Most people in most countries of the world make do on around 200kg of grain per year. Between 1950 and 1990 the world grain harvest tripled. But at the start of 1996, world grain stocks were the lowest on record. This growth has almost stopped. So the number of people with a steak in the future is already falling, as world populations soar.
Water is already a huge problem and getting more problematic almost everywhere.
Humans can scrape by on a few litres every day, but it takes 500 litres of water to grow 1kg of wheat. Meanwhile the increases go on. In the last decade, the growth in population equalled the population of the whole world in 1600. Every five days there are another million or more mouths to feed.