A 130-year global inventory of methane emissions from livestock: trends, patterns, and drivers

Livestock contributes approximately one-third of global anthropogenic
methane (CH4) emissions. Quantifying the spatial and temporal variations
of these emissions is crucial for climate change mitigation. Although
country-level information is reported regularly through national
inventories and global databases, spatially-explicit quantification of
century-long dynamics of CH4 emissions from livestock has been poorly
investigated. Using the Tier 2 method adopted from the 2019 Refinement to
2006 IPCC guidelines, we estimated CH4 emissions from global livestock at
a spatial resolution of 0.083° (~ 9 km at the equator) during the period
1890−2019. We find that global CH4 emissions from livestock increased from
31.8 [26.5−37.1] (mean [minimum−maximum of 95% confidence interval) Tg CH4
yr-1 in 1890 to 131.7 [109.6−153.7] Tg CH4 yr-1 in 2019, a fourfold
increase in the past 130 years. The growth in global CH4 emissions mostly
occurred after 1950 and was mainly attributed to the cattle sector. Our
estimate shows faster growth in livestock CH4 emissions as compared to the
previous Tier 1 estimates and is ~20% higher than the estimate from
FAOSTAT for the year 2019. Regionally, South Asia, Brazil, North Africa,
China, the United States, Western Europe, and Equatorial Africa shared the
majority of the global emissions in the 2010s. South Asia, tropical
Africa, and Brazil have dominated the growth in global CH4 emissions from
livestock in the recent three decades. Changes in livestock CH4 emissions
were primarily associated with changes in population and national income
and were also affected by the policy, diet shifts, livestock productivity
improvement, and international trade. The new geospatial information on
the magnitude and trends of livestock CH4 emissions identifies emission
hotspots and spatial-temporal patterns, which will help to guide
meaningful CH4 mitigation practices in the livestock sector at both local
and global scales.