World Population Day: How is the population changing

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Published 4 months ago

Today, the world is celebrating 50 years since the International Conference of Human Rights took place in 1968, when for the first time, family planning was recognised as a human right. Thus, on World Population Day, looks into the state of the world’s population to better understand the implications on the environment, gender equality, and wealth distribution. Find out whether your host country is home to megacities, a rapidly growing population, or an ageing population.

The most populous countries

China busy street
TonyV3112 /

Currently, we are seven and a half billion people on Earth — a number which is estimated to increase per almost two billion by 2050 according to the latest UN report. Even though, in general, fertility levels are dropping, the world’s annual population is growing by around 83 million people. These numbers are vital for governments and organisations which are trying to set development goals.  

China (1.4 billion), India (1.3 billion), and the United States (329 million) are the most populous countries in the world, followed by Indonesia (264 million) and Brazil (209 million). China and India alone comprise 37% of the total global population.

From the African continent, Nigeria is the most populous country (and the seventh most populous in the world) with about 195 million inhabitants. It is estimated that Nigeria’s population will surpass America’s, and by 2050 will become the third largest in the world. Also, in the next 30 years, the population of 26 African countries is expected to double.

According to reports and evaluations, two-fourth of the world’s population will be concentrated in no more than nine countries, including the Democratic Republic of the Congo, Pakistan, Ethiopia, the United Republic of Tanzania, and Uganda.

Fertility and ageing population

Indian old woman
OlegD /

Fertility is in decline, and even in Africa — the continent with the highest levels — fertility has dropped from 5.1 births per woman in 2000-2005 to 4.7 births in 2010-2015. However, surprisingly, Europe is following a different route, with fertility increasing from 1.4 births to 1.6 during the same periods.

But the reduction in fertility levels doesn’t only result in slower population growth; it also means that the number of older inhabitants is increasing. Precisely, by 2100 the world is expected to have three times more people who are aged 60 or above than it has today. Thus, from 962 million in 2017, retirees are estimated to reach 3.1 billion in 2100. Currently, 25% of Europe’s population and 5% of Africa’s is at the age of 60 or above. Such an increase in the ageing population has a severe impact on the countries’ healthcare systems, social protection, and pension schemes.

At the same time, life expectancy at birth has risen globally from 65 years for men to 69 and from 69 years for women to 73. However, there are significant disparities across regions, countries, and income groups.

Urbanisation and megacities


Socio-economic reasons such as quality of life, career opportunities, and salary draw large populations towards urban areas. Urbanisation leads to the speedy creation of megacities, which are cities with ten million citizens or more. In 1975, only three cities (Tokyo, New York, and Mexico City) had more than ten million residents. Today, seven per cent of the world’s population lives in the 31 existing megacities, and by 2030 the number of urban citizens is estimated to become almost nine per cent spread in 41 megacities.

Tokyo in Japan is the largest city in the world with 38 million residents, and New Delhi in India is the second largest with about 26 million residents, followed by Shanghai (24 million), Mumbai (21 million), Sao Paulo (21 million), and Beijing (21 million). Even if UN’s estimates about Tokyo’s one million decrease in population by 2030 are proven to be correct, Tokyo will remain the top megacity in the world.

Among the challenges that the increasing populations in cities must face is the housing shortage; according to a McKinsey report, by 2025 1.6 billion people could struggle to find decent and at the same time affordable housing, which doesn’t exceed the 30% of their income. Also, quality of life in megacities is decreasing due to lower income, lack of resources, and high levels of pollution.

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