“20 points of broad scientific consensus on GE crops”

The title of this short post–20 points of broad scientific consensus on GE crops–seems rather accurate, based on my own extensive knowledge in this subject. The piece cites peer-reviewed studies or position papers from scientific societies. In fact, they list only a few of the position statements from scientific societies on the safety of consuming present-day GE crops. Others exist, including those from major European scientific societies.

The lead author, Pamela Ronald, is a highly respected molecular geneticist and her husband is an organic farmer.  Thus, as a pair, they bring a somewhat unique perspective to the topic of genetic engineering. (Just for clarity, Dr. Ronald’s husband is not a coauthor on this particular piece, but they do publish jointly.)

(Nearly) Sustainable Food Systems, Part II

While leading students on a University of Kentucky Education Abroad trip to Nicaragua last year, we had an enriching visit with Rama Indians near Bluefields. Meeting our Rama hosts—who live very simply and with appreciation for their forest—was indescribably special. For all of us, it was the most memorable part of the study tour, made especially so because we personally witnessed the suffering of the Rama at the hands of illegal deforestation.

The Rama taught us about their traditional, forest-based food system. They rely in significant measure on the forest for edible plants, medicinal plants, and wildlife (Figure 1). They also cultivate various well-recognized crops, including cassava, plantain, and beans (Figure 2).

Figure 1: Our Rama host explains the alimentary and cultural value of the ebu fruit, the trunk of which is in the background.
Figure 1: Our Rama host explains the alimentary and cultural value of the ebu fruit, the trunk of which is in the background.

One of the most common traditional farming systems in regions of tropical forest (and sometimes temperate forest) is called slash-and-burn. In slash-and burn-farming, plots of forest are cut, but most of the forest is left intact. The fallen vegetation is allowed to dry, then it is burned, thereby releasing nutrients for crop uptake. The people then grow crops for two to six years, eventually allowing the plot to revert to forest.

The Rama Indians we visited did not practice slash-and-burn, but rather, slash-mulch (Figure 3) (Thurston, 1992). In such a system, a parcel of forest is cut but not burned. Nutrients are released at a slower pace through natural decomposition of the fallen vegetation. Thus, nutrients would be less subject to runoff into waterways than in a slash-and-burn system.

Every time I ponder it, I reach the conclusion that this is the most sustainable farming system I have ever witnessed or studied. In a slash-mulch system, diverse forest covers most of the land at all times. Plots for crops are limited in size, temporary, and surrounded by forest, so there is an abundance of habitat for native wildlife, vegetation, and other biota. Furthermore, the soil surface in the plots is never completely bare, which would expose it to erosion. It is low-yield agriculture. They grow crops without external inputs, mechanization, and or irrigation. However, it serves the needs of the Rama Indians, with apparently quite modest environmental impact compared to the large-scale, highly productive farming systems that emerged in the 20th century.

We saw in Part I of this two-part series that the hunter-gatherer existence—sustainable though it is—would be woefully inadequate to feed our present population. But in contrast to a hunter-gather existence, a slash-mulch system incorporates crop production, and it does so in a way that seems environmentally sustainable. So how would that system perform as a food system for our present population of 7.3 billion people?

Thurston (1992) indicates that a slash and burn system requires 15-30 hectares per person. I’ll assume that a similar range applies to a slash-mulch system. The UN Food and Agriculture Organization reports that Earth has approximately 2.9 billion hectares of land suitable or very suitable for rain-fed crop production (UN-FAO. 2009). Dividing 2.9 billion hectares by the conservative figure of 15 hectares per person gives us about 193 million. One-hundred ninety three million people represents only 2.6% of our present population—nowhere near

Figure 2. Plot of cleared forest used for cultivation of bean, plantain, and other crops.
Figure 2. Plot of cleared forest used for cultivation of bean, plantain, and other crops.

all the humans presently living on our planet. If it turns out we need 30 hectares per person, instead of 15 hectares, we can feed a just a little over one percent of our present population.

The UN-FAO (2009) estimate indicates that a total of 4.2 billion hectares of Earth’s surface is suitable in some way for rain-fed agriculture, even if marginally so. Let’s be as optimistic as possible and assume that all of that land is available for a slash-mulch food system (leaving none for urban areas, forests, wetlands, and biofuels). Let’s also assume that we only need 15 hectares per person. Dividing 4.2 billion by 15 hectares per person gives us 280 million people that Earth can support. That’s less than four percent of our present population of 7.3 billion. In this food system, over 96% would have to starve ourselves out of existence.

