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Purdue studies climate impacts of a GMO ban

A GMO seed trial on
the island of Kauai.
Photo by Joan Conrow

Eliminating GMO commodity crops in America would significantly boost greenhouse gas [GHG] emissions and have other environmental and economic impacts, according to a new study by Purdue University agricultural economists.

“GMOs have gotten a lot of bad press, so it made sense to us to ask the question of what would be the economic and greenhouse gas emission impacts if they were banned in the U.S.,” Dr. Wallace E. Tyner, the James and Lois Ackerman Professor in Purdue's Department of Agricultural Economics, told the Alliance for Science.

"This is not an argument to keep or lose GMOs," Tyner said. "It's just a simple question: What happens if they go away?"

The Purdue researchers found that yields of soy, corn, and cotton would decrease, requiring some 252,047 acres of U.S. forest and pasture lands to be converted to crop production to offset the shortfall. A reduction in the export of U.S. commodity crops would also increase demand for cropland in other nations.

“Our analyses confirms that if we do not have access to the GMO technology, a significant amount of land would need to be converted from other crops, cropland pasture, pasture, and forest to meet the global food demand. This could cause deforestation in U.S. and other regions to satisfy higher demand for cropland, which leads to expansion in GHG emissions due to land use changes,” according to the paper's abstract.

“Some of the same groups that oppose GMOs want to reduce greenhouse gas emissions to reduce the potential for global warming," Tyner said. "The result we get is that you can't have it both ways. If you want to reduce greenhouse gas emissions in agriculture, an important tool to do that is with GMO traits."

In 2014, 18 million farmers in 28 countries planted more than 181 million hectares of GMO crops, with the U.S. accounting for 40 percent of the global share. In the U.S. in 2014, GM crops accounted for 94% of soybeans, 91% of cotton, and 89% of the corn produced.

Though GMO crops have always been controversial, the paper noted, “More recently there has emerged increased opposition against GMO crops. Given that the GMO crops have been widely produced and used in U.S. and also exported to other countries, and that the GMO crops are usually more productive than the non-GMO crops, imposing restriction on production and/or consumption of these crops could lead to: lower crop production on the existing cropland base as yields drop; reduction in the net exports of U.S. agricultural products; higher crop prices at the national and global scales; some increases in food prices; drops in farm incomes and farmland values; and increases in use of pesticides and other inputs required without GMO traits (not examined in this paper). These impacts jointly harm the US and global economy and generate welfare losses.”

Lower crop yields would also result in higher commodity prices. Corn prices would increase as much as 28 percent and soybeans as much as 22 percent, according to the study. The resulting higher food prices would cost American consumers an extra $14 billion to $24 billion per year.

"If in the future we ban GMOs at the global scale, we lose lots of potential yield," said study co-author Farzad Taheripour, a research associate professor of agricultural economics at Purdue. "If more countries adopt GMOs, their yields will be much higher.”

To conduct their analysis, the researchers first surveyed the scientific literature to obtain a range of estimates on yield losses associated with losing GMO traits in the U.S. To quantify the land use and economic impacts, they then fed those estimates into the Purdue-developed GTAP-BIO model, which has been frequently used to examine the economy-wide impacts and land use consequences of agricultural, energy, trade and environmental policies.

The researchers have now collected data on global GMO usage and penetration by crop and country and will be using a similar approach to estimate the impacts of a global ban, Tyner said. The global study also will look at current levels and possible future levels of GMOs if the global penetration level were to expand.

Harry Mahaffey, an agricultural economics graduate student, also participated in the research. Their findings were presented at the International Consortium on Applied Bioeconomy Research in Ravello, Italy, last year, and will be published in the journal AgBioForum.

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