How can countries deal with falling birth rates?

Prof Lee’s thoughts may not be very popular with many people, but economically it looks inevitable. As life expectancy increases it becomes increasingly difficult to afford ever longer retirements. Something has to give, and working longer is the obvious solution.

There is, however, another answer to this problem, as Prof Harper makes clear – increased immigration. Yet this is obviously a hot political potato on both sides of the Atlantic.

“Migration could easily solve the problem of lower birth rates from a demographic point of view,” she says. “There are political and policy issues, but demographically what we should be doing is allowing those countries with huge child-bearing rates, and with huge numbers of workers for maybe the next four decades, to be able to flow across the world and make up the slack.”

We all know there are huge pressures against large-scale immigration, although even populist regimes often turn a blind eye to it when necessary.

Elizabeth Kuiper, associate director of the European Policy Centre think tank, says Hungary is a case in point. Its government claims to have a zero-tolerance attitude to migrants, but “we know that while these countries will not admit it publicly, in sectors like care and health care they have developed unspoken strategies for selective migration”.