A leading economist predicts there will be at least 5 million potential job vacancies nationwide within the next decade, and more jobs than people to fill them by 2018.

Barry Bluestone, dean of the School of Public Policy and Urban Affairs at Northeastern University, predicts nearly half of the jobs (2.4 million) will be in the social sector, including education, health care, government and nonprofit organizations.

The loss in total output could limit the growth of needed services and cost the economy as much as $3 trillion over the five-year period beginning in 2018.

"If the baby boom generation retires from the labor force at the same rate and age as current older workers, the baby bust generation that follows will likely be too small to fill many of the projected new jobs," according to a new report by Bluestone.

Bluestone’s research is one of four papers written by independent experts and released by MetLife Foundation and Civic Ventures, a think tank on boomers, work and social purpose.

Bluestone’s analysis builds on the 2008 MetLife Foundation/Civic Ventures Encore Career Survey conducted by Peter D. Hart and Assoc., which shows most people expect to work longer than previous generations, but half of those age 44 to 70 want "encore" careers that combine personal meaning, continued income and social impact.

"Not only will there be jobs for these experienced workers to fill," Bluestone writes, "but the nation will absolutely need older workers to step up and take them."

The research identifies 15 jobs that will provide the largest number of potential new career opportunities in the coming decade. The list is dominated by seven job categories in health care, others in nonprofits and government and clergy and social and human service assistants.

"This research makes it clear that interest in encore careers can help solve long-standing social problems and an anticipated labor gap," said Dennis White, president and CEO of MetLife Foundation. "It’s time to think creatively about how to encourage and make use of this growing source of human talent."