• What happens if we can't find a low-carbon alternative to airplanes? Or big cargo ships that bring us goods from abroad?
  
• How would your town be different if there were no bridges? Or freeways?
• How would your town provide food, water, or power if it weren't connected to the nation's larger systems that deliver these goods?
• What would you do if you could have access to the Internet everywhere you went, anywhere in America?
• In Scenario #2, would you prefer to live in the country, or in the city? Why or why not? What would your daily life be like?

Transportation -- The first step was to rebuild the country's railroad network, replacing the old tracks with a new all-electric semi-high-speed rail network that can move people and goods across the entire country in under 36 hours. The network, which uses power from whatever local renewables are available in the area, now carries 90% of the country's freight, almost completely replacing long-haul trucks. (Losing the trucks also eliminated two-thirds of the wear and tear on the country's existing roads and bridges, so they don't need to be repaired or replaced nearly so often in the future. And it cut the country's carbon footprint by 15% in just a few years.) The train is also popular with passengers, most of whom prefer it to air travel for trips under 1000 miles -- a development which has eased the strain on the air traffic control system, and eliminated the need for airport expansions in many hub cities. The high carbon tax on air travel has also discouraged people from flying as much, though research into low-carbon jet engines has eased this somewhat, and will continue.

Cars of all sizes now run on electricity, too -- though people don't drive nearly as much as they used to. As cities rebuilt their aging water, power, and sewer systems, they took the opportunity to increase density and provide better urban transit options as well. Light rail and bicycle paths are now part of the urban fabric of most cities; and homes built close to them command a high market value. Lots and houses are a little smaller now; but the smaller homes are cheaper to heat, and the smaller yards use less water. As a result, most American families now only own one car, so more houses are being built with one-car garages.

Most American cities have followed the example of Europe's major cities, and closed off portions of the downtown core to vehicle traffic, leaving the area free for pedestrians and Segway riders. Homes and businesses in these areas are typically the most upscale and desirable in the region. But the quality of life is better on the other side of the tracks, too, because better transit and communications networks mean that poor and disabled people no longer have to afford a car to be able to work, shop, travel, and participate in the economy. One side effect of this is that people in cities are now healthier than those in the countryside, because they get more exercise through walking and biking.

Energy -- Wind farms have sprung up across the West in the railroad right-of-ways, supplying power for the trains. The power lines built into the tracks also bring the surplus energy into the cities and towns the railroad serves. Elsewhere, coal plants have been replaced by solar, wave-generation, geothermal, biomass, and other forms of electricity. Better battery technology has made these systems reliable and efficient, regardless of the weather or season. Both residential and commercial streets around the country have been lined with shade trees to provide natural cooling in the summer. A national effort to put inner-city kids to work putting reflective white paint on the roofs of over 250,000 commercial buildings and outfitting them with solar panels reduced those buildings' energy consumption by over half.

Overall, the average American uses only 40% as much energy and generates 90% less carbon than he or she did in 2000 -- and yet still lives a comparably comfortable lifestyle.

Water -- Water consumption is a less pressing issue now, due to the development of several effective large-scale seawater desalinization technologies discovered in the 2010s. Still, the earth's aquifers and ecosystems will need many generations to recover from decades of depletion; and global warming is still drying out many parts of America that were, until very recently, reliably green and wet. We're no longer outstripping our supplies; but even so, we must use water far more carefully than we once did.

Most of the major cities have completed the job of replacing their aging water lines with leak-free pipe, which should be good for another century or more. In a few cities, so much water was recovered from this that further water restrictions were unnecessary. At the same time, neighborhood greywater reclamation systems were installed in many local parks, often disguised as attractive water features. While not potable, this reclaimed water from sinks, bathtubs, and washing machines (but not toilets!) is piped to support park greenery and street trees, so even cities in the drier regions of the country have at least some green cover. Many parks have community gardens where residents grow their own food in season.

California and Texas have banned the growing of cotton, alfalfa, and rice -- three very water-intensive crops that absorbed much of the water output in those states. (Canada and the Pacific Northwest are now growing most of the country's supply of these three crops.) The cotton in American jeans and T-shirts has been largely replaced by industrial hemp, which will grow in far more places, and on far less water.

Communications -- Due to a national push in the 2010's to get broadband networks into most small towns, a large number of former city dwellers have made the exodus back to country living. Most of them work at home, running their own nationwide businesses, telecommuting to jobs in cities thousands of miles away, or taking online classes from the country's top universities. The cultural, economic, and intellectual infusion brought by renewable energy workers (who are dispersed everywhere) and these "broadband immigrants" has brought thousands of small towns back to life.

In the cities, universal free wireless has become just another city utility, as expected and normal as water or power. Voice-over-IP phones have largely replaced cell networks; and it's not uncommon to see people gathered with their laptops for business meetings in restaurants or downtown parks. In a new economy where information is money, every American has unlimited access to a communications infrastructure that puts markets, jobs, consumer goods, and information at their fingertips -- and thus empowers them to live where they want, doing what they want to do, working with the people they most enjoy.

The larger effect of all this infrastructure investment has been to make the country completely self-sufficient for its energy supplies, which in turn has created vast changes in its foreign policy. No longer dependent on foreign oil, the country has disentangled itself from the Middle East and other unstable regions -- which, in turn, has made the country much less interesting to terrorists and far more sturdy in the face of any kind of natural or human-made crisis. Many of the infrastructure improvements were financed by diverting money from the military budget, because leaders realized that strong infrastructure was an important key to the country's true long-term security. Because of these investments, America is truly ready for whatever comes.

Climate change happened -- faster than anybody expected. And, at the same time, we ran out of oil -- also faster than anybody expected, and before we could develop infrastructure that would enable us to use other resources. The astronomical price of energy quickly drove the industrialized world into a total economic collapse. The crisis created hordes of refugees and left governments at all levels broke. With no money to even operate the country's water, power, transportation, and communications networks -- let alone repair or upgrade anything -- life got nasty, brutish, and short in no time at all. Americans were on their own, left to survive on a frontier as inhospitable as any they faced in the 19th century.

For the rest of this story, read "Lord of the Flies." Or, alternatively, James Kunstler's "World Made By Hand."