The past century has seen an exponential rise in global population. It took 123 years for the world population to grow from 1 to 2 billion (in 1927); 33 years to reach 3 billion in 1960; and only 39 years to double to 6 billion in 1999. Growth, however, slowed to 1.0% in 2020 and global population is now predicted to peak at 9 billion in the 2050s.
This is from The End of Population Growth – Sanjeev Sanyal – Project Syndicate:
What demographers call the Total Fertility Rate is the average number of live births per woman over her lifetime. In the long run, a population is said to be stable if the TFR is at the replacement rate, which is a little above 2.3 for the world as a whole, and somewhat lower, at 2.1, for developed countries, reflecting their lower infant-mortality rates.
The TFR for most developed countries now stands well below replacement levels. The OECD average is at around 1.74, but some countries, including Germany and Japan, produce less than 1.4 children per woman. However, the biggest TFR declines in recent years have been in developing countries. The TFR in China and India was 6.1 and 5.9, respectively, in 1950. It now stands at 1.8 in China, owing to the aggressive one-child policy, while rapid urbanization and changing social attitudes have brought down India’s TFR to 2.6.
…. it is likely that world population will peak at nine billion in the 2050’s, a half-century sooner than generally anticipated….
Food scarcity
We are likely to face increasing scarcity of food and water. Advances in technology have improved crop yields, but increased meat consumption in China and other Asian economies will reduce overall output. The area of land required to produce an equivalent amount of edible protein from livestock is 4 to 5 times higher compared to traditional grains and legumes, and up to 10 times higher for beef. Diversion of land use for ethanol production may also restrict food output.
Global warming, whether man-made or a natural cycle, may also contribute to declining food production — through droughts, floods and depleted fish stocks.
Ageing populations
Populations in most developed countries are ageing due to low birth rates and the baby boom after World War II. This is best illustrated by the growing percentages of population aged 65 and over.
China is experiencing a similar ageing population as a result of its one-child policy.
Ageing populations are likely to increase demand for health services, retirement accommodation, and investment services.
Growing populations in under-developed countries
South Asia has experienced massive population growth over the past 50 years but that growth is now slowing. Sub-Saharan Africa, however, continues to grow.
Migration
Of 417,000 first-time applicants to the EU, the top nationalities are mainly from conflict areas (Syria, Afghanistan), political strife (Venezuela, Colombia, Iraq) or for economic reasons (struggling economies).
Migrants are increasingly being used as a political weapon: to heighten political divisions by stoking a nationalist backlash against rising immigration. The latest is attempts by Belarussian dictator Alexander Lukashenko to fuel a migrant crisis in Lithuania and Poland by flying in migrants and assisting them in crossing the border illegally.