In Germany, for example, where 20% of the population is older than 65, the number of working-age adults will shrink from about 50 million today to as few as 34 million by 2060. Among emerging markets, rapidly rising life expectancy and plunging fertility are likely to double the share of China’s over-60 population by 2050 – adding roughly a half-billion people who require support in their unproductive years.