Scarcities of Food and Fresh Water.

Productive agricultural systems have contributed to economic progress in many countries, both developed and less developed. The Green Revolution of the 1970s enabled some developing countries to become net exporters of food. Yet, global population growth during and since the Green Revolution is continuing to consume more and more of the expanding food base, leading to a decline in per capita availability of cereal grains on a global basis over the last 15 years.

The world's agricultural systems rely substantially on increasing use of fertilizers. But now, the world's farmers are witnessing signs of a declining response curve, where the use of additional fertilizer yields little additional food product. At the same time, fertilizers and intensive cropping lower the quality of soil. These factors will more and more limit the possibilities of raising food production substantially and will, at a minimum, boost relative food prices and resulting hunger for many. So will the mounting resistance of pests to insecticides, which are used increasingly by the world's farmers. On a global basis, 37 percent of food and fiber crops are now lost to pests.

At the same time, nitrogen-based fertilizers are yielding nitrous oxide, which adds to the greenhouse effect of the carbon dioxide humans produce.
As an illustration of food problems to come, Lester Brown of WorldWatch Institute has made projections regarding food demand by China and India through the year 2030. Because of industrialization leading to loss of agricultural land, population growth, and the demand for more meat instead of grain as incomes rise, China is projected to need to import 240 million tons of food annually by the year 2030. The same projections show India (currently an exporter of food) needing to import 30 million tons a year. Yet, total world agricultural trade is currently just 200 million tons of grain or grain equivalent, and that amount is decreasing as the exporting countries consume more and more of their own food products. Accordingly, the increasing demand for food imports by growing economies like China's will almost certainly drive the price of food up over the next 30 years, virtually ensuring that more people elsewhere will suffer from starvation. Historically, Western countries have shown no inclination to undergo a dramatic decline in their own quality of life (including greatly reducing consumption of meat and poultry) in order to assist poor countries with grain exports. And so the world is likely to witness severe starvation and economic dislocation over the next 30 years.

At the same time, shortages of water are at a crisis point in many countries. At least 400 million people live in regions with severe water shortages. By the year 2050, it is projected to be approximately two billion. Water tables on every continent are falling, as water is pumped out at far greater rates than rainwater can replenish in order to provide irrigation for agriculture. India, for example, is pumping out its underground aquifers at twice the rate of natural replenishment.

Humans are already using half of the globe's products of photosynthesis and over half of all accessible fresh water. Long before human demand doubles again, the limits of the ecosystem's ability to support people will become dramatically evident.