Livestock are responsible for 12% of anthropogenic greenhouse gas emissions. Sustainable intensification of livestock production systems might become a key climate mitigation technology. However, livestock production systems vary substantially, making the implementation of climate mitigation policies a formidable challenge. Here, we provide results from an economic model using a detailed and high-resolution representation of livestock production systems. We project that by 2030 autonomous transitions toward more efficient systems would decrease emissions by 736 million metric tons of carbon dioxide equivalent per year (MtCO(2)e.y(-1)), mainly through avoided emissions from the conversion of 162 Mha of natural land. A moderate mitigation policy targeting emissions fromboth the agricultural and land-use change sectors with a carbon price of US$10 per tCO(2)e could lead to an abatement of 3,223 MtCO(2)e.y(-1). Livestock system transitions would contribute 21% of the total abatement, intra-and interregional relocation of livestock production another 40%, and all other mechanisms would add 39%. A comparable abatement of 3,068 MtCO(2)e.y(-1) could be achieved also with a policy targeting only emissions from land-use change. Stringent climate policies might lead to reductions in food availability of up to 200 kcal per capita per day globally. We find that mitigation policies targeting emissions from land-use change are 5 to 10 times more efficient-measured in "total abatement calorie cost"-than policies targeting emissions from livestock only. Thus, fostering transitions toward more productive livestock production systems in combination with climate policies targeting the land-use change appears to be the most efficient lever to deliver desirable climate and food availability outcomes.

农业气象观测质量的高低直接关系到气象为农业服务的水平和效果,其中作物观测和发报是农气观测工作的核心.本文针对陕西农气观测和编报提出了提高农气观测质量的方法.

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通过野外调查和室内饲养测定,对枸杞蚜虫世代发育与温度的关系,有效积温和发育起点温度进行了研究,结果表明:枸杞蚜虫在银川地区每年约19.65代.完成一代需有效积温88.36日·度,发育起点温度为8.909℃.7～8月持续高温对枸杞蚜虫种群有抑制作用.