A variety of recent studies have agreed that, for the world as a whole, enough land and water resources exist to meet any plausible needs of the human population over the next 50 years. This global resource adequacy notwithstanding, however, certain critical geographical regions or social group already face difficulties in satisfying their basic development objectives with the resources available to them. Such difficulties may be expected to expand and intensify over the next 50 years unless constraints on resource availability and use are significantly relaxed. The most important constraints include inadequate local resource supplies, technical knowledge, or purchasing power, as well as political and trade barriers, environmental limits, inefficiency, and waste. [...]