Talk TED Talks: Our Line in the Sand

Hurricanes, earthquakes, floods, droughts. These are but a fraction of natural phenomena that wreak havoc on the land we live on, bringing more death and suffering than a band of Dark Jedi. However, there is another addition to this list, far less known but just as environmentally disastrous: desertification. For those of you who are unaware, desertification is the process of Earth’s arable land being slowly transformed in desert, caused primarily by erosion and human activity.

Sadly, the most accurate explanation of what Earth is turning into is Tatooine from Star Wars, a veritable uninhabitable infinite desert. In northern Nigeria, the southern border of the Sahara desert migrates approximately 600 metres every year, making the dunes consume more than a metre of cultivable land every day. To put that in perspective, a Nigerian farmer could simply look out into the desert, and count (not calculate, count) the number of days that he has left before the desert consumes his home and he is forced to move his family elsewhere. It is predicted that by the end of the 21^st century, one third of the entire Earth’s arable land will have been encroached on and consumed by deserts. But now to the good news!

At a TED conference in July of 2009, architecture student Magnus Larsson presented his radical solution to prevent the desert encroaching villages in northern Africa. His solution is a heavily modified version of the “Green Wall”, a plan by 23 African countries to plant a line of trees across the southern border of the Sahara desert. Instead of building a wall of trees (which were cut down by poor farmers who needed firewood), Larsson’s plan involves constructing a barricade, but one that is built out of the sand itself. Larsson’s proposal involves using a common, wetland bacteria, Bacillus pasteurii, to modify the sand into a sturdy construction material. This process occurs when chemical reactions within the bacteria produce calcite, which fill in the gaps in the sand, creating what is, for all intents and purposes, sand concrete. Experiments in petri dishes have shown that pasteurii can solidify sand in less than one day. Obviously, this duration would increase given that more sand will be need to be hardened, but a couple of years is more than reasonable for a Great Wall of Africa, especially considering how short term solutions have yielded no significant results.

The process for producing a sand barrier is reasonably straightforward. One would fill a balloon-like structure sand and the bacteria, and allow the sand dunes to pass over them. Once the sand has consumed the balloon, the balloon structure is simply “popped,” disseminating the bacteria within the sand. The sand around the edges of the balloon structure would be solidified, and the sand in the centre of the balloon would remain as grains, which could be excavated by hand, or eroded away by wind. Given the considerable amount of sand, one could return after a few years and begin to grow trees in that region of the desert, alternative, bacteria could be directly injected beneath the surface of the sand, allowing the sand concrete to take virtually any shape desired. The massive network that would be formed could be used to provide structural support to another tree wall, but also provide shelter for countless people, providing protection from the elements, shade, as well as the ability to harvest condensation for water (or “moisture farming” if you’re loving the Star Wars references as much as I am).

Humans as a species have wrought destruction and mayhem virtually every aspect of nature by playing god with the environment. Luckily, our blind ambition and our unquenchable desire for meddling have actually resulted in an idea that will protect both human society and the natural world. Desertification is a catastrophic phenomenon, so it is with Larsson’s proposal that we must draw our line in the sand.