Traditional agriculture has dramatically altered much of the natural landscape (mostly hardwood forest, both in temperate zones and in tropical rainforests), replacing it with verdant fields of corn, wheat, and all the other food crops that the world has come to expect on demand. It is estimated that as of 2008, the total land mass now under some form of organized farming (including grazing lands) is equivalent to the entire continent of South America. While the obvious benefits of farming cannot be denied, rearranging the landscape in favour of crop production has regrettably resulted in unintended adverse consequences, ushering in an era of greatly diminished ecosystem services and functions, and contributing in a major way to an acceleration of the rate of climate change.
Illustration: Jayachandran / Mint.
The earth is currently in a warm period, and because of the heavy dependence of agriculture on the use of fossil fuels in most developed countries (in the US, one-fifth of fossil fuel use is for crop production), climate change has been accelerating at an ever increasing rate over the last 20 years, largely due to greenhouse gas released into the atmosphere (mostly CO2). Deforestation of the world’s tropical rainforests has become common practice in order to make room for new farmland as populations continue to increase. Since there are fewer trees to sequester the extra burden of CO2, it remains in the atmosphere and traps heat from the sun.
Climate change is the direct consequence of our quest for achieving a reliable, sustainable food supply. Ironically, this single imperative is degrading both the agricultural and natural landscape to the point of placing our long-term survival as a species at high risk. Can anything be done to slow or reverse this process?
If the forests that once existed could somehow be allowed to flourish again, then there could be a significant turnaround in the current trend. The Food and Agriculture Organization (FAO) states this in real terms of just how much carbon forests are capable of including into their trunks, roots and limbs. It also laments that farmland is the main reason we cannot implement such a simple, yet effective, programme of climate modulation. Other experts agree with FAO, including visionaries such as Al Gore and Wangari Matthai (both Nobel laureates). Vertical farming within the built environment and applied on a global scale would allow for the return of vast tracts of altered landscape back to its original state: namely, mixed hardwood forests. This, in turn, would provide a natural mechanism for removal of excess atmospheric CO2 and put the brakes on our runaway climate so that we may have a reasonable chance of adjusting to slower climate change regimes.
Critics of this scheme are quick to point out that planting and growing trees is a slow process (20 years from seed to mature tree) and would require unprecedented cooperation among all nations experiencing severe deforestation to be truly effective. If they are correct, then they also have to deal with the fact that doing nothing is tantamount to giving up. This is unacceptable behaviour. Nonetheless, assume for the moment that the “naysayers” have their way and nothing interventional happens to reverse the current trend in climate shift over the next 50 years. Then we would be forced to invent another way to produce food, or the human species would soon join the ranks of all the other extinct mammals that preceded us on this evolutionary journey.
In this doomsday scenario, vertical farming becomes the only viable strategy for feeding all of us, in a world in which the majority of farmland fails, as catastrophic environmental changes make it impossible to raise significant yields of any crop anywhere on the planet. Growing food in tall buildings within the built environment is not only possible given the clever application of current state-of-the-art technologies, but offers numerous advantages over the present situation. It would allow for continuous crop production. Since multiple layers of a crop on each floor would be the norm, a significant amount of farmland could be reclaimed. As an example, a single acre of strawberries grown indoors is equivalent to at least 30 acres of strawberries grown outside. Additional advantages include no crop failures due to adverse weather events, and a dramatic reduction in the use of fossil fuels. There would be no agriculture runoff, as all water would be recycled, and ecosystems damaged by conversion to farmland could be left alone to repair themselves (see the demilitarized zone between North and South Korea for proof of concept).
A wide variety of controlled-environment growing technologies exist (hydroponics, areoponics, drip irrigation, to name a few of the more popular ones) and could easily be adapted to mass production strategies. All crops would be grown under strict organic conditions using chemically defined nutrient solutions tailored to each species of plant.
One useful by-product of indoor farming is the production of pure drinking water, collected by dehumidification. Another is energy realized from the recycling of inedible portions of harvested crops into waste to energy strategies. In the end, those urban centres employing vertical farms to obtain most of their daily nutrition would be able to sustain such efforts indefinitely, thus becoming truly self-sufficient. It is expected that there will be enormous economic advantages for cities that follow this path to food sovereignty.
Dickson Despommier teaches at Columbia University. Comment at email@example.com