Re-Ruralization

Although the worldwide trend for many generations has been for people to move from rural to urban areas, that may have to change in the near future. Even mid-sized cities, let alone the "megacities" (such as Tokyo, New York, Delhi, Mexico City, Buenos Aires, and others) may not be sustainable in a world which has effectively run out of fossil fuels and the amazing levels of energy they contain.

In the 21st century, re-ruralization may have to be the trend for many people. Small and efficient multi-level "forest gardens" may be necessary to grow food without fossil fuels, combining cutting-edge techniques like permaculture design with others that have been around for millenia.

Also, it will probably become common for each house to collect its own water (in the form of rain hitting the roof), generate its own electricity (via solar panels, and perhaps wind turbines of some sort) and utilize virtually all of its "waste" in productive ways.

Buckminster Fuller proposed this decades ago. And now, with the ubiquity of the Internet, and the ability for more and more people to work and communicate from wherever they are, many people may find that they prefer living in more rural areas, while still having access to much of what they formerly had in the city.

Personal preferences aside, a failure of the "green revolution" (which has provided cheap, plentiful food for the First World through the massive agricultural use of fossil fuels) could easily cause a planetary "population adjustment" to more sustainable levels.

If that does happen, we'll have to come up with a new way of feeding ourselves, and re-ruralization may be our best option.