WASHINGTON -

The college class of 2012 is in for a rude welcome to the world of work.

A weak labor market already has left half of young college graduates either jobless or underemployed in positions that don't fully use their skills and knowledge.

Young adults with bachelor's degrees are increasingly scraping by in lower-wage jobs - waiter or waitress, bartender, retail clerk or receptionist, for example - and that's confounding their hopes that a degree would pay off despite higher tuition and mounting student loans.

While there's strong demand in science, education and health fields, arts and humanities flounder. Median wages for those with bachelor's degrees are down from 2000, hit by technological changes that are eliminating midlevel jobs such as bank tellers. Most future job openings are projected to be in lower-skilled positions such as home-health aides, who can provide personalized attention as the U.S. population ages.

Last year about 1.5 million, or 53.6 percent, of bachelor's-degree holders 25 and younger were jobless or underemployed, the highest share in at least 11 years. In 2000, the share was at a low of 41 percent, before the dot-com bust erased job gains for college graduates in the telecommunications and Internet-technology fields.

According to government projections released last month, only three of the 30 occupations with the largest projected number of job openings by 2020 will require a bachelor's degree or higher to fill the position - teachers, college professors and accountants. Most job openings are in professions such as retail sales, fast food and truck driving, jobs that aren't easily replaced by computers.