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.

In its climate protection law, Germany pursues the aim of achieving greenhouse gas neutrality by 2045. To approach this aim, the emissions from all sectors 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 by 2030, but if this target rate reaches the level of the pre-agroindustrial era remains to be evaluated. The present study aimed to determine enteric CH emission factors, emission rates and intensities for Germany 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 enteric CH emissions from livestock amounted to 898 kt in 1883 and 1061 kt in 1892. Thus, the 2030-emission target is set 45 kt below the emission level of 1883, and livestock in Germany has been emitting comparable amounts or less enteric CH 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 than values from 1991 to 2020. Although the human population of Germany's current territory more than doubled in the last 130 years, increased gain in animal performance allowed for the reduction in the numbers of ruminants at least during the last 35 years, resulting in declining CH emissions. Such a strategy may also be applied by other countries with steadily increasing human populations to balance CH emissions and food production from livestock.