Should the world start limiting birth rates

Strategies for the future

Unless the unforeseen happens, humanity will grow to almost ten billion people by 2050. Overcoming the gap between rich and poor is a prerequisite for a future worth living: bread must first be put on the table before the poorest begin to worry about their future environment. The fight against poverty must be carried out more seriously than in the past. This would at the same time be a building block for a healthier world - and the prerequisite for a rapid end to population growth.

Increase in population in the industrial age (>> here) and
middle variant of the UN World Population Prospects 2012 for
Population development by 2050. Own illustration.

In the history of mankind, the growth of mankind was the prerequisite for the development we >> took; more people meant more exchange, more creativity, more >> new inventions. But today this growth, in conjunction with the resource consumption of a modern, “western” lifestyle, has crossed a limit where more is no longer better, but increasingly endangers its >> own foundations. Even if the birth rate has long been declining in many populous countries such as India and Bangladesh (phase 3 of the >> demographic transition), further growth in the world population is inevitable due to the large number of young people living here today: half of the population is the fastest growing poorer countries is under 25, and therefore further growth in the short term could only be prevented by major disasters. In the medium and long term, however, a stabilization of the world population is the prerequisite for the fact that for the individual, even with considerably increased efficiency, fewer and fewer resources remain and that the >> ecological footprint of mankind does not finally become too large.

How many people are we going to be?

Predictions about future population growth are always linked to the most intimate decisions people make: they depend on how many couples decide to have how many children in the future. But the >> history of population growth after the industrial revolution shows that there are laws that can be captured with scientific methods. The growth of the population does not go on indefinitely (>> demographic transition). The United Nations regularly assess how the world's population is likely to develop in the various regions of the world. Currently the >> World Population Prospects - The 2019 Revision (English speaking), from which the following numbers are taken.

According to the middle variant of this report, the world population is of 7.7 billion people in 2019 on 8.5 billion people in 2030, on 9.7 billion people in 2050 and up 10.9 billion people in 2100 increase (the confidence interval of 95 percent - i.e. the range in which the information applies with a 95 percent probability - is 9.4 to 10.1 billion people in 2050 and 9.4 to 12.1 billion people in 2100 ). Compared to previous editions of the report, these assumptions have increased - more recent data from some countries show population growth that is higher than previously assumed. How many people we really become depends a lot on that average fertility of the parents (and also the average age at death). Depending on the mortality rate, an average fertility of 2.1 (in industrialized countries) to 2.6 (in poor developing countries) children per pair of parents means that the population remains stable. A higher average fertility means population growth, a lower average fertility means a population decrease. On a global average, the average fertility today is just under 2.5 children; For the middle variant, the UN experts assumed a decrease to 2.2 in 2050 and 1.9 in 2100. If this assumption is not correct, it will have an impact on the future world population: one high variant with an average fertility increase of about 0.5 children, the population would grow to 10.9 billion people in 2050 and 16.6 billion people in 2100; at a low variant with fertility lower by about 0.5 children, it would increase to 8.3 billion people in 2050 and decrease to 6.8 billion people in 2100. The fact that the population continues to grow even with this variant, despite an average fertility of less than 2, is due to the high number of young people who are still reaching reproductive age - the population therefore behaves like a very heavy, fast-moving tanker: they has a very long braking distance.

Population growth is very unevenly distributed, there are big differences between countries. In most developed countries, fertility has long been below the reproductive rate of 2.1 children; here the population is declining (unless the decline is offset by immigration, as is the case in the USA, for example). In recent years fertility has risen slightly to an average of 1.67 children; the UN assumes a further slight increase (to 1.78 in the year 2100), since many couples in affluent countries also want two children and politicians also support them in order to prevent a population decline. In the 47 poorest countries, the reproductive rate is 4.31 children per pair of parents; In the middle variant, the UN experts assume that it will fall to 2.87 children in 2050 and 2.11 children in 2100. In the poorest countries, the population is likely to increase significantly for a long time to come - the greatest effects on population numbers are already having today, populous countries such as India, Nigeria, Tanzania or the Democratic Republic of the Congo. In India in particular, where the birth rate is already falling, the population could grow from 1 billion to over 1.6 billion people due to the high proportion of young people; India could become the most populous country on earth, ahead of China. But the most populous countries like India, China and the USA have long been in phase 3 or 4 of the >> demographic transition; Population growth poses a particular challenge in countries such as Afghanistan, Angola, Nigeria and Uganda, which are in phase 2 and whose birth rate is still very high.

