The building’s windows feature picturesque views of the Hudson River. But Gu, like some of his colleagues, worked with his back to the view. The analysts were framed in their offices by gray metal bookcases piled high with papers.
For Afghanistan, Gerland, who sits within shouting distance of Gu, had to use every resource in his arsenal of numbers. The numbers would have to tell him how Afghans live, migrate, give birth and die.
Without a more recent census, he reached for data provided by a demographic survey financed by the U.S. Agency for International Development. In the past 50 years, surveys and questionnaires have created rich sources of information on people in developing countries, he said.
In addition, agencies such as the U.S. Centers for Disease Control and Prevention collect information while providing health care to tens of thousands of people worldwide. The United Nations Children’s Fund, UNICEF, collects data from families when it gives vaccinations.
Most nations have a statistical office with birth certificates, child mortality records and death certificates that help paint a portrait of their populations. Some Scandinavian nations go even further, providing population registers, a sort of national I.D.
“We can’t do this in an office without getting information from somewhere,” Gerland said.
There’s one vexing problem that U.N. analysts are always hard pressed to resolve, even for a developed nation such as the United States: how to account for citizens who hide from census takers, and for the undocumented immigrants, estimated to total more than 11 million in the United States alone.
Migrant workers in Arab nations such as Qatar and the United Arab Emirates also are a demographer’s nightmare. They comprise more than half the populations of those countries, and no one knows how they come and go, or with whom they have children in foreign lands or at home.
“It’s forensic kind of work,” said Gerland, the analyst. “Pieces of information have to make sense. You have to resolve it.”
“The work,” said Gu, “is very hard.”
Heilig, the division chief, said the analysts are supported by staff, and their work is reviewed by other offices in the United Nations and by commissions representing Latin America and the Caribbean. Errors are corrected.
The U.N. Population Division is one of the oldest units in the Secretariat, organized in 1949 when developing countries clamored for population reports. As Europe’s colonies were liberated, the new governments wanted to know the state of their populations.
The first U.N. count started with an estimate of 2.5 billion in 1950. Today the findings are packaged into compact discs, wall charts and books and given to the World Health Organization, the Food and Agricultural Organization, the World Bank and other offices in the U.N. system to help determine aid needed mostly in developing nations.
On a white board in his office, Heilig wrote worrisome notes on how the population is shifting. Even if things go as expected, Asia’s population boom will decline after 2050, but Africa’s will increase by 1.5 billion. African nations such as Nigeria, Senegal, Uganda and Rwanda are rife with ethnic and tribal groups that find strength in numbers. In 20 years, the population of today’s least developed countries will surpass the population of more developed regions.
“I think fertility will decline in Africa, the question is how fast,” said John Bongaarts, vice president at the Population Council, an international non-profit group that conducts research on poverty and AIDS. If it doesn’t, “you can end up with a very large number of people living in terrible conditions and slums.”
Bongaarts paused for a second and voiced a thought that no population projection can precisely answer. “Who knows what will happen.”