The population of the world is increasing so fast that if something isn't done about it, scarce resources will threaten lives.

Isn't it?

No, says Dr. Joseph Chamie, director of the United Nations’ Population Division. The Population Division is separate from the U.N.'s Population Fund, which has drawn criticism from watchdog groups that question its “ideological” use of data.

Chamie has worked with demographic numbers for 28 years. Prior to his work at the United Nations, Chamie and his wife served in the Peace Corps in India. He spoke with Register staff writer Tim Drake from his office in New York.

For the past 20 years, all we've heard about is the coming population explosion. Your recent data suggesting low birth rate and fertility decline seems to fly in the face of all the previous media coverage. What's going on?

I'm fortunate to be a demographer at this point in history. It's like being a sailor in the 15th century, traveling with Columbus. It's the most exciting period in demographic history.

The period of rapid population growth is not over. The second half of the 20th century was record-breaking with how many people we added. On the average, we're adding about 77 million people every year. Ninety-nine percent of that is occurring in the developing world. Twenty-one percent of that is occurring in India.

In ancient times, we had high births and high deaths. Religious leaders said, “Go forth and multiply.” There were no antibiotics. Life was harsh, and people died. In order for your family and community to survive, you had to have lots of births. We were able to make great scientific achievements in bringing down mortality. After World War II, that spread to the developing world. Life expectancy at the beginning of the century was around 30. By the end, it was at 65. I consider that humanity's greatest achievement. You can see your wife survive child-bearing, and see your grandparents and great grandparents in old age. Low mortality is agreed to by every country and culture. It's a precondition for development.

The gap between births and deaths is now closing. It's a part of modern life. We now have low deaths and low birth rates. We're now moving to more countries having low fertility.

In fact, isn't there a new problem — fertility rates that are too low?

One in three countries has fertility below replacement levels. This is increasingly a concern in countries like Italy, Korea and Japan. If you have no immigrants, you will get smaller and older quickly. Neither rapid population growth nor rapid population decline are sustainable for any length of time.

Which countries face the biggest crisis?

We estimate that by mid-century, there will be 43 countries that will be smaller than they are today, some substantially. The Baltic countries could have a decrease of 30% or more. Italy will have 20% less. Hungary will decrease by 25%. Japan is likely to have a 14% decline. In Switzerland, it will be 20%. In Cuba, 10%. In Germany, 5%.

Why is this troubling?

The population aging and decrease is the result of voluntary choices made by millions and millions of couples. This is the first time in modern history that we've had this, so it's uncharted waters.

Can immigration make up for the loss?

Immigration can make a big difference in labor force, but it cannot solve the aging problem. If fertility is low and you bring in immigrants, it changes the composition of the receiving country. The U.S., Canada and Australia have a history of dealing with this. Japan, Italy and Korea have not had that experience.

If Italy would like to keep its population constant, it would need to bring in 250,000 people every year for the next 50 years. If it would like to keep its labor force constant, it would have to bring in 372,000 annually. If it wants to keep the ratio between the working-age population and those over 65 constant, it would have to bring in 2.3 million every year. If we wanted to keep the ratio between working age and those over 65 constant in the U.S., we would have to bring in 12 million each year. That's really not feasible.

Are you a lone voice at the U.N.?

In the early 1950s, population was considered a subject outside the realm of U.N. debate. They felt it should be discussed not in the general assembly, but in the general bedroom. This changed in the 1960s. In our office, we study the entire world. That means those countries that are growing, as well as those that are declining. Some interpret that as political, and the message often gets politicized. They think that I am taking sides. I'm trying to present a comprehensive picture.

What does the future hold in terms of worldwide population?

The future is uncertain. We have a certain range where we expect population to be in the future. Things cannot remain as they are today indefinitely, because some countries would become unreasonably large and some would become unreasonably small. These rates have to come back into balance and harmony.

Next week: “Small Catholic Families.”