As if the world did not have enough on its plate from the global recession and the pandemic , another unseen crisis could be creeping up on us with grave, long-term consequences. Birth rates around the world are declining at an alarming rate, with major implications for future growth, prosperity and social stability. Falling birth rates could mean many countries around the world face smaller populations by the end of the century. There are many factors, but fear of the future could be a major reason parents are choosing to postpone or not have children at all right now. The Covid-19 crisis could be the antithesis of the baby boom phenomenon which helped catapult the global economy into a new era of post-war growth and prosperity. Policymakers cannot afford to ignore the consequences. Once, we used to fret about global population growth running out of control and outpacing the planet’s resources. Now the worry is that population growth is slowing down too fast and, with people generally living longer, there are new problems to contend with. The world may be transitioning towards population decline, but it’s also a major success story. Falling birth rates around the world reflect greater female emancipation. More women are in work and in education, enjoying better welfare, rising affluence and improved contraception. There is a long way to go, but as opportunities improve for women it means the global birth rate will continue to decline. The global fertility rate – the average number of children a woman gives birth to in her reproductive years – is falling at a worrying rate. According to researchers at the University of Washington’s Institute for Health Metrics and Evaluation, it has more than halved from an average of 5 births per woman in 1960 to 2.4 in 2018 and is forecast to fall even further, possibly as low as 1.52 by 2100. If the global birth rate falls below 2.1, it is considered the approximate point when world population growth goes into reverse. Major nations including Japan, Italy, Spain and South Korea could see their populations more than halve by the end of the century. With people generally living longer, the impact could be dramatic with fewer economically active young people supporting an increasingly older society. China, currently the world’s most populous nation, could see its population peak at 1.4 billion in four years’ time before nearly halving to 732 million by 2100. The total number of people on the planet could peak at 9.7 billion around 2064 before dropping to 8.8 billion by the end of the century, posing major challenges for economic planners. Optimists might think it’s a good thing with more resources to be distributed among fewer people, but it’s far outweighed by the downside risks. To maintain global growth around the optimal 3 to 4 per cent mark, more workers will be needed to build future factories, run the machines, market the output and provide frontline services to keep the global economy working at full strength. More importantly, in a world with fewer economically active workers, who’s going to mop up all the final demand? There is a limit to how much technology, enterprise and spending power can fill the potential gaps in aggregate supply and demand in future. Increased use of artificial intelligence and robotics might bridge some of shortfalls in the supply chain, but it is not the answer. The propensity to spend is zero for algorithms and machines. Economies such as the United States and China need bigger workforces and more consumers to strengthen domestic demand. It is the staple diet of modern, consumer-driven economies. A vibrant, optimistic population is vital to healthy growth in retail sales, housing, travel, financial services and consumer spending power, which is needed to sustain economic demand. The pandemic has badly damaged economic confidence at all levels. Governments need to think carefully about the long-term effects on family perceptions and the willingness to bring children into an uncertain world. Future monetary and fiscal incentives must be attuned to rebuilding the right conditions and incentives for sustainable global population growth ahead. Growing economies need more people in work, or else human progress could be in grave danger. David Brown is the chief executive of New View Economics