The study, which was conducted by researchers from the Institute for Health Metrics and Evaluation (IHME) at the University of Washington’s School of Medicine, used models to predict that the world population will likely peak in 2064 at around 9.7 billion, before declining to 8.8 billion by 2100. The research indicates that by the end of the century, projected fertility rates in 183 of 195 countries will not be high enough to maintain current populations “without liberal immigration policies.“ae0fcc31ae342fd3a1346ebb1f342fcb “Responding to population decline is likely to become an overriding policy concern in many nations, but must not compromise efforts to enhance women’s reproductive health or progress on women’s rights,” Stein Emil Vollset, MD, lead author of the study and IHME professor, said in a statement. Vollset added that the “findings suggest that the decline in the numbers of working-age adults alone will reduce GDP growth rates that could result in major shifts in global economic power by the century’s end.” Richard Horton, MD, editor-in-chief of the journal The Lancet, which published the study, said the findings had profound implications not only on planning for the future, but also in terms of outlining and protecting the very policies that make progress possible. “[This study] offers a vision for radical shifts in geopolitical power, challenges myths about immigration, and underlines the importance of protecting and strengthening the sexual and reproductive rights of women,” he said in a statement. Horton added that, according to the study, “the 21st century will see a revolution in the story of our human civilization. Africa and the Arab World will shape our future, while Europe and Asia will recede in their influence. By the end of the century, the world will be multipolar, with India, Nigeria, China, and the U.S. the dominant powers. This will truly be a new world, one we should be preparing for today.” RELATED: For more up-to-date information, sign up for our daily newsletter. The study notably contradicts the findings of a report released in June 2019 by the United Nations, which claims that the world population won’t shrink but will instead continue to rise to 11 billion by the year 2100. But despite the competing models disagreeing on overall reproduction rates, the UN’s report also finds that an increase in average age and overall population size will put stress on the global economy. And for more on what may be in store for humanity, check out 25 Things That Would Happen to the Planet If the Population Keeps Growing.