Does this even matter ? "Average" income hasn't been growing now in America for about a decade. If you look closely there are 2 factors at play :

1) increase in population 2) stagnant (not decreasing) wages (even inflation adjusted it's a tossup at this point)

Combined these lead to decreasing average wages. Not all that many people have really lost income, but there are more people for the same jobs, so many people have lost jobs entirely. There are more people with essentially zero income.

The easy solution, stopping 1) from happening (immigration controls, population controls, ...) won't work due to massive state obligations (some inflation-adjusted to make matters worse) to the soon-to-be-pensioned. It's even impossible to stop immigration and replace it by increased fertility because increased fertility is a net-cost to society until 20 years pass.

Even putting aside the morality questions, (almost) stopping immigration might have worked 10-15 years ago, but today, it seems it will make matters worse, not better.

Worldwide the situation is even more striking :

1) massive rise in average incomes (factors, 2,3,4 depending on how far you go back) 2) more massive rise in population (let's say about 1.5*income rise)

For close to the last 4 decades, 2 has outstripped 1 to the point that a lot of people are claiming that we are within 10% of the planet's carrying capacity with abundant energy sources (read : cheap oil).

Jee, I sure hope nothing happens to that cheap oil ... Oops.

Very funny way to make the point, if you realize that this problem has nothing to do with America, beyond the idea that America is somehow supposed to solve it : http://www.thedailyshow.com/watch/wed-june-16-2010/an-energy...

Unfortunately renewable energy suffers from the reverse problem of immigration : right now, we have renewable energy with a EROI factors of 2-3 over a period of 2-3 decades. That means that for the first 10 years renewable energy INCREASES our dependance on fossil fuels. The only energy type that doesn't suffer this problem is nuclear energy, and it has other problems.