Four years of relentless austerity in many of the euro zone’s most debt-hobbled countries have forced many of their youngest and sometimes brightest workers to grab the plane, train or boat and emigrate in search of work. For countries with a long history of emigration, such as Ireland, this is depressingly familar — coming just 20 years after the country’s last debt crisis and national belt-tightening in the 1980s crescendoed, with the exit of some 40,ooo a year in 1989/90 from a population of just 3-1/2 million people.

The intervening boom years surrounding the creation and infancy of the Europe’s single currency and expansion of the European Union eastwards saw huge net migration inflows back into the then-thriving euro zone periphery¬† — Ireland, Greece, Portugal, Spain and Italy — and created a virtuous circle of rising workforces, higher demand for housing/goods and rising exchequer tax receipts.

But all that has gone into reverse again since the credit, property and banking crash of 2008.

While the exodus takes short-term pressure off dole queues and national welfare bills, there is growing concern that the timing of this latest wave of young worker emigration comes as underlying societies are ageing, dependency ratios are rising and longer-term pressure on government finances from pension commitments is set to grow.

In a note to clients on Tuesday, Citi economist Michael Saunders details the extent of the renewed migration from the periphery and reckons prolonged austerity is exaggerating the shift and damage to the long-term financial sustainability of these countries’ already battered finances. With Europe’s impending pension shortfalls, he argues, they need higher working populations, not smaller ones.