A new study, published this week in The Lancet, concludes that the global population is likely to peak in 2064 at 9.7 billion and fall to 8.8 billion by century’s end. The report foresees major shifts in geopolitical power – producing a more multi-polar world – with 23 countries seeing their populations shrink by more than half as a result of declining fertility rates. Liberal immigration policies could help to maintain population sizes and economic growth, the authors suggest.