Behind these shortages lies a population explosion that shows no signs of abating. It took humanity until 1800 to reach 1 billion in strength; not until 1927 did we reach 2 billion. Then things really started rolling:
It took a while for world population to really get started, but during the 20th century, we've doubled -- then redoubled our numbers.
Between 1978 and 1992, average income per person rose 227 percent, from $1,973 to $4,473 (in 1994 dollars, using data from the World Bank). This means that per-person economic output more than doubled in just 14 years. During the same period, world population grew 27 percent, from 4.30 billion to 5.44 billion.
It's not just the numbers, it's the intensity
As population grows, so does overall economic activity. For reference, the world gross domestic product -- the sum of all goods and services -- was $35.11 trillion in 1996. But more interesting than the absolute number are the trends in population and individual income. When you multiply each individual's activity by the number of people, you get a rough estimate of global economic activity.
At today's level of fertility, Earth would be a very crowded place in another 50 years. Population growth is expected to slow, but by how much?
Source: Population Reference Bureau and United Nations.
And while the statistics can be questioned, the trend toward rapidly increased industrialization is stark. That would be good for economists and many individuals, but for the environment, it might be a different story, since each dollar spent on food, clothing, shelter, transportation or housing has environmental consequences (see "A Special Moment" in the bibliography).
With more dollars chasing more natural resources, this colossal growth is likely to intensify the shortages we're discussing. Per capita grain harvests peaked in 1984, and some scientists have estimated that Earth's carrying capacity -- its ability to sustain a population -- at between 7.7 and 12 billion people. It's unlikely that Earth's population will be much less than 10 billion 50 years from now. [Population: six billion strong -- or weak?]
Like fish and chips? Sorry. As far as fish are concerned, the chips are really down.
Even with the help of two reference librarians, The Why Files couldn't locate predictions for global economic growth, so we did some elementary calculations. If population and per-capita income grow as fast over the next 14 years as they did during the 14-year period we just examined, the world economy will grow 287 percent -- almost tripling -- measured in constant dollars.
