The world is increasingly urban and yet the knowledge regarding cities and their food dynamics remains paradoxically limited. The information on how cities are fed and how the related waste is managed – the urban food metabolism – is largely dispersed, and most of the data comes from a top-down approach which hides local disparities and asymmetries between the rich and the poor. Ecological implications of intra-urban relationships and international commerce flows have also not been studied duly, and interdisciplinary knowledge gaps remain on food system vulnerabilities to climate change and environmental degradation.
This knowledge gap is problematic because understanding the political economy of food systems is a key prerequisite for appropriate climate-ready policy-making in the urban environment. More understanding is needed on the implications of external forces on food dynamics, the drivers of food security and food sovereignty, and the causes of nutritional food inequalities within urban/rural systems, to name a few themes. Moreover, the medium- and long-term effects of climate change could well shift food production seasons globally, disseminating pests and diseases and modifying the sets of feasible crops for local production and supply.
Changing climate and food
Climate change will certainly have an impact on food productivity and availability in the Americas. The question is how to determine the exact impacts, because the severity of climate change impacts on food systems is hard to predict due to the complexity and uncertainty of crop productivity under new environmental conditions. For example, the North American continental average temperatures are expected to increase 4o Celsius (C) at higher latitudes and 3o C for the continental US, and rainfall might increase in Canada and the Northeastern US but decrease in the Southwestern US and Northern Mexico.
Besides the impacts of repeated and more violent extreme weather events, higher temperatures and changing rainfall patterns may affect both agricultural productivity and water availability. Sea level increases of up to one meter in coastal zones will also have important implications, not only to human safety but also on food production. Low-lying costal agriculture could be inundated, for example, as it is expected throughout Asia.
Climate impacts on fisheries are still uncertain, but will likely shift oceanic fish stocks northward. Temperature changes, sea level rise, and ocean acidification will affect catches – particularly in tropical and subtropical oceans, seas, and lakes – and increase the vulnerabilities of cultured fish. Climate can also exacerbate eutrophication (nutrient loading), causing phytoplankton growth and increasing the frequencies of harmful and toxic algal blooms.
Even if we don’t know exactly how humans will act in the short, medium, and long terms in dealing with climate change implications, anticipatory and adaptive measures can indeed be expected: farms changing locations; shifts in harvest dates; selection of crops with different sensitivities; agro-ecological techniques; irrigation or water harvesting systems; expanded production areas; mixing crops and livestock; diversification of producers’ income through industry or service sectors; and migration.
The social implications of climate change impacts on food systems will ultimately affect food availability and human well-being, particularly for poorer populations, among which children will be the most exposed. Small-scale food producers and their families, who are already struggling to survive, would likely be the first affected, experiencing greater hunger and misery (about 925 million people were still undernourished in 2010: 578 million in Asia and 239 in Sub-Saharan Africa). However, most urban systems will also be disturbed by some degree as well.
The social implications of climate change impacts on food systems will affect food availability and human well-being, particularly the poor.
Cities and food demand
As mentioned, a better understanding of the political economy of food systems is central for robust policy and decision-making, not only because of environmental and climate issues, but also because worldwide rural populations are decreasing and diets are becoming more energy demanding through mounting meat, diary, and pre-processed food intake.
Improvements in crop and livestock production have doubled food production capacity over the last 60 years, while increasing agricultural land by just 10%. Such productivity trends, mainly thanks to intensive fossil-fuel based inputs, will be hard-kept as we approach global peak oil. Gas reserves, an input in the production of nitrogen fertilizer, are also decreasing rapidly. Still, it is believed that by 2050 a 70% increase in agricultural production will be needed to meet business as usual global food demands. In this context, urban food demands are of special concern because urban populations, who have a higher purchasing power, are expanding. Increasing food quantities will need to be brought into cities and distributed throughout expanding urban areas, all within a context of climate change.
If business-as-usual practices are maintained, nations with emerging economies and rapid urbanization will see rising demands and thus some degree of food dependency. At the same time, prospects for feeding fast-growing developing cities do not look favorable, such as in Africa where per capita production of cereals has declined over the last 50 years, or Asia where the population keeps growing and where higher incomes are shifting food preferences and demand.
Thus, a lack of sufficient production capacity, rising energy prices and peak oil, disruptions in food production, and expanding and multi-scaled links of food-chain dependency will certainly be central issues to be dealt with in a changing world.
Urban food metabolism
Urban and peri-urban food production units can supply as much as 85% of the urban basic food requirement, but this is not a clear-cut pattern and changes from city to city. Dependency, however, is clear in most of the cases, and makes the use of metabolic food assessment policy-advantageous.
Such an assessment offers a comprehensive state of energy and material inputs and outputs, in and beyond cities. The analysis encompasses subsystems of production, supply, distribution, consumption, social reproduction, generation/recycling of pollutants, and waste. Flows and stocks can be particularly analyzed from a climate perspective in terms of total direct and indirect production-based and consumption-based emissions.
Inflows and stocks of food urban metabolism cover land-use related aspects, production, uses (and misuses) of water, fertilizers and other agrochemicals, the operation and maintenance of storage, food processing and packaging facilities, transportation, energy, and other inputs and artifacts needed for preserving and cooking food. Besides non-used or final waste outputs, other outflows include food wasted during production: up to a third of total production – about 1.3 billion tons of wasted food annually. At the household level, while inorganic residues and packaging are the major solid outflow, organics usually represent 30-40% of residues and contribute to urban methane emissions.
