Even as populations grow, the global supply of arable land declines due to industrial pollution, desertification, salination (e.g. by accumulation of fertilizer, or by seawater permeation of soil), erosion, and other factors.
人口增加，全球可耕地卻因工業污染、土地沙漠化、沖蝕、鹽化（肥料中的元素累積或海水浸潤）等問題而逐日縮減。