... The Western Hemisphere is very sparsely populated by world standards--as is Australia. 75% of "crowded, suburban" California is in fact forest, desert and farmland, and the state feeds half of the U.S. population. The developed countries in the Americas could feed twice as many people as there are now. I ...
Not sustainably. For example, California, gets from rain and snow melt only half its water consumption - they "mine water" with ever deeper wells for the other half. Gravity sensitive satellites* have recently confirmed this. Private wells are going dry as the water table falls.
Yes, there has been a great migration for farms to the cities, in large part as small farmers can not compete with the giant agri-business, that plant and harvest from many square mile farms. The nitrogen fertilizer they use finds its way into the Mississippi and make larger algae blooms every year, that then die off leaving every larger Oxygen free zones - no fish or shrimp, etc. US education system for the masses, with local funding of schools, is failing many - they can't find a job as lack the skills needed. 1 in 6 Americans now needs financial support (or at least is collecting) from the tax payers in part, but also just part of the ~1 trillion / year growing US debt. Is the rapidly increasing per capita US debt now sustaining the economy, sustainable?
From visit to USdebtclock.org a minute ago: Each US, citizen, (me in Brazil included) is 56,487 dollars in debt (national debt / population) or in dollars: 146,302.35/ household and growing faster than purchasing power of salaries, except for the top 2 or 3%. Per tax payer (me included) it is $145,049 - Sustainable?
BTW, from
http://www.usadebtclock.com/ you can see that the US's currently unfunded liabilities (a "present" for our children and theirs) is 6.82 times greater than the current debt but that can change by congressional action, assuming Congress can still act instead of only point fingers of blame at other members. Obama's tax reform plan (help the middle class with very rich and corporations, paying more) to be major part of the "State of the Union" speech, is DOA with Republicans in control of Congress. Worse: the fight will mean not even what they could agree on will get done.
It is things like this that make me say "unstainable" but I hope you are correct and I am wrong. I also hope current cheap oil soon ends - it is dealing a "body blow" to efforts to switch to a sustainable energy systems. Many years ago I read that the cost of an Idaho potato eaten in NYC was 95% due to oil - and that was back when oil was half or less the cheap price it is today. Oil is used for plowing, planting, fertilizing, harvesting, cross country transport, local distribution, and cooking (directly or indirectly) to name the major inputs of a potato. Do you assume either oil is inexhaustible or has affordable alternatives, so this is all sustainable?
* I'm almost sure they are a pair, one following the other by dozen or so miles. That way their dynamic changes in separation gives data that can be "unfolded" to give high resolution information on the mass below. By comparing this years data to last year's etc. they can quantatively measure the mining of the water (all over the SW, not just California.) Just one more fact confirming we can not even sustain what we are currently doing.
Then in addition to your share for the US's debt there is your personal debt:
but if instead of "by accounts" it is averaged over all Americans, the numbers are a little bit lower, except mortgage debt is 30% lower as many don't have one. Interesting to note that student loan debt is greater than all other debt's totaled, when mortgage debt is excluded from the total. Also total of the four debts of graph is 144,284 dollars so is just slightly less than the average household's share of the US debt. I think Amerians have been reducing their personal debt for several year but their share of US debt keeps climbing.
This data from and more discussion at:
http://www.fool.com/investing/gener...e-american-has-this-much-debt-how-do-you.aspx