International Center for Climate and Global Change Research and School of Forestry and Wildlife Sciences, Auburn University, Auburn, AL, USA.
State Key Laboratory of Urban and Regional Ecology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, China.
Glob Chang Biol. 2017 Oct;23(10):4147-4161. doi: 10.1111/gcb.13709. Epub 2017 May 10.
Human demand for livestock products has increased rapidly during the past few decades largely due to dietary transition and population growth, with significant impact on climate and the environment. The contribution of ruminant livestock to greenhouse gas (GHG) emissions has been investigated extensively at various scales from regional to global, but the long-term trend, regional variation and drivers of methane (CH ) emission remain unclear. In this study, we use Intergovernmental Panel on Climate Change (IPCC) Tier II guidelines to quantify the evolution of CH emissions from ruminant livestock during 1890-2014. We estimate that total CH emissions in 2014 was 97.1 million tonnes (MT) CH or 2.72 Gigatonnes (Gt) CO -eq (1 MT = 10 g, 1 Gt = 10 g) from ruminant livestock, which accounted for 47%-54% of all non-CO GHG emissions from the agricultural sector. Our estimate shows that CH emissions from the ruminant livestock had increased by 332% (73.6 MT CH or 2.06 Gt CO -eq) since the 1890s. Our results further indicate that livestock sector in drylands had 36% higher emission intensity (CH emissions/km ) compared to that in nondrylands in 2014, due to the combined effect of higher rate of increase in livestock population and low feed quality. We also find that the contribution of developing regions (Africa, Asia and Latin America) to the total CH emissions had increased from 51.7% in the 1890s to 72.5% in the 2010s. These changes were driven by increases in livestock numbers (LU units) by up to 121% in developing regions, but decreases in livestock numbers and emission intensity (emission/km ) by up to 47% and 32%, respectively, in developed regions. Our results indicate that future increases in livestock production would likely contribute to higher CH emissions, unless effective strategies to mitigate GHG emissions in livestock system are implemented.
在过去几十年中，人类对牲畜产品的需求迅速增长，主要原因是饮食结构的转变和人口增长，这对气候和环境产生了重大影响。从区域到全球，人们已经广泛研究了反刍动物对温室气体（GHG）排放的贡献，但甲烷（CH ）排放的长期趋势、区域差异和驱动因素仍不清楚。在这项研究中，我们使用政府间气候变化专门委员会（IPCC）二级指南来量化 1890 年至 2014 年期间反刍动物牲畜甲烷排放的演变。我们估计，2014 年，反刍动物牲畜的总 CH 排放量为 9710 万吨 CH 或 27.2 亿吨 CO -eq（1MT=10g，1Gt=10g），占农业部门所有非 CO GHG 排放量的 47%-54%。我们的估计表明，自 19 世纪 90 年代以来，反刍动物牲畜的 CH 排放量增加了 332%（7360 万吨 CH 或 2.06 亿吨 CO -eq）。我们的研究结果还表明，2014 年，干旱地区的畜牧业排放强度（每公里 CH 排放量）比非干旱地区高 36%，这是由于牲畜数量增长率较高和饲料质量较低的综合影响。我们还发现，发展中地区（非洲、亚洲和拉丁美洲）对总 CH 排放量的贡献从 19 世纪 90 年代的 51.7%增加到 2010 年代的 72.5%。这些变化是由发展中地区牲畜数量（LU 单位）增加了 121%，而发达地区牲畜数量和排放强度（每公里排放量）分别减少了 47%和 32%所驱动的。我们的研究结果表明，除非在牲畜系统中实施有效的 GHG 减排战略，否则未来增加牲畜生产可能会导致 CH 排放量增加。
