Synthetic fertiliser shortage never ending, lower crop output per input, massive population growth from 2.5 billion to 8.5 billion in ~80 years thanks to synthetic fertilizer and industrialisation. So without synthetic fert, without diesel (farming is very diesel heavy) cheap labour and with a huge global debt making capital investment tightly aligned with cost/benefit then we likely can't produce and transport food for all the people who now live 100's kilometers from it's production. I'm not hard claiming 3 billion but i feel it's a fair assessment weighing agricultural innovations over the last 80 years against the probable the loss of abundant fert/oil/labour/water/pollinators/biosecurity programs