It is true that population growth alone is not the most important cause of our ecological problems today, but the product of the number of people and individual consumption (more on this >> here), and the average population density of the earth becomes clear even with 9.7 billion people in 2050 less than a third of today's density in Germany. But the resource and environmental consumption of our lifestyle has long since exceeded the ecological load-bearing capacity of the earth (more on this >> here), our diet is dependent on animal feed imports; and more and more people in the world are striving for this lifestyle. We have huge potential to achieve improvements through >> more efficient use of resources and >> changed behavior, but in the medium and long term the question will arise anew: If each individual is not to be allowed to consume less and less, the number of people must not continue to grow indefinitely . In addition, there are other aspects: If population growth takes place in poor, unstable countries, young people who are denied basic rights and basic needs will increase instability and extremism in a connected world - the director of the American CIA said in a speech in 2008 that The CIA now consider population growth to be more dangerous than terrorism.

Can population growth be slowed down humanely?

“Population control” is a politically sensitive topic: On the one hand, politics interferes in the most private life decisions, on the other hand, abuse was carried out too often, in which, for example, minorities were particularly intensively “controlled” (e.g. through sterilization). Fortunately, there are other approaches: Most women do not want many children. The number of unintentional pregnancies corresponds roughly to the annual population growth! In many developing countries, however, people do not have access to education and modern contraceptives. The church and some industrialized countries also contribute to this: under George Bush, the USA tied a large part of their development funds to one abstinence-only- Guideline - project partners had to recommend abstinence instead of modern contraceptives; the catholic church preaches abstinence and damn condoms. His successor Barack Obama changed US policy on the third day of his term, and rightly so: Access to all family planning methods is an important step out of poverty - families with fewer children invest more in food, health and education for each child; and thus set a positive cycle in motion: the better the education, especially the girls, the fewer children. The greatest obstacle in the worldwide implementation of this knowledge is that topics such as the emancipation of women (participation in the family and the number of children) and contraception are almost a taboo in many countries around the world due to cultural or religious traditions.

Poverty is the second ally of population growth: poor people have to rely on children as workforce and old-age security - and have many children because they have a higher child mortality rate. High birth rates therefore occur almost exclusively in poor countries or countries with a large proportion of poor people. The highest rates are found in the poorest African countries. Population growth in turn promotes poverty: Land and water have to be shared with more and more people, social systems are not up to the number of people. Many girls get pregnant early, no longer go to school - and remain poor. For this reason, the Fight extreme poverty a fundamental contribution to curb the growth of the world population - the ways to get there are, however, controversial (>> The dispute over development aid).

The millennium of cities

More than half of the world's population now lives in cities (>> more); the United Nations estimates that by 2030 it will be 60 percent. By 2050, 6 billion people could already live in cities, almost twice as many as today. The influx into the particularly fast-growing cities of the emerging and developing countries will continue as long as the life of their residents is better than that in the country. It will therefore be a particular challenge to make the energy and resource consumption of metropolitan areas sustainable and to ensure through urban planning that land consumption does not increase in equal measure and arable land is spared - cities are often located in fertile river plains, on land that is also used for arable farming would be suitable. The other big challenge for urban planning will also be to prevent further growth of slums and to provide the residents with clean water, to dispose of sewage and waste hygienically and to improve the air quality. Cities then also offer opportunities for future development: The energy consumption per inhabitant in cities with dense housing, shorter distances and means of mass transportation is often much lower than the national average (one resident of New York produces two thirds of the carbon dioxide of an average American, one resident of São Paulo only a fifth of the average Brazilian). Access to health care and better education is easier, and city dwellers tend to want fewer children.

