The Dirt that Solves Global Warming


By the end of the century, 182 million sub-Saharan Africans could die of disease directly attributable to climate change.  By 2030, more than 60 million more Africans will be exposed to malaria if temperatures rise by 2 degrees Celsius.  One-sixth of the world’s population will face water shortages because of the retreating glaciers [1]. Because political and social steps have not been taken earlier, the deprecating effects of carbon emissions have taken their toll.  Terra preta, a carbon-sequestering soil, offers the urgently-needed solution.

As of 2008, the United States consumed 20.4 million barrels of oil per day [2].  Because US households exceed the carbon dioxide levels of the rest of the world by six times, a solution for greenhouse gases is more imperative than ever in the States.

Because the issue of carbon emissions is now time-sensitive, carbon sequestration has attained considerable importance.  For both higher productivity and emission reduction, terra preta has dominated the scientific backdrop of global warming.

Current Approaches

The current approach to global warming is two-pronged: political and scientific.  With the world leaders taking steps by setting goals of lower global emissions such as the European Union mandate for limiting temperature rise to 2 degrees, politics has found a heavy weight in environmental preservation.  Because political movements to address global warming remain stagnant, scientific solutions will clarify our treatment of the environment and offset committed harm.  Up to this point, what’s been emphasized today has had a less effective peanut butter spread effect.  After concentrating funds and manpower on different areas of invention with little to no success, terra preta provides the opportunity to remain environmentally-cautious and to attain power efficiency.  Perhaps the cleanest alternative source is wind power – the greatest setback being that the cost financially and spatially is too great compared to a lower cost to higher output of fossil fuel.  Furthermore, 20 mph winds are required for cost-effective operation, and winds are locally intermittent.  Alternative fuels like corn ethanol aggravate global poverty as food prices are driven up while agricultural farm land is used for energy cultivation.  Another public favorite, nuclear power, has several negative impacts.  Not only is the nuclear waste projected to be the size of Yucca Mountain with deadly radioactive consequences, but also the high terrorist potential posed by countries with nuclear capability causes international conflict.  Financially, uranium has become forty dollars more expensive in five years.  Lastly, “the Oxford Research Group concludes that the nuclear fuel cycle is responsible for emitting 84 to 122 grams of carbon dioxide per every kWh, mostly from mining, plant construction, and plant decommissioning” [3]. All in all, the current methods of reshaping our energy economies have rendered little to no success.


Terra preta do indio, also known as agrichar/biochar, is the most plausible answer.  In short, agrichar is the antithesis of how many climate change scientists approach the global warming problem.  Rather than finding a way to reform our energy economies, which is a long process the Earth cannot afford, agrichar mitigates and offsets current CO2 levels.  Through a process called carbon sequestration, agrichar creates permanent repositories for holding carbon dioxide.  Geologic formations and terrestrial ecosystems are the two ways to accomplish this goal.

The pores in various geologic formations have formed an impermeable membrane with overlaying layers to prevent material from leaking out. To this day, they hold large amounts of oil and gas, accumulated over centuries.  By taking out the natural gas and oil in the rock repository at this time, carbon dioxide can be permanently injected in its place.  In particular, saline formations have high retention of materials, depending on size, permeability, and heterogeneity of the formation in question.  Not only will we be able to store away tons of emissions, but also will we take advantage of a reservoir of natural resources.  At this point however, permeability is still in question: the existence of carbon retention is true enough, but the retentive quantity is still under research.

One of the most successful approaches to this method of carbon sequestration in the world today was discovered mistakenly in the Amazonian rainforests.  Though similar in nearly every aspect to the yellow oxisol that surrounds these patches of dark soil, terra preta hides a truly precious ability.  Unlike most soils and fertilizers used in today’s gardens, terra preta do indio has a property of which when burned, it does release some carbon dioxide but retains more than 80% – an astonishing discovery that has dubbed it a carbon negative fuel.  According to Jeremy Faludi, a professor of green design at Stanford University, “[With] twenty times the carbon of normal soils, terra preta is the legacy of ancient Amazonians who predate Western civilization” [4]. Amazonian Dark Earths have high carbon contents of up to 150 g C/kg soil in comparison to surrounding soils with 20-30 g C/kg soil.  The potential for carbon lock-in for this particular soil type could offset the emissions that increase daily around the world.


