Environmental impacts of genetically modified (GM) crop use 1996–2018: impacts on pesticide use and carbon emissions

Abstract

This paper updates previous assessments of the environmental impacts associated with using crop biotechnology (specifically genetically modified crops) in global agriculture. It focuses on the environmental impacts associated with changes in pesticide use and greenhouse gas emissions arising from the use of GM crops since their first widespread commercial use 22 years ago. The adoption of GM insect resistant and herbicide tolerant technology has reduced pesticide spraying by 775.4 million kg (8.3%) and, as a result, decreased the environmental impact associated with herbicide and insecticide use on these crops (as measured by the indicator, the Environmental Impact Quotient (EIQ)) by 18.5%. The technology has also facilitated important cuts in fuel use and tillage changes, resulting in a significant reduction in the release of greenhouse gas emissions from the GM cropping area. In 2018, this was equivalent to removing 15.27 million cars from the roads.

The climate benefits of yield increases in genetically engineered crops

“…This assumption is reasonable, as insect pests and weeds cause separate yield damage, and farmers make decisions about insecticide and herbicide sprays independently. In their global analysis of GE crop impacts, Brookes and Barfoot (2020) also added the benefits of stacked IR and HT traits. As an additional robustness check, we calculate total avoided emissions using a lower value for the yield benefit of stacked traits — just the yield benefit from the IR trait, rather than adding the effects from IR and HT traits.…”

“…We used the default CO 2 e/N input, and we did not input values for rice methane. Site-specific changes in fuel use could also incorporate decreases due to reduced tilling and pesticide application, as calculated by Brookes and Barfoot (2020).…”

“…Previous studies quantified the economic benefits of GE crops, including increases in crop yields and profits, as well as the environmental and health benefits resulting from reduced pesticide use 1,2 . Lower GHG emissions from reduced tillage and savings in the use of tractor fuel were also considered 3 . However, reductions in GHG emissions associated with yield increases in GE crops were not quantified.…”

Genetic Variation and Unintended Risk in the Context of Old and New Breeding Techniques

“…To put this in perspective, in order to maintain current agricultural production outputs without "GM" crops, nearly 25 million hectares of additional arable land would need to be cultivated worldwide (Qaim, 2016). The adoption of "GM" crops has also led to positive health (Smyth, 2020) and environmental impacts, including reductions in the amount of chemicals applied, as well as a decrease in fuel use and facilitation of reduced-tillage practices, which minimizes erosion and greenhouse gas emissions (Brookes and Barfoot, 2020b;Qaim, 2020).…”

Genetically Modified Potato for Pest Resistance: Thrift or Threat?

“…The development of insect resistant GM crops resulted in reduction of insecticides by 775.4 million kg (8.3%) and decreased the environmental impact of these chemicals by 18.5%. By cutting fuel usage associated with the production of chemical spray runs and tillage, this technology also reduced carbon dioxide emissions equivalent to removing more than 15 million cars from the roads [4]. However, wider adoption of GM crops remains the subject of biosafety concerns due to potential risks such as gene flow, evolution of resistance in insects and weeds, adverse effects on beneficial non-target organisms, or toxicity and allergenicity to humans.…”