Banning glyphosate may lower crop yield, increase carbon impact

A study published in the journal GM Crops & Food assesses the potential economic and environmental impacts that would arise if restrictions on glyphosate use resulted in the world no longer planting genetically-modified herbicide tolerant (GM HT) crops. GM HT crops have been grown on a widespread commercial basis since 1996, and in 2015, the global cultivation reached 147.9 million hectares, a 200-fold increase from the 1996 level of 0.7 million hectares. The number of countries adopting biotech HT crop cultivation has also increased from three in 1996 to 13 in 2015, with the United States leading the way in the use of this technology in crop production and accounting for 43% of total plantings in 2015.

According to the researchers, the “first round” impact of a glyphosate ban on the usage of GM HT crops would, in effect, “undo” the farm level benefits arising from the use of this technology. There would be an annual loss of global farm income gains of $6.76 billion and lower levels of global soybean, corn, and canola production equal to 18.6 million tons, 3.1 million tons, and 1.44 million tons, respectively.

There would be an annual environmental loss associated with a net increase in the use of herbicides of 8.2 million kg of herbicide active ingredient (+1.7%), and a larger net negative environmental impact, as measured by the environmental impact quotient indicator of a 12.4%. Also, there would be additional carbon emissions arising from increased fuel usage and decreased soil carbon sequestration, equal to the equivalent of adding 11.77 million cars to the roads.

Global welfare impacts based on these farm level impacts (identified through use of the Computable General Equilibrium model GTAP-BIO) point to global production of soybeans and rapeseed falling by 3.7% and 0.7%, respectively, partially offset by increases in other oilseeds (notably palm oil). World prices of all grains, oilseeds, and sugar are expected to rise, especially soybeans (+5.4%) and rapeseed (+2%). The welfare impacts are mostly negative, with global welfare falling by $7.4 billion per year. Land use changes will arise, with an additional cropping area of 762,000 hectares, of which 53% derives from new land brought into cropping agriculture, including 167,000 hectares of deforestation. These land use changes are likely to induce the generation of an additional 234,000 million kg of carbon dioxide emissions.

Study