Krugman: This is not a crisis. It’s not even a picture of a crisis.

[n2doc]

7. Because governments can make radical changes

Like war, or massive tax breaks, or even tax increases. And the underlying economy also makes huge changes. For example, if the economy were to grow at 3 % over the next decade, the issue of social security 'insolvency' would be moved back to the end of the century. Without any other policy changes.

Climate change estimates recognize that there are big year-to-year differences that can't be modeled. And even their models are run with several assumptions of how CO2 inputs will change, yielding very different warming curves. Because we don't know if or when the world will pull its collective head out of its collective ass and start to really take the problem seriously. It will take much more than solar farms in Germany.

You might look at the history of government funding. Many programs have seen effective cuts. Only the military, domestic spying/security, and the Big entitlement programs have seen increases. No one in DC seems to want to cut the military or spying. But a program like ARPA-E, which funds energy research, is slated for an 80% cut because the repubs don't like it.