Genetically modified crops and sustainability: 25 years after their large-scale introduction, yields are higher and the environmental footprint is lower

gGenetically modified (GM) crops have increased global production of food, feed and fiber by nearly one billion tonnes (1 tonne equals 1.10231 tonnes) since their introduction in 1996. Farmers who grow these crops have also reduced the environmental footprint associated with their crop protection practices by over 17% according to my peer-reviewed research published in October1.2.

The research focused on farming practices with GM crops between 1996 and 2020 and the socio-economic and environmental impact associated with pesticide use.

By increasing crop yields, technology has reduced the pressure to bring new land into agriculture. This is vital if the world is to succeed in feeding a growing population without resorting to practices such as deforestation. It is also crucial for maintaining and restoring the natural habitats and vegetation that are best suited for many species of plants and animals and are essential for storing carbon.

How GM technology increased production

GM crop technology has increased yields primarily through better pest and weed control. Insect resistant (IR) cultivation technology used for cotton and maize has, between 1996 and 2020, for all users of this technology, increased yields on average by 17.7% for IR maize and by 14. 5% for IR cotton compared to conventional production systems. Farmers who grow IR soybeans commercially in South America have seen an average 9.3% increase in yields since 2013.

IR maize genetically modified to resist insects

The impact of higher yields on production has been considerable. It has resulted in additional global production of 330 million tonnes of soybeans, 595 million tonnes of corn, 37 million tonnes of cotton lint, 15.8 million tonnes of canola and 1.9 million tonnes of sugar beets since 1996.

This allows farmers to grow more without needing to use additional land. For example, if plant biotechnology had not been available to farmers in 2020, maintaining global production levels that year would have required the planting of an additional 11.6 million hectares (ha — 1 hectare equals 2.4711 acres) of soybeans, 8.5 million hectares of corn, 2.8 million hectares of cotton and 0.5 million hectares of canola. This total of 23.4 million hectares is equivalent to the combined agricultural area of ​​the Philippines and Vietnam.

Environmental footprint

GM crop technology has also helped farmers who grow these crops reduce the environmental impact associated with their crop protection practices. Over the 25-year period from 1996 to 2020, plant biotechnology reduced the application of crop protection products by 748.6 million kilograms, an overall reduction of 7.2% in planted area in GM crops. This is equivalent to 1.5 times the total annual use of plant protection products in China. As a result, farmers growing GM crops reduced the environmental impact associated with their crop protection practices by 17.3%, as measured by an indicator known as the Environmental Impact Quotient (EIQ).3.


This reduction in pesticide use has been largely due to crops modified to be tolerant to specific herbicides (HT) to facilitate better weed control and crops resistant to a range of insect crop pests (IR) that otherwise damage crops or generally require application. insecticides to control them.

The greatest share of the reduction in terms of the amount of pesticide active ingredients applied was accounted for by GM IR cotton (45%) followed by GM HT maize (30%).

Share of global active ingredient use (reductions) by trait 1996-2020 (baseline total 748.6 million kg)


In terms of the environmental impact associated with the use of herbicides and insecticides on these crops, as measured by the EIQ indicator, the greatest share of these improvements has also been made by GM IR cotton, at approximately 40% of the total, followed by GM HT soy. (26%).

Share of aggregate QIS changes (improvements) by trait 1996-2020


At the country level, US farms experienced the most significant environmental improvements, with a 322 million kg reduction in pesticide active ingredient use, or 43% of the total. This is not surprising given that US farmers were the first to widely use GM crop technology and since the early 2000s, GMO adoption levels in these four US crops have exceeded 80%. Furthermore, the use of insecticides/herbicides was, before the availability of GM crop technology, the main method of controlling weeds and pests.

The widespread adoption of IR cotton in China and India has also resulted in a reduction in the use of insecticidal active ingredients between 1996 and 2020 of over 304 million kg.


There have been some problems associated with GM crops, but they are manageable. Excessive use of glyphosate with TH crops by farmers, especially in the early years after the introduction of the technology, has contributed to the development of weed resistance. As a result, farmers have over the past 20 years adopted more integrated weed management strategies incorporating a mix of herbicides and non-herbicide weed control practices. These changes reduced the magnitude of the initial environmental gains associated with changes in herbicide use.

In addition, the magnitude of carbon emissions savings each year associated with the facilitating role of GM HT crops in the adoption of no-till and reduced-tillage systems has likely diminished, with some farmers returning to tillage in the framework of weed management practices to control herbicide tolerant weeds.

Overall, these results are consistent with the analysis of other researchers such as the global meta-analysis by Klumper W and Qaim M in 20144 and the United States-specific analysis of Fernando-Cornejo J, et. al., also in 20145.

The adoption of GM herbicide-tolerant (HT) crop technology continues to generate net environmental gains and, when combined with GM IR technology, continues to provide substantial net environmental benefits.


  1. Brookes G. Use of genetically modified crops, 1996-2020: Environmental impacts associated with changing pesticide use. 2022. GM Crops and Foods, 13, Issue 1. DOI: 10.1080/21645698.2022.211849.
  2. Brooke G. Impacts on farm incomes and production from the use of GM crop technology 1996-2020. 2022. DOI: 10.1080/21645698.2022.2105626.
  3. Kovach J. Petzoldt C. Degni J. Tette J. A method to measure the environmental impact of pesticides. New York Food and Life Sciences Bulletin. NYS Agriculture. Exp. Sta. Cornell University, Geneva, NY, 139. 8 pp. 1992 and updated annually. Available on the global web:
  4. Klumper W and Qaim M. A meta-analysis of the impacts of genetically modified crops. PLOS One. 2014.
  5. Fernandez-Cornejo J, Wechsler S, Livingston M, and Mitchell L. Genetically modified crops in the United States. 2014. USDA Economic Research Service ERR report 162.

Graham Brookes, agricultural economist with PG Economy, UK, has over 35 years of experience analyzing the impact of technology use and policy change in agriculture, and has authored numerous journal articles at peer-reviewed on the impact of regulation, policy change and GM crop technology. E-mail: [email protected]

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