Sarah Harper: Long lives and low birth rates are a problem across the West

The EU is likely to see an average increase of 23 per cent in public pension expenditure by the middle of the century

Dramatic and continuous falls in births combined with ever lengthening lives are leading to continual upward shifts in the age structure of the Japanese population. Yet, while Japan may be leading the way, it is by no means alone. Most countries now have total fertility rates, or the expected number of children born per woman, below or approaching replacement. Many South-east Asian nations are now lower than the UK, while Hong Kong is now producing less than one child per woman. Longevity is also increasing, with life expectancies at birth reaching 80 for women in Europe and North America.

It is the effect of declining births combined with lengthening lives which is causing challenges for our economic and social systems. At a time when longevity is requiring increased investment in long-term care and pensions, the number of younger workers and caregivers is falling. Despite recent reforms, the EU is likely to see an average increase of 23 per cent in public pension expenditure by the middle of the century.

There is already considerable evidence that these shifts are having an impact at earlier ages. Analysis of housing construction in the OECD, for example, has identified a strong correlation with the shift in the population from younger to mid-life and older ages, with a corresponding downward trend in builds.

The pressures are likely to be greatest in Asia and Latin America. Europe has had more than 100 years to adapt to these trends. Most developing economies will have but one generation, as their shift from predominantly young to predominantly old societies will take only around 25 years.

The author is professor of gerontology and director of the Oxford Institute of Population Ageing, University of Oxford