Millennials have been blamed for killing all sorts of things in America: breakfast cereal, starter homes, beer. Now it looks like retirement is likely to be next on the chopping block.

In order to retire by 65, the traditional retirement age for older generations, millennials have to squirrel away more than 40 percent of their income over the next three decades. That's according to Olivia S. Mitchell, an economics professor at Wharton’s Pension Research Council at the University of Pennsylvania who specializes in insurance and risk management. Using academic research from an economist at MIT, Mitchell found that the traditional advice of saving 15 percent of income falls far short of what most millennials will need when they retire. That aside, the average millennials are saving is only about 6 percent of their income for retirement.

Millennials' ability to save at rates at or above previous generations is contingent on a variety of greater forces. Many graduated into one of the worst recessions in recent history, but much of the current economic situation arose from longer-term trends. According to the Economic Policy Institute, up until the ’80s, productivity and wages grew at the same pace, meaning that workers' paychecks increased as businesses' profits rose. That came to an abrupt halt in 1979, and since then productivity has increased 69 percent while hourly compensation has only inched up 11 percent. So people are making more money for their employers than ever before, but the employers are pocketing almost the entire increase.

And that 11 percent increase in hourly compensation hasn't kept up with inflation, which has risen 211 percent since 1980. In roughly that same time period, the cost of food rose by 244 percent, and health-care costs went up 601 percent. The cost of college has increased at the most unhinged pace, skyrocketing 1,120 percent since 1978. And as Yale political science professor Jacob S. Baker writes in The Great Risk Shift: The New Economic Insecurity and the Decline of the American Dream, retirement has become increasingly out of reach for Americans as businesses move from offering pensions to less reliable 401(k)s instead.

No one age group is making out particularly well in the face of those economic stressors, but millennials are hit particularly hard. The credit-reporting company Experian found that consumers in their 30s have the heaviest student debt loads, with 35-year-olds topping out at an average of $42,564 per person. And while people in their 20s have relatively smaller debt loads, the 18-to-29 age group has the biggest proportion of those carrying debt by far, with a staggering 34 percent according to a recent Pew Research Center survey. By and large, millennials have a lot less money and stable prospects than their parents' generation. But it's not exactly sunny for older generations either: Bankruptcy rates among Americans 65 and older are three times as high as they were in 1991. Meaning many millennials may not only have to cope with their own limited financial resources but also grapple with how to provide for aging family members.

On the upside, millennials may not have to worry as much about retirement as earlier generations did—after rising steadily for nearly a century, Americans' life expectancy has dropped twice in just three years. And there's always the possibility that looming climate disaster will cut retirement short also.