Context

• The Lancet medical journal published a study that projects population trends for the rest of this century, titled ‘Fertility, mortality, migration, and population scenarios for 195 countries and territories from 2017 to 2100: A forecasting analysis for the Global Burden of Disease Study’.
• It used data from the Global Burden of Disease Study, 2017, to model future population in various scenarios as a function of fertility, migration, and mortality rates.

Key Findings of the Study:

• For India, the study predicts a peak population of 1.6 billion, or 160 crores, in 2048, up from 1.38 billion (138 crore) in 2017.
• However, it goes on to state that though India will be the world’s most populous country in 2100, its population is set to decline to 1.09 billion, or 109 crore, a drop of 32 per cent from the projection for 2048.
• India’s Total Fertility Rate (the average number of children born to each woman) could decline steeply to 1.29 by 2100 from 2.14 in 2017, which itself was a far-cry from 5.6 in 1950.
• The analysis projects world population to peak at 9.73 billion in 2064, and decline to 8.79 billion in 2100.
• It says 23 countries, including Japan, Thailand, Italy and Spain, are likely to witness their populations shrink by more than 50 per cent.
• The study also projects that 183 of the 195 countries will have TFRs below the replacement level of 2.1 births per woman.
• Replacement level is the level of fertility needed at which a population exactly replaces itself from one generation to the next.
• The global TFR is predicted to steadily decline from 2.37 in 2017 to 1.66 in 2100.
• The study also predicts huge shifts in the global age structure, with an estimated 2.37 billion individuals over 65 years of age in 2100, compared to 1.7 billion under 20. 
• The number of working-age adults (20-64 years) in India is expected to decline to about 580 million in 2100 from 762 million in 2017.
• However, even the reduced number will be the largest working-age population in the world, followed by Nigeria, China and the US.
• China’s working-age population could also decline to 357 million from 950 million, and according to the researchers, this trend could hamper economic growth and lead to global power shifts.
• From 2017 to 2100 India is projected to rise up the rankings of countries with the largest total gross domestic product (GDP) globally from 7th to 3rd.
• India is also forecasted to have the second largest net immigration in 2100, with an estimated half a million more people immigrating to India in 2100 than emigrating out.

Source: Lancet Report, The Hindu, Indian Express