The world's population continues to grow at an accelerated pace. It is estimated to hit 9.3 billion in 2050, an increase of 50 percent from 6.1 billion in 2001, according to the latest annual report from the U.N. Fund for Population Activities. The key message from the report is that sustainable social development centering on economic growth is impossible without integrated global efforts to eradicate poverty and protect the environment.

Curbing global population growth is a daunting challenge that can best be met through international cooperation. Japan, which is internationally committed to development, must continue to play an active role in these efforts. The Japanese government, faced with a fiscal crisis of its own, plans to cut its foreign aid budget by 10 percent in fiscal 2002. However, this need not translate into an automatic reduction in the nation's contributions to international population programs.

The world's population has doubled in just four decades, from 1960 to 2001. The current figure, to be more exact, is 6.134 billion, according to the U.N. document. Half a century from now, the world will be inhabited by 7.9 billion people, even if fertility rates remain low. The figure will be 10.9 billion if the birth rate goes up. The most likely estimate, one based on a moderate rise in fertility, is 9.3 billion. Most of the growth will occur in the developing countries.

The report puts emphasis on environmental factors, such as water, food and climate change. The availability of water, it says, may set limits to sustainable development. To avoid that, it is essential to make proper use of water resources and prevent water pollution. The average per capita amount of water required for living is estimated at 50 liters per day. The report predicts, however, that the number of people unable to fill this requirement will reach 4.2 billion, or 45 percent of the total population, by 2050.

As for food, the problem is that population is increasing faster than food production in developing countries. Because of this, an estimated 800 million people suffer from chronic malnutrition, and another 2 billion face possible food shortages. This points to the need for international cooperation to increase crop harvests in developing regions.

Regarding climate change, the report says the aggregate volume of carbon dioxide discharged into the atmosphere through human activity increased 12 times in the last century, contributing to global warming. Climate change, it warns, will worsen water shortages and spread tropical diseases, posing serious threats to public health. And it calls for statutory restraints on CO2 emissions in developing countries as well.

Aside from these and other environmental problems, chronic poverty remains a heavy drag on development. The numbers are appalling: 86 percent of the world's consumer spending is concentrated in the rich countries, which make up 20 percent of the global population; by contrast, consumption in 20 percent of the poor countries accounts for just 1 percent of the world total.

Half the people in the world live on $2 a day or less. Children in developed countries each consume -- and in the process pollute the environment -- 30 to 50 times as much as those in developing countries. Sixty percent of the 4.9 billion people in the developing world do not have access to basic health services. Unclean water and poor sanitation each year claim the lives of more than 12 million people in the developing world.

Women hold the key to curbing population growth. It is important, as the report points out, to improve women's social status and guarantee their rights to reproductive health -- including the right to decide for themselves how many children to have. Progress has already been made. In the past three decades the number of children per woman in the developing countries has dropped below three; it is estimated it will further decline to 2.17 by midcentury.

In releasing the report in Tokyo, UNFPA Secretary General Thoraya Ahmed Obaid noted a downward trend in the rate of population growth. With more than 60 percent of families in the developing countries taking part in family-planning programs, the average number of family members has dropped by nearly 50 percent, he said, adding that if this trend continues, it will help to protect the environment, promote development and eradicate poverty.

To sustain this trend it is also necessary for the developed countries and their nongovernmental organizations to step up their support and cooperation. Japan, the largest contributor to the UNFPA and related programs, has its work cut out. In spite of its tight finances, the Japanese government needs to keep up its financial, technical and other commitments to the stabilization of the global population.