Meat, especially beef, requires far more land, water and feed grain per calorie delivered than plant-based staples do. As incomes rise across the developing world, diets are shifting toward greater meat consumption, following the same trajectory today's wealthy nations took decades ago. If global average diets converge toward current wealthy-nation consumption patterns, the additional land and water demands could outstrip what the planet's remaining arable land and freshwater can sustainably provide.

What is the critical message conveyed by the passage given above?