Experts have been predicting it, well, for generations now: that the upcoming generation may be the first to experience a lower standard of living than its preceding generation. Now, a comprehensive global study of economic and demographic trends argues that this time it could really happen.

The forecast comes from consulting giant Accenture. The company commissioned a study that crunched considerable data related to world population patterns, economic shifts and workforce trends. Its conclusion: By 2030, the U.S. standard of living could decline by as much as 9 percent, dropping it back to the 2000 level.

"For the first time in our nation's history, the next generation may not be better off than their parents," said Peter Hutchinson, who leads Accenture's public service strategy for North America state, provincial and local business. "For decades people have come to expect our economy and way of life to continue to improve, not decline. Our standard of living hinges on harnessing a skilled workforce to power our economies."