By John Reilly | MIT Joint Program on the Science and Policy of Global Change
According to United Nations experts, enough food is produced around the globe to enable everyone to be adequately nourished and lead healthy and productive lives. And yet, approximately 926 million people continue to go hungry, especially the rural poor in developing countries. The reasons for this are manifold, ranging from natural disasters and extreme storms to war and poverty. Identifying and implementing viable solutions to the problem will become even more urgent over the next 35 years, as the global population soars from today’s 7.3 billion to an estimated 9-10 billion, and the demand for food is expected to more than double.
Agriculture faces the challenge of meeting that demand even as it must reduce its environmental footprint and adapt to a changing environment. As it stands now, the Earth’s atmosphere and waterways are on the front line, and climate change, tropospheric ozone, and water availability are threats to continued growth in yields.
Land use and agriculture (including forestry) account for an estimated 24% of planet-warming greenhouse gas emissions (although land sequestration offsets an estimated 1/5 of that total). Land-use change is an important source of carbon dioxide, although when properly managed, it could be a sink. The agriculture sector is the biggest contributor of nitrous oxide (largely from fertilizers) and methane (primarily from rice cultivation, ruminants and manure management), accounting for an estimated 85% and 50%, respectively, of emissions of these gases from human activities.
In addition, soil erosion resulting from crop cultivation, along with the nutrients carried with it, has degraded water quality in streams, lakes and coastal waters. In the U.S., the Gulf of Mexico and Chesapeake Bay are among the most seriously impacted coastal ecosystems. Nitrate contamination of groundwater from fertilizer use is also a concern. As efforts proceed to reduce these impacts, agricultural practices will need to adapt.
On the other side of the ledger, climate change and increasing levels of tropospheric ozone will continue to threaten future yields unless global emissions are brought under control. While warming may advantage areas limited by cold temperatures, extreme heat and drought are likely to increase the frequency of major crop failures. Tropospheric ozone damages the leaves of crops, especially at early stages of growth, and is already estimated to reduce yields by 10-12% in China, and somewhat less in the U.S. and Europe. Increasing competition for water resources as population and economic activity expand, combined with changing precipitation and snowpack, will affect water availability for irrigation, even as higher temperatures increase crop water needs. While warming speeds up the hydrological cycle—meaning more rainfall—computer model simulations show increased water stress in most important agricultural regions of the world.
Evaluation of land resources by the U.N.’s Food and Agriculture Organization suggest availability of arable land itself is not a major constraint on food production at least through mid-century, assuming continued yield improvements. There are, however, some wild cards that could vastly impact agriculture in the coming decades. Among these are more ambitious policies to stabilize the climate, large-scale production of biomass energy, and major incentives for carbon sequestration in forests.
Since energy is an important input to agriculture, a global shift away from fossil fuels is likely to boost energy costs and thus make agricultural production more expensive. In addition, the space requirements for biomass energy and re-growing forests to sequester carbon could cut into the amount of land available for crops and livestock production. Agriculture will need to continue to intensify use of available land, getting more output from less land, while at the same time reducing the environmental impacts of the more intensive land-use practices.
Other long-term forces affecting agriculture include the industrialization of agriculture; technological advances; specialization or diversification of farming systems; reliance on a global or local food supply; and the use of land and waterways for urbanization, recreation and ecosystem protection. While some of these forces may make the job of feeding the world more difficult, technology that improves yields and limits vulnerability to environmental change, delivers nutrients efficiently and reduces food waste can hopefully overcome the challenges. At the same time, successful efforts to control climate change and ozone pollution will lessen the adaptation agriculture will need to make. More diversification of farming systems and well-developed international markets can further limit vulnerabilities to local droughts and disasters. And while new technology is certainly welcome, if not essential, adopting today’s best practices worldwide can take us a long way.
A version of this essay was presented at Cargill’s Minneapolis headquarters on Dec 16, 2015 to invited agriculture industry, university and NGO participants. See presentation video here. A global producer of food, agriculture, financial and industrial products, Cargill is a signatory to the 2014 United Nations' New York Declaration on Forests, in which the company committed to helping cut natural forest loss in half by 2020, and end it by 2030.