The power supply of the cities offers the best opportunities to use the waste heat generated by the generation of electricity in thermal power plants (>> here) for heating; however, small, decentralized power plants are more suitable for this than today's preferred large power plants (>> here). Due to the high energy density, exotic solutions are also available in cities; The Stockholm district of Hammarby Sjöstad recovers the heat from the wastewater via heat exchangers (>> here). The usability of geothermal energy by means of deep geothermal energy, on the other hand, varies greatly from city to city - depending on the geology. The direct generation of electricity by means of solar energy remains restricted due to limited (suitable) roof areas and that from large wind power plants due to a lack of acceptance by the population; A significant proportion of renewable electricity must come from the surrounding area in the future as well. Biogas could also be produced there, which drives the small combined heat and power plants (more on the topic >> Energy future).

In the meantime, high-rise buildings (>> more) and the first cities based on energy-efficient construction principles are already being built around the world: The settlement is being built in Abu Dhabi Masdarthat wants to combine the traditional design of Arab settlements with narrow streets and modern solar technology - the city should no longer need fossil fuels (>> mirror online); China is planning an eco-city in Dongtan before Shanghai (>> The most important principles that are applied in such houses and projects include the adaptation of the building to the local climate and the local conditions, optimal orientation to the sun and the use of new technologies, such as extremely effective vacuum insulation (>> more), passive ( >> more) or solar cooling systems (>> more)).

The dispute over development aid

The figures show that one of the most important causes of both hunger and disease is poverty. The 1.1 billion people who live on less than a dollar a day often go hungry and die much earlier than the rest of humanity. Extreme poverty, hunger and misery are a moral declaration of bankruptcy in a world in which there is enough food and enough resources to provide basic supplies for all people.

But what is the best way to fight hunger and misery? One way is represented by >> Jeffrey Sachs, head of the UN Millennium Project.For him, a large-scale and targeted public investment program can solve the whole problem by 2025. According to Sachs, US $ 160 billion per year would be needed, twice the current aid budget. If you add the costs for humanitarian projects such as tsunami aid around the Indian Ocean, 0.7 percent of the gross domestic product of the donor countries would be required. They have been promising this since 1980, but rarely keep it. The money should be invested in the systematic improvement of food production, nutrition, health and transportation.

The critics, above all the former World Bank employee >> William Easterly, consider this approach to be technocratic and fear that turnkey solutions such as those of the UN projects do not take enough account of the social structures, cultures and traditions of the regions - the result will be another major project, the fail. Worse: Such projects paralyzed initiative in the recipient countries and reinforce the idea that the rescue would have to come from outside. As a result, Sachs ’plan is only doubling the flow of funds into the pockets of corrupt local elites.

It is true that some rich people in poor countries prefer to invest their wealth abroad rather than in their own country - they must be made much more responsible. It is also true that rich countries often support corrupt regimes - but mostly not to help the poor, but because they own raw materials (>> The fight for raw materials). The discussion about the right development aid is important in order not to repeat mistakes. However, the contrast is by no means as strong as is often believed: Sachs also promotes agriculture and not major industrial projects, and Sachs also knows that his projects will fail without the involvement of local authorities.

Above all, we must not forget that our economic and trade policy (export of subsidized agricultural products, the prices of which destroy local markets; tariff barriers for developing countries; ...) contribute significantly to hunger and misery in the world. Development aid can only be effective if we change something here too.

Healthy food for everyone

See page >> The future of agriculture

A healthier world

One of the reasons for the population increase in the past was the >> successful fight against disease. Classic infectious diseases like typhus and cholera are now largely under control from a medical point of view thanks to vaccinations and antibiotics; but especially the poor still suffer from them. Malaria is still an undefeated disease in the tropics. Again, poverty reduction (as with hunger) is the most important factor; In particular, adequate nutrition for children must be a top priority. The Millennium Development Goals mentioned above also include basic medical care for the world's population, such as vaccinations for children. It must be worrying that resistance to antibiotics is increasingly developing, among other things due to the massive use of antibiotics in animal husbandry.

