Instead, many in the troubled south are carving out a simple existence for themselves in a new European reality. They must decide whether to stay home, with the protection of family but a dearth of jobs. Or they can travel to Europe’s north, where work is possible to find but where they are likely to be treated as outsiders. There, young people say, they compete for low-paying, temporary jobs but are sometimes excluded from the cocoon of full employment.

For the European Union, addressing the issue has become a political as well as an economic challenge at a time of expanding populist discontent with the leadership in Brussels and national capitals.

Chancellor Angela Merkel of Germany has called youth unemployment “perhaps the most pressing problem facing Europe.” Ms. Merkel flew to Paris on Tuesday to join other European leaders at a special youth unemployment summit meeting called by President François Hollande of France. Governments renewed a pledge for an employment-promotion program worth 6 billion euros (about $8 billion) starting next year.

But economists said the program by itself was unlikely to put more than a bandage on a gaping wound. For members of the generation that came of age since the financial storm of 2008, promises of future aid and future growth only highlight questions about when, or whether, they will be able to make up for the lost years.

“We hope 2014 will be a year of recovery,” said Stefano Scarpetta, the director of employment, labor and social affairs at the Organization for Economic Cooperation and Development. “But we are still looking at a very large number of youth who will have endured a long period of extreme difficulty. This will have a long-lasting effect on an entire generation.”

A Job, but Far From Home

Soon after her 23rd birthday four years ago, Melissa Abadía made a wrenching decision: She would leave her close-knit family in Spain, where the grinding fallout from the 2008 financial crisis had made securing a good job impossible, and move to the Netherlands, where employers were still hiring.

“When I got on the plane, I was crying,” Ms. Abadía, a bright, ebullient woman, recalled. “But I had to decide: Should I fight for something back home that makes no sense, or get out of there and make a life for myself?”