Meeting the growing demand for food and other agricultural products is one of the most daunting challenges we face today. At the same time, clearing forests and grasslands for farming releases carbon into the atmosphere, fueling climate change, a similarly alarming and expensive problem.
A study published today by University of Minnesota researchers in Proceedings of the National Academy of Sciences found that limiting agricultural expansion to several key global regions could meet the predicted need to double food production by 2050 while preserving nearly 6 billion metric tons more carbon than would be safeguarded with unguided expansion. Preserving this much carbon is worth approximately $1 trillion in terms of climate change mitigation.“To meet the large projected increases in food demand, it is likely that a significant amount of natural land will be converted to agricultural production,” said lead author Justin Andrew Johnson, an economist with the Natural Capital Project at the University’s Institute on the Environment. “Converting natural lands, such as forests and grasslands, incurs large costs through losses of carbon storage and other ecosystem services.”
To find the regions in which crop expansion would have the highest calorie gains for a given increase in carbon footprint, the researchers analyzed high-resolution geospatial data from approximately 10 million locations around the world in search of prospective croplands that produce the most calories relative to the amount of carbon stored, called the crop advantage. They looked at 175 different crops and valued production of consumable calories rather than dry weights to reflect the real goal of food production. They valued the carbon storage potential of each area using the social cost of carbon, an estimate used in economics that monetizes the damages carbon contributes to the economy. The higher the crop advantage, the higher the calorie potential and the better the trade-off for lost carbon storage due to cultivation.
Areas with the highest crop advantage include the U.S. Corn Belt, parts of Western Europe, the Nile Valley, the Ganges River Plain and eastern China. Although these regions are already heavily farmed, the researchers found that expanding farmlands at the edges could produce more calories while limiting carbon loss relative to expansion in other parts of the world.
Parts of Eastern Europe, the Ukraine, Russia and several pockets in Southeast Asia also showed potential for agricultural expansion; tropical regions such as the Philippines, Indonesia, Southern India, parts of sub-Saharan Africa and Central America were found to have a low crop advantage. “There are high costs with developing agriculture in the tropics, and we need to consider them,” Johnson said.
“Careful consideration of both carbon storage and crop yield can maximize carbon storage while meeting agricultural production goals,” the researchers concluded in the paper. “Moving closer to desirable outcomes requires attention to institutional, political, social and economic factors, because billions of people must change what they are doing. These changes will require recognition by political leaders and the general public of the value of carbon storage (and other ecosystem services). Otherwise, there will be little push for carbon policies such as establishing a price for carbon storage and therefore little incentive for landowners to incorporate carbon or the value of other ecosystem services into their decision-making.”
This research was conducted at the University of Minnesota in partnership with the Natural Capital Project and the Global Landscapes Initiative with funding support from The Nature Conservancy. Other authors on the paper are C. Ford Runge, Benjamin Senauer and Stephen Polasky of the University’s College of Food, Agricultural and Natural Resource Sciences and Jonathan Foley, formerly of the College of Biological Sciences. Runge and Polasky are resident fellows and Jonathan Foley is former director of the Institute on the Environment.
Johnson and colleagues are expanding this research to include other ecosystem services such as biodiversity preservation, water quality protection and soil retention, along with the monetary costs and benefits to farmers of expansion and yield increases.
The University of Minnesota’s Institute on the Environment seeks lasting solutions to Earth’s biggest challenges through research, partnerships and leadership development. For more information, visit environment.umn.edu.
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