Medically, however, they are much more problematic than the classic infectious diseases novel, mostly due to a virus Infectious diseases. Man has hardly any defenses against this. The AIDS virus HIV has already caused a global catastrophe. Infectiologists currently fear an outbreak of bird flu - this can happen if a mutated virus appears that can be transmitted from person to person. Above all, prevention programs help against epidemics of such diseases; When diseases have broken out, it is then important to make the therapies accessible to poor people as well. But as the example of the eradication of smallpox shows, mankind is able to carry out such campaigns. In order to contain possible epidemics in good time, it is particularly necessary to set up global monitoring structures - consisting of laboratories that can detect novel pathogens.

Deadly encounters

Animals have always been carriers of disease; Infectious diseases transmitted from animals to humans are called Zoonoses. About 60 percent of all infectious diseases in humans originally come from animals; the most common is salmonella, influenza, plague and rabies are other examples. Over time, humans and pathogens often adapt to such an extent that the disease becomes less fatal. (The Europeans benefited from this adaptation when they conquered the world, >> more.)

The new types of infectious diseases usually also come from animals - the AIDS virus HIV is a modified form of the similar monkey virus SIV, the lung disease SARS is a modified cat virus, the Ebola virus is caused by fruit bats (a group of animals related to bats), which Avian flu transmitted by birds. One reason for the occurrence of these new types of infectious diseases is the ever more intensive contact between humans and wild animals, into whose habitat we are increasingly penetrating: In Africa, for example, monkeys, which are also infected with Ebola, are eaten as “bush meat” - and are eaten with it the virus is believed to be transmitted to humans. Elsewhere, factory farming promotes the spread of pathogens, such as avian flu, and of course intensive human travel encourages the spread of diseases as soon as they “manage” to be transmitted from person to person. Such “host changes” mean the danger of a zoonosis becoming a pandemic: For example, the virus that caused the “Spanish flu”, which killed at least 25 million people between 1918 and 1920, was a mutated bird flu virus.

While the classic infectious diseases are on the decline, take chronic diseases in importance. Many have to do with an unhealthy lifestyle - cigarette smoking, obesity and lack of exercise lead to cardiovascular and lung diseases. An unhealthy way of life can be placed in the area of ​​personal freedom - but smoking is more to be viewed as an addiction; restricting the advertising and sales of tobacco around the world would probably be the single most effective anti-chronic disease measure.

Chronic illnesses will become more common for another reason: Declining fertility also means that the average age of people is increasing - The world population >> is getting older. Instead of 672 million today, almost 2 billion people will be over 60 years old by 2050. The consequences of this development again depend on people's health, and this depends, among other things, on the level of education they have achieved - better educated people are generally healthier. In 2050, 80 percent of people over the age of 60 will live in developing countries, where today only families have to take care of people who are too old or sick to work - which is becoming increasingly poorer in view of increasing mobility. It is therefore essential that the age factor be included in the fight against poverty.

The number is increasing, especially in the emerging markets fatal accidents at work and job-related Diseases strong too; likewise take with increasing motorization traffic accidents as a cause of illness and death: in 2020 they could already be in third place. The remedial measures are obvious: enforcement of the minimum standards for occupational safety in the working world and training of road users as well as regular technical inspections of the vehicles.

Web tips

Population and Poverty Reduction

>> World Population Foundation: Lots of information and activities related to population growth and poverty reduction. The information sheets are a good introduction (


The City of Vienna's Urban Energy Efficiency Program shows how cities can reduce their energy consumption. >> Energiestadt Wien (an article from ZEIT).

Continue with:
>> Agriculture: Back to the Future

Back to:
>> Overview of future strategies

© Jürgen Paeger 2006 - 2019

Population in 2050 in million people:

1 India 1,639
2 China 1,402
3 Nigeria 401
4 U.S.A. 379
5 Pakistan 338
6 Indonesia 331
7 Brazil 229
8 Ethiopia 205
9 Congo 194
10 Bangladesh 193

according to UN World Population Prospects 2019, medium variant.

An example from Germany is the Freiburg district Vauban: An innovative energy and transport concept reduces the energy consumption of houses and enables many residents to do without a car. More: