Department of Sustainable Agricultural Systems, BOKU - University of Natural Resources and Life Sciences, Vienna, Austria.
Department of Sustainable Agricultural Systems, BOKU - University of Natural Resources and Life Sciences, Vienna, Austria.
Animal. 2022 Oct;16(10):100638. doi: 10.1016/j.animal.2022.100638. Epub 2022 Sep 29.
Livestock farming is of major economic relevance but also severely contributes to environmental impacts, especially greenhouse gas (GHG) emissions such as methane (CH; particularly from ruminant production) and nitrous oxide (NO; mainly from manure management and soil cultivated for feed production). In this study, we analyse the impact of GHG emissions from Austrian livestock production, using two metrics: a) the commonly used global warming potential (GWP) over 100 years (GWP in CO-equivalents, CO-e), and b) the recently introduced metric GWP*, which describes additional warming as a function of the timeline of short-lived GHG emissions (unit CO warming equivalents, CO-we). We first compiled the sectoral (i.e. only direct emissions without upstream processes) GWP for different livestock categories with a focus on dairy cattle, beef cattle and pigs in Austria between 1990 and 2019. We also estimated product-related (i.e. per kg carcass weight or per litre of milk) GWP values, including upstream processes. We then calculated the corresponding GWP* metrics, both sectoral and product-related, and compared them with the GWP values. Decreasing livestock numbers and improved production efficiency were found to result in strong sectoral emission reductions from dairy production (-32 % of GWP from 1990 to 2019) and from pigs (-32 % CO-e). This contrasts with low reductions from other livestock categories and even increases for cattle other than dairy cows (+3 % CO-e), mainly due to rising suckler cow numbers. Allocated results per kg milk and kg body mass show quite similar results. Using the GWP* metric, the climate impacts of Austrian livestock production are less severe. When assuming constant management and emission intensity over a period of at least 20 years, the CO-we (GWP*) is almost 50 % less than CO-e (GWP) per kg Austrian raw milk due to the different impacts of the short-lived CH. A similar trend applies to an average cattle carcass (-40 % warming impact). The emission reductions of the shrinking Austrian livestock population represent an important contribution to a climate-neutral agriculture: The CH reductions of livestock production during the past 20 years reduce the current total Austrian CO-we by 16 %. Continuous CH reduction, as we show it here for Austrian livestock, is an effective option to tackle the climate crisis in the short term. It shall be stressed that a relatively low GWP* should not be interpreted as a concession for further CH emissions but as an actual reduction of (additional) warming.
畜牧业具有重要的经济意义，但也对环境影响，尤其是温室气体（GHG）排放造成严重影响，如甲烷（CH；特别是反刍动物生产）和氧化亚氮（NO；主要来自粪便管理和饲料生产用耕地）。在本研究中，我们使用两种指标分析了奥地利畜牧业 GHG 排放的影响：a）常用的 100 年全球变暖潜能值（GWP100）（以 CO2 当量表示的 GWP，CO-e），b）最近引入的指标 GWP*，它描述了短寿命 GHG 排放随时间变化的额外变暖（单位 CO 变暖当量，CO-we）。我们首先编制了 1990 年至 2019 年奥地利不同畜牧业部门（即无上游过程的直接排放）的 GWP，重点是奶牛、肉牛和猪。我们还估计了与产品相关的（即每公斤胴体重量或每升牛奶）GWP 值，包括上游过程。然后，我们计算了相应的 GWP指标，包括部门和产品相关的指标，并将其与 GWP 值进行了比较。我们发现，减少牲畜数量和提高生产效率导致乳制品生产的部门排放量大幅减少（1990 年至 2019 年 GWP 减少 32%），以及猪的排放量减少 32%（CO-e）。这与其他牲畜类别的减排量低甚至奶牛以外的牛的排放量增加（CO-e 增加 3%）形成对比，这主要是由于奶牛数量的增加。按每公斤牛奶和每公斤体重分配的结果显示出相当相似的结果。使用 GWP指标，奥地利畜牧业的气候影响不那么严重。假设在至少 20 年的时间内保持管理和排放强度不变，由于短寿命 CH 的不同影响，每公斤奥地利生奶的 CO-we（GWP*）几乎比 CO-e（GWP）少 50%。对于平均牛胴体，也有类似的趋势（变暖影响减少 40%）。不断减少的奥地利牲畜数量的减排对气候中和农业做出了重要贡献：过去 20 年畜牧业 CH 的减少使当前奥地利的总 CO-we 减少了 16%。正如我们在这里为奥地利畜牧业所展示的那样，持续减少 CH 是应对短期气候危机的有效选择。需要强调的是，相对较低的 GWP*不应被解释为进一步 CH 排放的让步，而应被视为（额外）变暖的实际减少。
