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The world’s population grew strongly in the 1800s and 1900s, but growth has now started to slow down as a result of people having fewer children, which – in the long run – will lead to a stabilisation of global population figures, say scientists at Norway’s CICERO Center for International Climate Research. Photo by Chuttersnap / Unsplash.

The world’s population grew strongly in the 1800s and 1900s, but growth has now started to slow down as a result of people having fewer children, which – in the long run – will lead to a stabilisation of global population figures, say scientists at Norway’s CICERO Center for International Climate Research. Photo by Chuttersnap / Unsplash.

Population growth is moving in a climate-friendly direction

Climate news - News and opinions about climate science

Published 13.12.2018

Higher living standards have led to a slow-down in global population growth. This is good news for the climate because it will lead to lower growth in carbon emissions, say scientists at CICERO Center for International Climate Research.

“The perception that world population is growing at an exponential rate is incorrect. Global population growth was high in the 19th and 20th centuries, but it is now in the process of slowing down because people have started to have fewer children,” says CICERO researcher and human geographer Nina Bergan Holmelin.

“Global population figures will eventually stabilise. Today’s increase in population is primarily caused by a decline in child mortality and increasing life expectancy,” Holmelin says.

“This means that the world’s population will continue to increase in the coming decades, although the growth rate is declining,” she adds.

World population growth rate 1950-2100 (percent)

Reference: United Nations, Department of Economic and Social Affairs, Population Division (2017). World Population Prospects: The 2017 Revision.

In order to limit global warming to 1.5°C by 2100, we will need to cut carbon emissions by 45 percent by 2030, according to the latest report by the UN Climate Panel (IPCC) – the so-called 1.5°C report – which was published on 8 October.

Global population growth was high in the 19th and 20th centuries, but it is now in the process of slowing down because people have started to have fewer children.

Nina Bergan Holmelin, researcher at CICERO.

The report contains several different scenarios for how we can reach the 1.5°C target. Growth in the world’s population is one of many factors that will determine how difficult it will be to achieve the target.

“The UN Climate Panel does not say that we have to reduce population growth; only that higher population growth will make the 1.5°C target more difficult to reach, but not impossible,” says Robbie Andrew, senior researcher at CICERO.

Large growth uncertainties

The world’s population is currently around 7.6 billion people, and this number is increasing by about 83 million every year, according to a report published by the UN in 2017.

According to this report, the world’s population will reach 9.8 billion people by 2050, and 11.2 billion by 2100. The UN says, however, that these numbers are highly uncertain because global population growth will depend on how much effort is put into achieving a speedy decline in birth and death rates.

The UN Climate Panel does not say that we have to reduce population growth; only that higher population growth will make the 1.5°C target more difficult to reach, but not impossible.

Robbie Andrew, senior researcher at CICERO.

“When health care and living standards are improving and people get better access to medication and vaccines, the mortality rates decline. And when people can begin to trust that their children will survive childhood and not die from common diseases, the fertility rates will eventually decline as well,” says Holmelin.

Reference: United Nations, Department of Economic and Social Affairs, Population Division (2017). World Population Prospects: The 2017 Revision.

Longer life expectancy, lower child mortality and fewer children

Reference: United Nations, Department of Economic and Social Affairs, Population Division (2017). World Population Prospects: The 2017 Revision.

In 1950, life expectancy in the world averaged 47 years, the average number of children per woman was five, and as many as 14 percent of the children died before reaching the age of one.

In comparison, the children born today can expect to reach 70 years of age, and infant mortality has fallen to 3.5 percent and is expected to decline further in the coming years, according to Holmelin.

Moreover, the global average number of live births per woman has sunk to 2.5. When the global fertility rate reaches 2.1 children per woman, the population figure will stabilise over time.

“The transition from high to low death and birth rates has already happened in Europe, North and South America and, to a large degree, also in Asia. It is mostly nations in sub-Saharan Africa that are still experiencing high population growth, but here death rates started falling much later than in other regions,” says Holmelin.

“Fertility rates have peaked and are now declining in many African countries, so things are moving in the right direction. And a lot is being done to speed up this process, such as increased efforts on education, poverty reduction, improved nutrition, health care and sanitation, social security, vaccines and better access to contraception,” she says.

Important for economic growth

“Lower population growth is important for increasing living standards in poor countries, and when both the access to birth control and the education level among women increase, the fertility rate falls. Education makes women become more aware of the fact that they can do a lot more than just have children,” says Andrew.

Housing and child care are expensive, and if you are also struggling to get a mortgage and do not have a stable income, you will think long and hard before you decide to have more children.

Solveig Glomsrød, senior researcher at cicero.

According to CICERO scientist and economist Solveig Glomsrød, birth rates also tend to fall as a result of increased urbanisation caused by economic growth. For many people, urbanisation means higher costs of living and moving far away from relatives willing to babysit.

“Housing and child care are expensive, and if you are also struggling to get a mortgage and do not have a stable income, you will think long and hard before you decide to have more children,” says Glomsrød.

Emission cuts needed

Improving living standards in poor countries is an important development goal, but it will also be beneficial for the climate because it will lead to lower population growth. Developed countries thus need to focus on cutting their own emissions at the same time as they are assisting poorer countries in getting on the right track, according to the CICERO scientists.

“The world’s average temperature has already increased by around 1°C as a result of climate change, but this is not due to climate gas emissions in poor countries,” says research director Bjørn Hallvard Samset at CICERO.

“The U.S. is among the countries in the world that are expected to see the highest population growth – mainly due to immigration and longer life expectancy – with an increase of 128 million inhabitants by 2100. I am much more worried about this than about population growth in poor countries because emissions per U.S. inhabitant are enormous, and the country has no plans to cut them,” Andrew adds.

Mitigation efforts in poorer countries

Countries in the western world can also contribute to ensuring that population growth in poorer countries will not lead to a large increase in greenhouse gas emissions, the researchers say. One way to do this, is to influence what kind of energy sources will be developed.

The world’s average temperature has already increased by around 1°C as a result of climate change, but this is not due to climate gas emissions in poor countries. 

Bjørn Hallvard Samset, research director at CICERO.

The International Energy Agency (IEA) expects the world’s energy demand to increase by more than 25 percent by 2040 due to population growth and rising prosperity. Most of this increase will come from urban areas in developing countries, according to the agency’s report World Energy Outlook, which was published on 13 November.

“There is great potential for influencing the future energy mix, especially in countries that currently have poorly developed infrastructure. New energy sources do not have to be based on fossil fuels,” says Holmelin.

In the recent 1.5°C report, the IPCC highlighted four possible pathways towards 2100. All of these will require an almost complete phaseout of fossil fuels used for energy production, unless technologies used to capture and store carbon (CCS) become widespread, explains Samset.

"The global energy system needs to change – radically – if we are to achieve any kind of low warming target," he says.