Comprised of pottery shards, fine charcoal bits, and waste, agrichar itself may not seem very impressive.  However, the effort and energy required to take normal, infertile soil in the backyard and create agrichar isn’t much in comparison to other forms of energy.  The pyrolyzation of farm waste at low temperatures and simple grinding of charcoal bits can recreate what the ancient peoples of Amazon had done for their very own land.  Pyrolyzation is the process of low temperature burning of biomass such as leaves, branches, or soil without oxygen [5]. Because it prevents the release of carbon dioxide, “[pyrolyzation] makes bioenergy carbon-negative and improves soil health.”

Scientists have found that the most fertile soils contained 40 to 90 percent charcoal [5]. Though this finding was counterintuitive for most soil scientists because charcoal is an inert material whose effect on the soil’s productivity was assumed to be little to none, they found that charcoal in fact made the soil far more fertile due to its partnering community of bacteria.  Within the charcoal itself, there are resins that contain nutrients released by the bacteria’s enzymes that nourish the plant [6]. These resins are nourishing because they absorb minerals from rainwater and the environment.  Once a corresponding soil bacterium enters this particular environment, nutrients are then released into the plant.  In addition, plants are able to respire more efficiently.  The process of biosequestration modifies the key photosynthetic molecule, RuBP, allowing for higher retention of carbon dioxide.  No longer does the soil need to sit fallow, but also, the plant yield is much higher even without the use of fertilizers.


Terra preta offers various financial, social, economic, and environmental benefits in comparison to current solutions [7]. Expansion of terra preta technology is simply word-of-mouth, which reduces the huge drain on financial expenses for capitalist infrastructure expansion.  The next step has already been taken in Canada and Australia in conventions with the United States’ most qualified bio-geochemists and Australian biofuel engineers.  Lehman of Cornell University is also conducting research and studies to maximize productivity of the dark soils and increase the possibility of mass production.  Although “the techniques of the Amazonians remain an enigma, their system of slash-and-smolder locked half of the carbon of burnt vegetation in a stable form like terra preta instead of the carbon emitting process of slash-and-burn” [8, 9]. Rather than take up several initiatives with little chance of success, production and distribution of terra preta will provide nations a more solid response to our dying environment.



  1. Rosen, Yereth. “Carbon emissions increasing acidity in Alaskan seas.” The Christian Science Monitor. N.p., n.d. Web. 13 Jan. 2011.
  2. Hinkle Charitable Foundation. <>.  October 20, 2010.
  3. “What is Carbon Sequestration?” NETL: the Energy Lab. Department of Energy, n.d. Web. 30 Nov. 2009. <>.
  4. (Lehmann et al. 2002, Sombroek, 1966; Smith, 1980; Kern and Kämpf, 1989; Sombroek et al., 1993; Woods and McCann, 1999; Glaser et al., 2000).
  5. Moore, Frances C. “Carbon Emissions.” Eco-Economy Indicators. Earth Policy Institute, 9 Apr. 2008. Web. 30 Nov. 2009. <>.
  6. Bidstrup, Scott. “Saving The Planet While Saving The Farm.” Veritas Et Ratio. Scott Bidstrup, 20 Aug. 2007. Web. 30 Nov. 2009. <>.
  7. Harvey, Fiona. “Black is the New Green.” Financial Times. N.p., 3 Mar. 2009. Web. 30 Nov. 2009. <‌/‌ec0-020b-11de-8199-000077b07658.html>.
  8. Zaks, David, and Chad MonFreda. “Terra Preta: Black is the New Green.” World Changing. N.p., 14 Aug. 2006. Web. 30 Nov. 2009. <>.
  9. Casselman, Anne. “Special Report: Inspired by Ancient Amazonians, a Plan to Convert Trash into Environmental Treasure.” Scientific American. N.p., 15 May 2007. Web. 30 Nov. 2009. <>.

Kristi Lui is a senior at the Harker School in California.