I am aware of the possibility that we are or will be in overshoot. However, I am committed to doing what I can to prevent a catastrophic die-off, if it can be prevented. I am committed to going down, if I must go down, fighting what I think is still probably an unnecessary die-off. I want to do whatever I can to keep alive a possibility of a humane solution. I agree with everyone that that humane solution has to include radical population control, but for it to be humane, it needs to be consensual and a cultural norm, somewhat as aversion to tobacco has become a cultural norm in many parts of the United States.
The situation varies a lot from region to region, country to country, and continent to continent. As Benbrangwyn says, people are doing hardheaded scientific research and are coming to the conclusion that Great Britain can probably just achieve food self sufficiency with a concerted effort. You have suggested that it is suspicious that people are claiming that we can *just* get by, but I have only heard that claim made for Great Britain (or sometimes England, which Benbrangwyn suggests may not be the case), and I suspect, from my own geographic background, that it is probably true that England or Great Britain could just get by.
Ireland, by contrast, will have it easy. On the other hand, a country like the Netherlands has really no hope of complete food self-sufficiency. The Dutch, who will also face a scary time with rising sea levels, are going to have to hope that their neighbors will have compassion.
China and India are probably in serious trouble, for somewhat different reasons. Both are near self-sufficient now, but only thanks to chemical fertilizers. I think that we can probably compensate for a loss of chemical fertilizers with green manures and thorough recycling of human (and animal) wastes, properly composted, back into the soil. In China, however, they have seriously depleted and seriously polluted their water supply to the point that they depend on fossil-fuel-powered pumps for a dwindling supply. They are now also in the process of depleting needed agricultural land through urban and industrial development and contamination. As for India, the problem there is runaway population growth, which will very soon result in a population above any conceivable carrying capacity. (Likewise Bangladesh, which also faces the same problem of land loss to rising sea levels as the Netherlands.) Egypt is another country in serious trouble due to a high population relative to arable land and the Nile Delta's vulnerability to rising sea levels. There are other pockets of trouble scattered around the world, such as Rwanda and Burundi, Java, and so on.
Still, I think on a global basis, we are probably still within our carrying capacity, but only with a concerted effort and a coordinated network of plans.
As for the United States, where you and I apparently both live, mos6507, I really think that there is little question that we can be self-sufficient in food. Apart from unnecessary imports such as organic kiwis flown in from New Zealand or Chile or beef frozen and shipped from Honduras, I think that we still are self-sufficient in food. If we converted our massive soybean and corn fields from production for massive factory meat farms to smallholdings intensively cultivated for human consumption, I think that there is no question that the United States would have an abundance of food, with a surplus to share.
Apart from the question of compassion, I do not think that it is remotely realistic that any but maybe the most isolated town (maybe a town in the Faroe or Aleutian Islands) can have any hope of safe self-sufficiency. As a geographer, I like to look at maps, so I know that Totnes is just 6 miles (a two-hour walk) up the road from Torbay, an urban area with 134,000 people. Do you really think that those 134,000 people are going to calmly face starvation while their neighbors up the road are living well?
Just as it is inevitable that we are going to have to live with less energy, it is inevitable that those with land and food are going to face masses of very motivated people without enough land or food. Just as we face a choice between planning for a future with less energy or facing chaos when it hits, we also face a choice between involving our neighbors and taking their needs into account in our planning or facing desperation and violence from those neighbors when crunch time comes.
You mention Great Barrington. I don't know if you live there. Great Barrington is a relatively isolated (and affluent) small town in western Massachusetts, for those of you who don't know it. However, the denser and poorer city of Pittsfield is just 20 miles away. That's a day's walk for a fit person, and even if a less-than-fit and hungry family had to sleep in the fields along the way (after plundering them for an evening meal), they could get to Great Barrington in two days or so. The cities of Springfield, Chicopee, and Holyoke, with their hundreds of thousands, are only about 40 miles away. If word traveled that food was to be had in Great Barrington, and/or in towns along the way (and word would travel), you can believe that those people would make the trek.
What good will transition planning for Great Barrington or Totnes be if it does not take this reality into account? And I would argue strongly that a town defense force would be an ineffective response. Not only would it take large amounts of needed labor away from efforts to meet basic needs, it would also probably be ineffective considering how outnumbered the townspeople would be and the easy access to firearms in inner cities, in the United States at least.
On a global level, this may be an issue as well. One option might be for the United States (or the United Kingdom) to make itself a fortress and fend off demands or attacks from Asia or other crowded places. But in an age of intercontinental nuclear missiles, this could be a gruesome option. Far better in my view, would be to help create a global movement to address our difficult reality head on and offer international cooperation and even food aid, where possible, to nations that implement effective programs to bring about rapid negative population growth by largely forgoing reproduction.