Feeding & fueling the 9 billion-sustainably
Sustainably nourishing and fueling the nine billion people assumed to be living on Earth in 2050 is one of humanity’s grand challenges. Today, about one billion people are malnourished globally—and around one billion, mainly in the industrial world, are obese.
According to estimates from the Food and Agriculture Organization of the United Nations, global food production will rise by 70% or more until 2050, mainly from increases in yields. Cropland expansion for food production is generally assumed to be modest, perhaps below 10% until 2050.
At the same time, there is the hope that bioenergy could provide huge amounts of clean, renewable energy, helping curb greenhouse gas (GHG) emissions from fossil fuel combustion. But, can we expect a strong growth in bioenergy production over current levels of ?50 EJ per year, given the need to counteract further biodiversity loss and given, too, that food and bioenergy require the same limited resources, namely, fertile land and freshwater, and that even relatively small biofuel programs have recently contributed to food price surges?
The answer is: yes, to a certain extent—if we do it right, which means abandoning the delusion of “silver bullets” and instead trying to better understand the dynamically interwoven social, economic, and ecological factors shaping the future global land system.
First, we need to acknowledge the enormous importance of future diets. To date, income growth has involved a transition from “poor” diets in which staple crops such as cereals or potatoes deliver most of the calories, to “rich” diets with an ample supply of animal-derived protein.
While our priority is reduced hunger and malnutrition, there are many dietary options. All diets depicted in the graph—from frugal to rich—supply sufficient calories and protein for a world population of nine billion in 2050. The “frugal diet” would require globally equal distribution of food containing a low level of animal products to abolish hunger. The “rich diet” would come closer to making the food supply levels currently enjoyed in the USA and Europe available worldwide. Hunger might still persist, even at that level of supply, however, if large inequalities in food distribution remain.
The global energy crop potential in 2050 depends on future diets (left) and yields of food crops (right). Moving toward a more modest diet always results in higher bioenergy potentials, while stronger agricultural intensification increases the energy crop potential only if we abstain from eating more animal products
As the graph shows, the bioenergy potential in 2050 strongly depends on future diets: rich diets which need more cropland and rough grazing land for cattle leave little land for bioenergy crops. While people are unlikely to choose bioenergy over food, recognition of the adverse health effects of overconsumption, as well as promotion of vegetarian foods could persuade people to adopt environmentally less demanding diets, even in wealthy countries.
According to environmentalists, more widespread adoption of organic agriculture could reduce the adverse environmental effects associated with intensive agriculture. As organic yields are currently substantially lower than those of the most intensive conventional production methods, natural ecosystems, including forests, would have to be converted to crop and forage land if the aim should be to generate rich diets with organic agriculture. Thus, while agricultural intensification may increase some environmental pressures, it also helps to alleviate others such as deforestation. Foregoing yield gains from intensification therefore also has ecological costs, provided it does not go hand in hand with changes in consumption. These trade-offs need to be better understood.
Growth in yields need to be reconciled with a reduction in the adverse effects of agriculture— a strategy called “sustainable intensification.” While formulating this goal is a useful first step, solutions are a long way off. Moreover, proper implementation of related technologies needs to be based on context-sensitive approaches that carefully consider local socio-cultural, economic, and ecological conditions. People living off subsistence agriculture must not be forced to accept development schemes imposed by others.
Addressing the food versus fuel dilemma goes beyond diets and agricultural technology. One strategy is the “cascade utilization” of biomass—reuse and recycling of biogenic wastes, by-flows, and residues. Recent studies suggest that the energy potential of agricultural residues, municipal solid wastes, and animal manure in the year 2050 may be approximately 100 EJ per year, about as much as the potential for dedicated energy crops. Many of these resources are sustainable and use synergies between food and fuel production, but some require careful scrutiny. For example, withdrawing organic matter such as straw from cropland may result in soil degradation and loss of soil organic carbon. This would jeopardize long-term sustainability of agriculture and result in higher agricultural GHG emissions. More evidence is needed to determine safe levels of use.
We also need to consider different land qualities. Approaches such as “environmental zoning” can usefully mitigate adverse effects and optimize outcomes by allocating to each region the most appropriate uses of the land. Of course, the need to reduce pressures on ecosystems and to reduce the rate of biodiversity loss must be integral to this approach.
Last but not least, we need an integrated approach to better understand the GHG emissions related to changes in land use. Currently there is a heated debate on the emissions of bioenergy related to “indirect land-use change” or iLUC. For example, if bioenergy is produced on land currently used for food crops, the production of food will move elsewhere. If it results in replacement of carbon-rich vegetation such as forests by cropland, iLUC implies a large “carbon debt,” and bioenergy may even cause more GHG emissions than the fossil energy it replaces.
This problem can be avoided by taking an integrated view of the land, where all changes are taken into account and there are no “indirect effects.” The goal must therefore be to manage the global land system in an integrated manner—to optimize outcomes in terms of food, feed, fiber, and energy supply and to maintain healthy, diverse ecosystems capable of supplying a large range of ecosystem services, including carbon storage.
The Global Energy Assessment