Infrastructure Megaprojects: Arable Land

So now we have energy and fresh water. The next obvious human need is food. Food production comes down to three things: water, land, and fertilizer. We have a solution to get arbitrary amounts of fresh water, and we can develop fertilizer from the leftover potassium from the desalination plants. That leaves land.

Large sections of the United States are desert, and much of the rest is trending that way. Deserts may not all be dead and barren, but they're not particularly useful by human standards. The growth of deserts is a huge problem.

So let's fix them. It's possible to reverse desertification by planting trees. It's counter-intuitive, but think about it this way: plants don't just absorb water, they also release it through their leaves. That means that whatever rain that's fallen, the trees hold it temporarily, then release it back to the environment to rain out again. That means that whatever rain falls in the area stays in the area longer, cycling through the local ecosystem, rather than just evaporating and leaving.

There are about a quarter million square miles of desert in the continental US, and about as much semi-arid land. Figure fifty trees per acre, and that's sixteen billion trees. Sixteen billion trees to increase our useful arable land area by 20% sounds like a pretty good deal!

If you think that number sounds totally unreasonable, think again. During the great depression we planted three billion trees. More recently, seven billion trees have been planted in less than a decade. Moreover, this requires almost totally unskilled labor, so it's a great jobs project.

Of course, once the forests are established, we wouldn't just leave them untouched. Forests are great, and they have all sorts of positive effects on air quality, improving the health of those nearby. But forests aren't the only end goal. Over time we'd need to make some reclaimed areas into farms, taking advantage of the rebuilt soil. But we'd do that in a planned and controlled fashion. We need to make sure that we don't reclaim the deserts, only to recreate them later.