Global greenhouse gas (GHG) emissions models generally project a downward trend in CO₂ emissions from land use change, assuming significant crop yield improvements. For some crops, however, significant yield gaps persist whilst demand continues to rise. Here we examine the land use change and GHG implications of meeting growing demand for maize. Integrating economic and biophysical models at an unprecedented spatial resolution, we show that CO₂ emissions from land conversion may rise sharply if future yield growth follows historical trends. Our results show that ~4.0 Gt of additional CO₂ would be emitted from ~23 Mha agricultural expansion from 2015 to 2026, under historical yield improvement trends. If yield gaps are closed expeditiously, however, GHG emissions can be reduced to ~1.1 Gt CO₂ during the period. Our results highlight the urgent need to close global yield gaps to minimize agricultural expansion and for continued efforts to constrain agricultural expansion in carbon-rich lands and forests.

假设作物产量显着提高，全球温室气体（GHG）排放模型通常会预测土地用途变化带来的CO ₂排放量呈下降趋势。但是，对于某些农作物而言，巨大的产量缺口仍然存在，而需求却继续上升。在这里，我们研究了满足玉米需求增长的土地利用变化和温室气体的影响。将经济和生物物理模型以前所未有的空间分辨率进行整合，我们发现，如果未来的产量增长遵循历史趋势，则土地转化产生的CO ₂排放量可能会急剧上升。我们的结果表明，〜4.0 Gt的额外CO ₂在历史上单产提高的趋势下，2015年至2026年约23 Mha的农业扩张将产生温室气体。但是，如果尽快缩小产量差距，则在此期间，GHG排放量可减少至〜1.1 Gt CO ₂。我们的结果表明，迫切需要缩小全球单产差距，以最大程度地减少农业扩张，并继续努力限制富碳土地和森林中的农业扩张。