Using all that CO2

You may try this in your own garden, but be careful if you make your own charcoal, the process can create carbon monoxide while it lasts. There is also the obvious fire hazards.

Yesterday I wrote at length about the futility of carbon taxes: Almost all the fossil fuel will be in the atmosphere within the lifetime of most of my readers anyway. Today I will tell you how we remove some of this carbon dioxide at a moderate cost, and in the process feed multitudes for thousands of years. It is really quite simple. Even if our high-tech civilization should fall apart, this particular thing is still easily within our reach. After all, I am talking about something that has been tried successfully before, ranging from about 450 BC to around 950 AD.

During this period, the Amazonian rain forest was populated by a native people which we suspect was the ancestors of some of the nomadic people living there after the European invasion. The soil in this rainy area is of poor quality, as the rain washes nutrients out of the ground and the rapidly growing plant life mops up what is left. Yet many patches deep in what is now forest have a strikingly fertile, deep black soil that is ideal for farming: The so-called Terra Preta, the black soil of Amazon forest.

When clearing forest, these people may have used smoldering instead of wildfires, covering burning trees and bushes to reduce them to charcoal. Charcoal can also be made to more exact qualities and quantities by recent but still fairly simple methods. The charcoal was mixed with manure, compost and  the occasional pottery shard and buried in the resource-poor soil, creating a new type of dark soil with amazing properties. It yields triple the harvest without any extra fertilizer, binds nitrogen and even regenerates itself for more than 2000 years – presumably until it is removed by force.

The charcoal, of course, consists largely of carbon, which is not released to the atmosphere as it would have been through burning. Once out of the air, it stays in the ground for the aforementioned thousands of years. This has historically not been a great idea, as the climate has become slowly colder for about 10 000 years, until quite recently. Today we have a new chance: There hasn’t been this much carbon in the air since the age of dinosaurs. If there ever was a time to mass produce terra preta, now would be that time.

In addition to the old-fashioned kilns for making charcoal, modern technology opens for a process of pyrolysis, where leftover biomass (like straw from corn etc) in addition to wood can be broken down to “biochar”, releasing flammable gases in the process that can not only supply continuing energy to the process but also produce energy. This may still be out of reach for parts of the third world, but while you were not looking, most of the tropical nations stopped hunting with spears and started getting mobile phones. Whether this in reality turns out to be part of the solution or part of the problem, I cannot say for sure.


 OK, we have a way of extracting carbon permanently (or very nearly so) from the atmosphere, in the process greatly increasing crop yields without artificial fertilizer. It is possible even with simple technology, and can use either wood or worthless byproducts from agriculture. The new fertile soil regenerates itself beyond the foreseeable future. Should our civilization one day collapse, having transformed the soil of the tropics this way would vastly improve the chance of any survivors to bounce back quickly.

Why aren’t we already doing this? What could possibly stop us from cheaply, harmlessly providing food for our descendants for thousands and tens of thousands of years into the future?

Well, there is the small detail that you can get more crops THIS year with less work and less expense, by using artificial fertilizer.  Since the overwhelming majority of people are like your neighbors, not like you, this is reason enough. The second reason is of course that they have never heard about it. Now you have. For more information, just search the Internet for “terra preta” and “biochar”, while we still have an Internet.


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