With every harvest that flows into cities, rural or peri-urban soils export their fertility (mainly phosphorus, potassium and nitrogen), a condition that creates what has been called a negative urban nutrient footprint. At the same time, water demanded for producing food is exported to rural areas, creating an urban virtual water debt.
Organic solid residues and waste can however be seen from a nutrient cycle perspective as an agriculture input. In this sense, in an urban system – where informal settlements are often the public face of food insecurity – urban and peri-urban agriculture are worthwhile options, not only as a source for commodities but also as a factor to reduce environmental burden. Of course, urban agriculture in terms of food provision will be limited for most cases, but urban or peri-urban agriculture can “close” the rural/urban water and nutrient cycles, absorbing urban organic waste and avoiding the use of petroleum-based agrochemicals that demand substantial energy for production.
Adequate policies will be needed to avoid potential environmental and health risks. Several experiments of this kind are already under way or being promoted, mainly in Africa, Central America, and the Caribbean. Where possible and feasible, actions are being initiated by local governments, the International Council for Local Environmental Initiatives (ICLEI), the UN Food and Agricultural Organization (FAO)’s Growing Greener Cities Program, the International Network of Resource Centres on Urban Agriculture and Food Security (RUAF) Foundation, and others.
Climate mitigation and food accessibility
Agriculture accounts for 10-12% of total GHG emissions according to the IPCC, contributing about 47% and 58% of total anthropogenic emissions of CH4 and N2O respectively, both increased by nearly 17% between 1990 and 2005. This is an average annual emission increase of about 60 million tons of CO2 equivalent per year (MtCO2-eq/yr). However, FAO’s estimates for livestock emissions are set at about 18% of total anthropogenic GHG emissions, a disparity that manifests a sharp underestimation of total food sector GHG emissions.
More recent estimations indicate that 14% of global GHG emissions are attributable to agriculture, and between 17-32% when considering land conversion effects. Anthropogenic greenhouse gas emissions from meat, milk, and egg production by 2050, using FAO projection scenarios, are expected to be 39% above of those reported in 2000.
It seems urgent to revisit food system dynamics in order to progressively decuple agriculture from fossil fuels and to develop resilient urban/rural linkages with regard to shocks and challenges from climate change, natural disasters, and social conflicts, or even international market disruptions and potential soaring food prices. Being able to respond means planning for more locally integrated and diverse production capacity, which for urban systems globally implies a profound paradigm shift. This is particularly true for some developed countries, where the energy used in getting food to the plate can be several times larger than its production.
Even more, since nations with prosperous economies and rapid urbanization might demand more food, particularly meat, dairy products, and pre-processed foods, it is central to realize that this type of food implies not only lower nutrient content but also a more energy-intensive and land-demanding production.
While animal calories already represent up to a third of total available calories in developed regions, emerging economies such as China have increased such type of consumption up to five times between 1961 and 2007, leading a global demand for animal products that has already produced up to 50% of total land demand and change during that same time.
Because of the above, it is evident that changing diet can certainly help mitigate climate change, and even more, it might be an essential response. Meat production costs are high in terms of the amount of feed required per kilogram of final product: it takes 9 kilograms (kg) of feed to make 1 kg of chicken meat; about 14 kg of feed per kg of pig meat; and 20 kg of grain per kg of beef. The infographic below illustrates the direct and indirect emissions and water footprints of various sectors and products.
Growing demand for meat, expected to be between two and three times its current levels, means greater pressure on productivity and land demand. It should be noted, though, that meat and diary consumption worldwide is uneven. While in US the per capita consumption of meat is estimated at about 100 kg per year, in India it is less than 6 kg yearly.
Long-term sustainable food
Current practices have not only contributed to environmental degradation, land dispossession and concentration, and oligopoly control of food production, technologies, and entire food chains, but also to malnutrition, lack of proper nutrients, over consumption, and obesity.
Food sovereignty has been proposed as a sustainable alternative in socio-ecological and cultural terms. It embraces, among other aspects, localized agro-ecological practices and well-informed, voluntary changes to diet in line with traditional culinary knowledge and good practices. Sustainable food politics will need numerous transition pathways to help to reverse uneven development, environmental degradation, and anthropogenic climate change. Transition involves a diversity of temporal and space scales, long-term integral planning, and concrete localized social actions that in turn demand greater democracy and ample participatory processes.
In addition, any evaluation of the ways in which urbanization and climate change may affect food demand and supply must take into account the complex linkages between rural and urban systems. Special attention should be given to the interactions between particular geographical regions and social categories, as climate change impacts will affect both systems and with a larger impact on low-income groups.
In short, socio-economic inequalities and vulnerabilities, the structure of spatial disparities, and the potential conflicts between urban groups and between urban and rural spaces must be acknowledged and recognized as key issues in long-term food supply (in)security within changing climate and environmental contexts.
Gian Carlo Delgado Ramos works at the Interdisciplinary Research Center on Sciences and Humanities of the National Autonomous University of Mexico, and is member of the National System of Researchers of CONACYT-Mexico.