The Institute for Health Metrics and Evaluation at the University of Washington in Seattle is one of the leading locations for the study of population dynamics. A recent large-scale model of global population that has emerged from the institute has now been published by The Lancet journal, and it reflects a substantially altered conventional wisdom about when global population will peak and at what level. Some of the differing results of the new model come from the choice to use “completed cohort fertility at 50 years” — in other words, the mean of the number of births per female aged 50. This is, the scientists argue, a more stable and, therefore, usable variable than the standard “total fertility rate”, or TFR. Two other important variables that were considered and which impacted the results were educational attainment and the availability of desired contraceptive mechanisms. These meant that the pace of change of cohort fertility in effect intensified as education and access to contraception
The model concludes that the global population will in fact peak in 2064, at 9.73 billion people, and then begin to decline, ending the century at 8.79 billion. India, in particular, would end the century as the largest country by population, at 1.09 billion people, followed not by China but by Nigeria at 791 million. China would instead be third, followed by the United States and then Pakistan at 248 million people. The model predicts almost 600 million fewer people in South Asia in 2100 than is the hitherto generally accepted number from the United Nations Development Programme. The scientists expect that India dipped below the replacement rate of fertility in 2018, and it would continue to decline steeply till 2040, when it would reach a TFR of 1.29 — equivalent to the TFR of the European Union countries with the lowest fertility. The number of working-age adults would thus peak in India at around 2050, at almost 1.2 billion; in spite of steep declines thereafter, India would end the century with the largest working-age population. However, once the modellers included migration in their scenarios, their predictions for GDP were counter-intuitive: China would become the world’s largest economy in 2035, but then by the end of the century would be replaced once again by the United States, the latter’s economy driven by the engine of immigration.
Policymakers have to carefully consider the implications of this model. Several aspects of long-term growth and development are implicated by it. First, it is clear that the period between 2020 and 2040 is essentially India’s great population boom; the children being born or who are in school today are those the country will have to depend on if it is to reach some level of prosperity. If this generation’s human capital is not prioritised, then India will grow old before it grows rich. The second concern is that India must prepare for the social implications of declining fertility. Some areas within the country will begin to shrink before others — they will need to be accepting of migration, as well as net providers of capital to the rest of the economy. Finally, women’s rights and reproductive advances will be under threat as conservative elements in society react negatively to the decline in fertility. They will have to be protected against political backlash.