And what about the ones yet to be born, as our global population continues to grow?

All of this is made even more challenging by climate change. Given the reality of a rapidly changing global climate (National Academies Press, 2014), making sure everyone has the food security and food sovereignty they deserve is a moving target.

The two food systems featured in this two-part series may provide for a noble life, possibly one of great freedom. But they are lives of great material simplicity, and in all my professional travel in four continents, I’ve never gotten the sense that the average citizen in countries with developed economies cares to forego the material lives some of us enjoy. In that sense, maybe the food systems described in this series are not actually sustainable after all, in that they are not socially acceptable—a fundamental pillar of agricultural sustainability.

One can fairly argue that neither of these traditional food systems represents modern farms with a sustainability focus, and that is a valid point. However, these food

Figure 3: Soil cover from residue of forest and of wild vegetation. This is conceptually very reminiscent of our no-till cropping systems.
Figure 3: Soil cover from residue of forest and of wild vegetation. This is conceptually very reminiscent of our no-till cropping systems.

systems remind me of how far we have come with agriculture, as well as how far we still need to go, when we consider both food security and sustainability. I often wonder how we will meet the challenges of:

  • Food security for over seven billion people today; and,
  • Food security for well over nine billion in a mere 35 years (Gerland et al, 2014); and,
  • The subsistence life experienced by many millions of farm families throughout the world; and,
  • The likely dietary choices of a global middle class that will more than double in two decades (MacLennan, 2015); and,
  • Sustainability, in the sense that our farms will be capable of feeding humans for many centuries with minimal negative impact on the Earth and on the social fabric of human societies.

Are there farming systems that can adequately address all these challenges? And if so, what are the costs and the unanticipated consequences of such a system? A thoughtful and balanced approach to such questions is critical because my work on four continents suggests to me that all farming approaches have good ideas, all have limitations, and all have costs and unanticipated consequences.

If you are reading this post, you and I undoubtedly agree that we need to improve the sustainability of our present food system. But a bigger question is not, “Whether,” but “How? “ How do we measure “sustainability”? More importantly, which costs are we personally willing to pay? And who decides which costs are imposed on the general public at large?

These calculations emphasize to me the depth of the challenges facing our children and grandchildren. One of the concepts I find useful is called sustainable intensification (FAO-UN, 2011; Godfray and Garnett, 2014; Pretty, 1997). Unfortunately, this phrase is used to defend whatever practice or technology one favors for producing food in the future. I think that is misguided. Basically, the simplest understanding of this phrase is that it is beneficial to humans and the environment to produce more crops per unit of land (=intensification) in sustainable ways. (And I am referring to sustainability in a broad sense.) I don’t see a flaw in this concept.

But even the concept of sustainable intensification is not a protocol, or even a road map—it is merely a useful way to think about ways to address some of our food-system challenges. I simply do not see easy answers. I see only tradeoffs. Global food system sustainability is like global energy sustainability: no one has found a “magic bullet,” because there is none.


  1. Diamond, J. 1997. Guns, Germs and Steel: The Fate of Human Societies. Norton and Company
  2. FAO-UN. 2011. Save and Grow: A Policymaker’s Guide to the Sustainable Intensification of Smallholder Crop Production.
  3. Gerland et al, 2014. World population stabilization unlikely this century. Science Express1126/science.1257469
  4. Godfray and Garnett. 2014. Food security and sustainable intensification. Phil. Trans. R. Soc. B 2014 369, 20120273.
  5. MacLennan, D. 2015. In 4 Charts: The Past, Present, and Future of Food Security. The Plate: National Geographic Daily Discussions on Food.
  6. National Academies Press. 2014. Climate Change: Evidence and Cause, An overview from the Royal Society and the US National Academy of Sciences
  7. Pretty, J. N. 1997. The sustainable intensification of agriculture. Natural Resources Forum 21(4):247-256.
  8. Thurston, D. 1992. Sustainable Practices for Plant Disease Management in Traditional Farming Systems. Oxford and IBH Publishing Co. 279 pp.
  9. UN-FAO. 2009. The Resource Outlook to 2050.