Although most of today’s retirees are financially secure, they may be living in a golden age that baby boomers and generation Xers largely won’t enjoy when they quit working, researchers say.

Longer retirements and declines in retirement incomes as a percent of preretirement earnings will mean less comfortable retirements for many Americans, the Center for Retirement Research at Boston College says.

The CRR developed a National Retirement Risk Index to measure the share of working-age households at risk of being unable to maintain their preretirement standard of living after they leave work.

That index shows that, even if people retire at age 65 and annuitize all their household wealth–including receiving reverse mortgages on their homes–43% will be at risk of having inadequate retirement income.

For early boomers, born from 1946 through 1954, 35% of all households are at risk–that is, likely to have retirement income more than 10% below the target needed to maintain their preretirement living standard, according to CRR. The at-risk share rises to 44% for the late boomers (1955-1964) and 49% for members of Generation X (1965-1972).

One-earner couples, who receive more generous Social Security benefits, are less likely than two-earner couples to be at risk, while single women are more likely to be at risk than single men, the researchers pointed out.

The research team concluded the situation is not hopeless.

For instance, “if people choose to work longer–even just 2 years–and save 3% more, they substantially can improve the outlook for their retirement security,” the study report concluded.

Nationwide Financial Services Inc., Columbus, Ohio, which helped fund the study, issued a statement supporting the use of the index to gauge Americans’ ability to enjoy a decent retirement.

“For the past decade, we have heard qualitatively that the retirement outlook for Americans is troubling,” said Mark Thresher, president of Nationwide Financial. “Now, the risk is quantified by a respected source. It is time we use tools such as the index to inform and spur needed debate on policies that can improve the retirement outlook for Americans.”