ABUL RIZVI: Using immigration to manage Australia's ageing population Independent Australia 03 May 2021, 16:52 GMT+10 For developed nations, the period 1950 to 2050 will be an extraordinary population shock, tracking the four stages of the boomer life cycle: childhood, adulthood, old age and death. Nations will move through these four stages in different timeframes, depending on their rate of net migration and when they transitioned to below replacement fertility of less than two births per woman. Continental Europe and Japan entered the old age stage - that is their working age to population ratio went into decline - from around 1990, but it wasn't until 2010 that all developed nations, plus China and Russia, entered this stage. Nations with high net migration such as Australia will move through the stages more gradually than nations with low or negative migration.