CBO Director Douglas Elmendorf is no stranger to adding up the cost of congressional schemes. In February, the CBO outlined some of the costs imposed on the nation by ObamaCare, which turns four on Sunday. Less work and more federal spending about sums it up. Elmendorf had fresh warnings this week, saying we just can’t pay for all this massive government expansion: “So we have a choice as a society to either scale back those programs relative to what is promised under current law; or to raise tax revenue above its historical average to pay for the expansion of those programs; or to cut back on all other spending even more sharply than we already are.” The challenge isn’t so much annual deficits, he said, as “the very high level of debt” over the long term. Call it what we’ve been calling it all along: A debt bomb.