CONSUMERS who fuss at the cost of salmon may not give a thought to world population growth. Yet those high prices could be the first installment of a population-driven food crunch.
That message emerged from discussions at the annual meeting of the American Association for the Advancement of Science. It is a warning that detrimental effects of rapid population growth could be felt on a global scale much earlier than many experts had anticipated.
As agronomist David Pimentel of Cornell University in Ithaca, N.Y., explained, the notion of a population ``bomb'' that will explode sometime in middle of the next century is misleading. ``Nature doesn't work that way,'' he said. ``It nickels and dimes you to death.'' He expects problems to develop piecemeal over time as the demands of the growing population run up against the constraints of finite resources.
Lester Brown, who heads the Worldwatch Institute in Washington, says the shortages that have driven up the prices of seafood are an early example of this. He expects the next example to develop over the next few years as China - which no longer can feed itself - becomes a major buyer in the world grain market.
China has the cash to compete aggressively for grain supplies, half of which come from the United States. Mr. Brown explained that China could well end up competing directly with US consumers for US grain. This could drive up prices of cereal foods and meat and dairy products from grain-fed animals in American supermarkets. And that, Brown observed, ``could quickly become a political issue.''
Seafood shortages - a result of all the world's major fisheries being overfished now - illustrate a fundamental aspect of the problem. These are not shortages that can be overcome by better management of fisheries. Also, fish farming and other forms of aquaculture - important as they may be in the long run - can't develop fast enough to meet global demand. ``We seem to have hit the wall several years ago when the [annual] catch reach 100 million tons. It's been somewhat lower since then,'' Brown said.
Dr. Pimemtel sees other constraints on land-based agriculture. Water shortages are developing as cities out compete rural areas for limited supplies in many countries. Millions of fertile acres are lost every year to soil erosion, salt buildup, and industrial development.
Brown sees the same constraints. They can be offset to some extent by crop improvements and new technologies to boost crop yields. But Brown says these improvements won't be able raise the annual global grain harvest, now at 1.7 billion tons, to more than about 2 billion tons.
That's enough grain to support a world population of 2.5 billion at the US level of consumption of 800 kilograms a year per person. It would support 5 billion people at Italy's level of 400 kg, 7.5 billion people at the current Chinese level of 300 kg, and 10 billion people at India's level of 200 kg. But the world already has 5.7 billion people. Noting all this, Brown said that clearly this situation means that many people will continue to be ill fed.
That would be bad enough. But Brown, Pimentel, and other experts who discussed this at press conferences here, say this challenge is exacerbated by the fact that many people living at the lowest grain consumption levels are becoming industrialized. As their affluence expands, they want to move up to the Italian or even the American level. And they want to do it as fast as they can afford it.