mt in 1892.
In the 21st century, the enteric CH
emission rate in Germany (UBA,
2022) reached or felt below the 1892-value for the ﬁrst time since 2003.
However, the 2030-target emission rate of 853 kt CH
per year is below
the 1883-emission level. Thus, it remains to be examined in future studies
when in the 19th or 18th century the enteric CH
emission rate was equal
or lower than 853 kt. Hence, <10 % of the 1990 enteric CH
level remain to be reduced to meet the 2030-target rate. Although further
effort is needed to reach this aim (see suggestions below), focussing only
on the reduction of enteric CH
emissions may overlook the fundamental
importance of reducing CO
emissions as quickly as possible, because CO
emissions from oil and natural gas systems have been underestimated in
the past (Rutherford et al., 2021).
Historical studies have shown that global enteric CH
to increase by at least 1860 (Stern and Kaufmann, 1996). In France, CH
emission from livestock were lower in 1852 than 1885 (Garnier et al.,
2019), suggesting that the increase in CH
emissions from livestock had al-
ready started in the middle of the 19th century or even earlier.
4.3. Productivity and enteric CH
Germany's current CH
emission rate can further be reduced, particu-
larly in view of its self-sufﬁciency rate in milk, pork, and cheese production
amounting to 112 %, 120 %, and 121 %, respectively (Statista, 2021). Con-
sidering the emissions from individual livestock species in 2020 (Vos et al.,
2022), a further 20 % reduction in pig numbers would save 5 kt, and a
further 12 % reduction in dairy cow numbers would save 66 kt enteric
per year without jeopardizing self-sufﬁciency or nutritional practices
related to milk and pig product consumption while falling below the
national 2030-target level. It is noteworthy that the German Empire had a
butter export surplus of 6.4 and 9.8 % in 1874 and 1884, respectively,
(Teuteberg, 1988), demonstrating that overproduction of some milk prod-
ucts had already begun in the late 19th century. At least some portion of
this overproduction was achieved by grain imports, mainly from Russia
(Mahlerwein, 2016). On the other hand, the German Empire imported
more beef than it had exported in the late 19th century (Lohheide, 2008).
Nowadays, Germany's self-sufﬁciency rate in beef production is only 97 %
B. Kuhla, G. Viereck Science of the Total Environment 848 (2022) 157754
(Statista, 2021), and as such,Germany, like many other EU27countries, im-
ports food with one of the highest carbon footprints (Bellarby et al., 2013).
Many studies have shownthat a reduction in beefconsumption linked with
reduced global production is the most effective CH
(Popp et al., 2010;Bellarby et al., 2013;Shaﬁullah et al., 2021). The annual
meat consumption in Germany ranged between 55 and 62 kg per person be-
tween 2000 and 2020 (Statista, 2021), whereas it was only 33 kg and 38 kg
in 1883 and 1892, respectively (Hoffmann, 1965). These data underline
that Germany's further CH
mitigation potential lies in reducing beef con-
sumption to further reduce beef import, and that the resulting protein gap
could be closed by consuming milk products possessing a lower CH
sion intensity than beef.Dyer et al. (2020) suggested for Canada a reduction
in beef production and instead an expansion of broiler production to satisfy
the required national protein intake; however, the annual consumption of
meat from poultry in Germany has already increased from <2kginthe
19th century to >22 kg per person in 2020 (Hoffmann, 1965;Statista,
2021), and, unlike beef consumption, exacerbates feed-food competition
The human population in Germany's current territor y increased from
34 Mio in 1883 to 83 Mio in 2020. In the same time, consumption of
animal-derived food increased and enteric CH
intensity and emissions
per person decreased, indicating a signiﬁcant improvement in agricul-
tural production efﬁciency. Gerber et al. (2011),forexample,demon-
cow leads to an overall CO
-equivalents reduction by a factor of four.
The improvement in animal efﬁciency and the parallel reduction in an-
imal numbers may be an example for reversing increasing enteric CH
emissions in developing countries with a steadily increasing human
population, such as in Asia and Africa. Such a strategy may balance
climate impacts and food security.
By using Tier 1 and Tier 2 approaches we found that oxen and bulls
had the greatest emission factors, followed by dairy cows and young cat-
tle. These emission factors, as far as applicable, can be used by other
countries in case the IPCC or other default factors are not appropriate,
and thus may serve to reﬁne national inventories. Germany's emission
mitigation aims for the 2030-target an emission of 45 kt CH
the area-normalized historic emission level of 1883. Thus, <10 % of
the 1990 enteric CH
emission level remain to be reduced, and further
effort, such as the reduction of dairy cow numbers, is needed to reach
thetargetratesothatinthelong-term,the“below 2 °C target”adopted
in Paris in 2015 can still be achieved.
Given that the production of some milk products exceeded Germany's
self-sufﬁcient rate already in the late 19th century, the highest CH
tion potential lies in the further reduction of milk production by decreasing
dairy cow numbers and lowering the utilisation of edible biomass. How-
ever, relative to the national inventory, Germany has been emitting equal
or less enteric CH
since 2003 compared to 1892 and thereafter despite
a near doubling of the human population from the late 19th to the
early 21st century. The combination of the increase in animal performance
and reduction of animal numbers secured the food supply and reduced
emission intensity and total CH
emissions in the last three
decades. This strategy should be continued, and could also be applied by
developing countries to balance national CH
emissions from livestock
Supplementary data to this article can be found online at https://doi.
CRediT authorship contribution statement
G.V. developed the idea and provided historical data. B.K. performed
the calculations and wrote the manuscript. Both authors contributed
to the interpretation of the results and approved the ﬁnal version of the
Declaration of competing interest
The authors declare that they have no known competing ﬁnancial inter-
ests or personal relationships that could have appeared to inﬂuence the
work reported in this paper.
The authors thank Rebecca Eichhorn, Research Institute for Farm
Animal Biology (FBN) for her help in literature search and Katherine M.
Kennedy for language editing. The publication received ﬁnancial support
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