Department of Earth System Science, University of California, Irvine, Irvine, CA, USA.
School of Global Policy and Strategy, University of California, San Diego, San Diego, CA, USA.
Nature. 2021 Jan;589(7843):554-561. doi: 10.1038/s41586-020-03138-y. Epub 2021 Jan 27.
Historically, human uses of land have transformed and fragmented ecosystems, degraded biodiversity, disrupted carbon and nitrogen cycles and added prodigious quantities of greenhouse gases (GHGs) to the atmosphere. However, in contrast to fossil-fuel carbon dioxide (CO) emissions, trends and drivers of GHG emissions from land management and land-use change (together referred to as 'land-use emissions') have not been as comprehensively and systematically assessed. Here we present country-, process-, GHG- and product-specific inventories of global land-use emissions from 1961 to 2017, we decompose key demographic, economic and technical drivers of emissions and we assess the uncertainties and the sensitivity of results to different accounting assumptions. Despite steady increases in population (+144 per cent) and agricultural production per capita (+58 per cent), as well as smaller increases in emissions per land area used (+8 per cent), decreases in land required per unit of agricultural production (-70 per cent) kept global annual land-use emissions relatively constant at about 11 gigatonnes CO-equivalent until 2001. After 2001, driven by rising emissions per land area, emissions increased by 2.4 gigatonnes CO-equivalent per decade to 14.6 gigatonnes CO-equivalent in 2017 (about 25 per cent of total anthropogenic GHG emissions). Although emissions intensity decreased in all regions, large differences across regions persist over time. The three highest-emitting regions (Latin America, Southeast Asia and sub-Saharan Africa) dominate global emissions growth from 1961 to 2017, driven by rapid and extensive growth of agricultural production and related land-use change. In addition, disproportionate emissions are related to certain products: beef and a few other red meats supply only 1 per cent of calories worldwide, but account for 25 per cent of all land-use emissions. Even where land-use change emissions are negligible or negative, total per capita CO-equivalent land-use emissions remain near 0.5 tonnes per capita, suggesting the current frontier of mitigation efforts. Our results are consistent with existing knowledge-for example, on the role of population and economic growth and dietary choice-but provide additional insight into regional and sectoral trends.
从历史上看,人类对土地的利用改变并破坏了生态系统,降低了生物多样性,扰乱了碳氮循环,并向大气中排放了大量温室气体(GHGs)。然而,与化石燃料二氧化碳(CO)排放不同,土地管理和土地利用变化导致的温室气体排放趋势和驱动因素(统称为“土地利用排放”)尚未得到全面系统的评估。在这里,我们提供了 1961 年至 2017 年全球土地利用排放的国家、过程、温室气体和产品特定清单,我们分解了排放的关键人口、经济和技术驱动因素,并评估了不确定性和结果对不同核算假设的敏感性。尽管人口(增长 144%)和人均农业产量(增长 58%)稳步增加,以及每单位土地使用排放(增长 8%)略有增加,但农业生产所需土地面积(减少 70%)的减少使全球年度土地利用排放相对稳定在 11 吉吨 CO2 当量左右,直到 2001 年。2001 年后,由于每单位土地面积排放增加,排放每十年增加 2.4 吉吨 CO2 当量,到 2017 年达到 14.6 吉吨 CO2 当量(约占人为温室气体排放总量的 25%)。尽管所有地区的排放强度都有所下降,但随着时间的推移,各地区之间仍存在很大差异。排放最多的三个地区(拉丁美洲、东南亚和撒哈拉以南非洲)主导了 1961 年至 2017 年的全球排放增长,这是农业生产和相关土地利用变化迅速和广泛增长的结果。此外,不成比例的排放与某些产品有关:牛肉和其他一些红色肉类仅占全球卡路里的 1%,但占所有土地利用排放的 25%。即使土地利用变化排放可以忽略不计或为负,人均 CO2 当量土地利用排放仍接近 0.5 吨/人,这表明目前缓解努力的前沿。我们的结果与现有知识一致,例如人口和经济增长和饮食选择的作用,但提供了对区域和部门趋势的更多见解。