Earth's population could shrink in a few decades

"As women become better educated and gain access to birth control, they don't want to have as many children," says Professor Chris Murray, head of the Institute for Health Metrics and Evaluation (IMHE) in the United States.

Murray is in Trondheim in connection with NTNU's music and science festival, The Big Challenge, to talk about Global Burden of Disease (GBD), the world's largest health survey. He is the director of the research programme, which addresses the factors that lead to illness and death worldwide.

Some of the findings could have major consequences for the future of our Earth. Fewer people would be good news for our planet.

Low birth rates

The UN still maintains that the world's population will reach 11 billion by the year 2100, but this is by no means certain, according to the world-renowned professor.

"We've been concerned about overpopulation since the 1960s. But now there are several regions in the world where people aren't having enough children to replace themselves," Murray says.

In short, this means that we'll see a decline in population. Birth rates are falling in several countries. In order for the population to remain reasonably stable, every woman needs to have, on average, just over two children. The birth rate is below this in about half the countries and territories of the world. In Singapore and Taiwan, for example, it is down to 1.2 births per woman.

"We're the only species that has ever favoured shrinking the population," Murray says.

Women will decide

The reasons are clearly complex, but women's increased education and opportunities undoubtedly play a role.

China recently abolished its one-child policy.

"We saw a small spike in the birth rate right afterwards, but now it's going down again," says Murray.

Some women who were thinking of having children or having more children took the chance soon after the policy shift. But since then the birth rate has stabilized again.

More children surviving

Another important factor behind lower birth rates is that a much larger proportion of children are surviving than ever before. In 1950, more children under the age of five died than died in any other age group. Now people over 65 comprise the largest population group.

"It's no longer as critical to have more children to make sure some of them grow to adulthood," Murray says.

Even though average life expectancy is also rising, the lower birth rate may still cause the total number of people to fall in several places. According to IMHE data, this is the most likely development.

Women's rights could be threatened

One possible future problem is that authorities in non-democratic countries that want their population to increase could resort to drastic methods if encouragement is not enough. "They might try to increase birth rates by restricting women's rights to self-determination. We have to be aware of this possibility," says Murray.

A few decades ago, Romania made abortion illegal more or less overnight. Similar tactics were employed in the Soviet Union.

An extensive article is expected this fall that will go into depth on developments in the world's population for each country.

Finding big differences

Worldwide, we see great inequalities within health, and also within countries. Social status contributes to determining not only how long you live, but also what types of illnesses you are exposed to. As the standard of living rises for an increasing proportion of the population, people are indeed living longer, but more people are also vulnerable to lifestyle problems like higher BMI and high blood pressure.

World health surveys began in 1991 when the World Bank discovered that no good figures were available to indicate what people were dying from worldwide. Murray was already present when the first survey results were published in 1996 and 1997. Later, GBD expanded its research to include non-lethal diseases. Today, 195 countries and territories are included, and 84 possible risk factors linked to 359 disease conditions are considered.

Murray works closely with Professor Terje Andreas Eikemo, head of NTNU's Centre for Global Health Inequalities Research (CHAIN). Eikemo likes to call GBD "the world's largest calculation." CHAIN is involved in researching how education affects our health.