That's the bipartisan Committee for a Responsible Federal Budget commenting on the 2014 CBO long-term budget outlook. (You can try to balance the budget with their nice budget simulator.)
Related: Clifford Asness, "We Must Head Off the Looming Pension Tsunami".
We have not saved enough for the retirements that we have promised people, public or private. Moreover, that problem is greatly understated by current reporting methods. This may seem an undramatic candidate for addressing one of our biggest problems, but that's part of my point. Unlike hurricanes or wars or debt ceilings, we don't have to deal with retirement funding today. However, this problem grows and eventually will metastasize. Until the looming pension crisis is dealt with, one way or another, no one's retirement is secure, no government fiscal projections are fully credible, and no one's property is safe against extreme and unpredictable taxation.