CBO: federal budget is on an unsustainable path

An "unsustainable path" means that if something isn't done, trends just go off the chart. Here is the discussion from CBO:

Under current law, the federal budget is on an unsustainable path, because federal debt will continue to grow much faster than the economy over the long run. Although great uncertainty surrounds long-term fiscal projections, rising costs for health care and the aging of the population will cause federal spending to increase rapidly under any plausible scenario for current law. Unless revenues increase just as rapidly, the rise in spending will produce growing budget deficits. Large budget deficits would reduce national saving, leading to more borrowing from abroad and less domestic investment, which in turn would depress economic growth in the United States. Over time, accumulating debt would cause substantial harm to the economy. The following chart shows our projection of federal debt relative to GDP under the two scenarios we modeled.

Keeping deficits and debt from reaching these levels would require increasing revenues significantly as a share of GDP, decreasing projected spending sharply, or some combination of the two. . . . .