AFTER decades of steady growth, the world's food supply is no longer keeping up with population increases. Production of meat, fish, and grains per person has slowed to the point where the earth may have reached its ``carrying capacity,'' with the result that nearly one in five (or 1 billion people) is malnourished.
This is the sobering conclusion of the Worldwatch Institute's annual ``State of the World'' report, which was released over the weekend.
While solutions are to be found in many aspects of environmental and economic policy, as well as in some emerging technologies, the report's authors say the key is stabilizing population growth.
Not everyone accepts Worldwatch's somewhat Malthusian analysis, which is based on information gathered by national governments, United Nations organizations, and private researchers.
Ronald Baily, author of the 1993 book, ``ECO-SCAM: The False Prophets of Ecological Apocalypse,'' calls it ``a wonderful propaganda tool for apocalyptic environmentalism.'' Other conservative analysts and commentators denounce it as well.
But ``State of the World,'' now in its 11th year and widely distributed among political and business leaders, enjoys considerable credibility and influence. Printed in 27 languages, it is used in about 1,000 university courses.
Vice-president Al Gore Jr.'s ``Earth in the Balance'' followed much the same line, as did the 1992 UN Conference on Environment and Development (the ``Earth Summit'') in Rio de Janeiro.
The growth in annual food production peaked in the 1980s, according to data gathered by the Worldwatch Institute, a Washington-based think tank.
Between 1989 and 1993, the fish catch per person dropped 7 percent. After peaking in 1984, per capita grain output by last year had fallen 11 percent. The picture on animal protein from grazing animals is less clear, but here too declines can be expected since the amount of rangeland per person is decreasing.
Overharvesting of oceans has become widespread. The UN Food and Agriculture Organization reported last year that all 17 major fishing areas around the world have reached or exceeded their natural limits with nine of those in serious decline.
Most of the increase in grain yields during the post-World War II era can be credited to fertilizers. The use of fertilizers climbed from 14 million tons annually to a peak of 146 million tons in 1989. But since 1984, the increase in grain production per ton of fertilizer applied has dropped sharply.
In essence, writes Worldwatch president Lester Brown, most of the payback on technologies like agricultural chemicals has been achieved. Although newer technologies (such as desalting sea water and biotechnology) hold some promise, they are not a panacea, he argues.
``In summary, there are innumerable opportunities for expanding food production, many of them locally unique,'' Mr. Brown writes. ``But all the identifiable ones are small, adding a little [here] and a little there.''
Noting such global problems as deforestation, desertification, and water scarcity, Worldwatch vice-president Sandra Postel warns that ``the central conundrum of sustainable development is now all too apparent: Population and economies grow exponentially, but the natural resources that support them do not.''
World population, which is increasing by about 90 million a year, now stands at 5.5 billion. According to the UN's medium projection, that figure will rise to 8.9 billion by the year 2030 and level off at 11.5 billion by 2150.
Most of that increase will come in developing countries, where many people in a relatively young populace are now reaching child-bearing years, and where food supplies already are a problem.
For example, United States government demographers estimate that Nigeria will grow from its 1990 level of 87 million people to 278 million by 2030; Bangladesh from 114 million to 243 million; and India from 853 million to nearly 1.5 billion (more than China today).
While food production may increase somewhat, the carry capacity of many areas - defined as ``the largest number of any given species that a habitat can support indefinitely'' - has been exceeded or will do so soon.
``The bottom line is that the world's farmers can no longer be counted on to feed the projected additions to our numbers,'' Brown says. ``Achieving a humane balance between food and people now depends more on family planners than on farmers.''
The Clinton administration in 1993 reversed the policy of previous Republican administrations and restored US funding for the UN Population Fund and the International Planned Parenthood Federation. Later this year, UN member countries will meet in Cairo for the third International Conference on Population and Development.