Permabyte: Can Permaculture Feed the World?

Because of the work of various Master Gardeners in the United States, Steve Solomon and his book Gardening When it Counts, Peter Bane's plan in The Permaculture Handbook for garden farming, and John Jeavons Bio-Intensive gardening. All of these indicate that it is possible to grow all of the food necessary to properly support human life on as little as 1/10th to 1/3rd of an acre of land, while maintaining soil fertility. How are we able to do that? Because the figure for the amount of needed land includes the space necessary to also grow the green manures, mulches, and compost material to return to soil. Of that tenth to third of an acre, about 30% is used for growing food, the remaining 70% maintains the fertility. If we need 1/3 of an acre to feed someone, is there enough arable land in the world to do so? Here we are in luck because there is, according to statistics from the U.N Food and Agriculture Organization, a little over 1 acre of arable land for every person currently alive on the earth. And with permaculture techniques, have numerous ways to improve degraded land and increase the amount of land useful for growing food. So, on paper, it's possible to feed the current world population several times over. In practice there are numerous barriers to overcome, probably the greatest of which is the distribution of resources. Having plenty of arable land in the world to feed everyone is great, but that land is spread all over the world and our population, though on all 7 continents, are not living in the same proportions in the same areas of land. We can do it. Let's find some solutions. I'll end this with some questions for you: Other than resource distribution, what other problems do you see with feeding the world's population using permaculture? How would you go about making a difference?