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New published research paper - Environmental impacts of genetically modified (GM) Crop use 1996–2016: Impacts on pesticide use and carbon emissions

Published on: 12th July 2018
Published By Graham Brookes & Peter Barfoot

This paper updates previous assessments of the environmental impacts associated with using crop biotechnology 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 over 20 years ago. The adoption of GM insect resistant and herbicide tolerant technology has reduced pesticide spraying by 671.4 million kg (8.2%) 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 18.4%. 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 2016, this was equivalent to removing 16.7 million cars from the roads.

View abstract on publishers website -​

Keywords - GMO, active ingredient, biotech crops, carbon sequestration, environmental impact quotient, no tillage, pesticide

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GM crop technology has been widely used for over 20 years in a number of countries and is mainly found in the four crops of canola, maize, cotton and soybean. In 2016, crops containing this type of technology accounted for 48% of the global plantings of these four crops. In addition, small areas of GM sugar beet (adopted in the USA and Canada since 2008), papaya (in the USA since 1999 and China since 2008), alfalfa (in the US initially in 2005–2007 and then from 2011), squash (in the USA since 2004), apples (in the USA since 2016), potatoes (in the USA since 2015) and brinjal (in Bangladesh since 2015) have been planted.

The main traits so far commercialised convey:

  • Tolerance to specific herbicides (notably to glyphosate and to glufosinate) in maize, cotton, canola (spring oilseed rape), soybean, sugar beet and alfalfa. This GM Herbicide Tolerant (GM HT) technology allows for the ‘over the top’ spraying of GM HT crops with these specific broad-spectrum herbicides, that target both grass and broad-leaved weeds but do not harm the crop itself;

  • Resistance to specific insect pests of maize, cotton, soybeans and brinjal. This GM insect resistance (GM IR), or ‘Bt’ technology offers farmers resistance in the plants to major pests such as stem and stalk borers, earworms, cutworms and rootworm (eg, Ostrinia nubilalis, Ostrinia furnacalis, Spodoptera frugiperda, Diatraea spp, Helicoverpa zea and Diabrotica spp) in maize, bollworm/budworm (Heliothis sp and Helicoverpa) in cotton and caterpillars (Helicoverpa armigeru) in soybeans. Instead of applying insecticide for pest control, a very specific and safe insecticide is delivered via the plant itself through ‘Bt’ gene expression.

In addition, the GM papaya and squash referred to above are resistant to important viruses (eg, ringspot in papaya), the GM apples are non-browning and the GM potatoes (planted in 2016) have low asparagine (low acrylamide which is a potential carcinogen) and reduced bruising.

This paper presents an assessment of some of the key environmental impacts associated with the global adoption of these GM traits. The environmental impact analysis focuses on:

  • Changes in the amount of insecticides and herbicides applied to the GM crops relative to conventionally grown alternatives and;

  • The contribution of GM crops towards reducing global Greenhouse Gas (GHG) emissions.

It is widely accepted that increases in atmospheric levels of greenhouse gases such as carbon dioxide, methane and nitrous oxide are detrimental to the global environment (see for example, Intergovernmental Panel on Climate Change (2006)). Therefore, if the adoption of crop biotechnology contributes to a reduction in the level of greenhouse gas emissions from agriculture, this represents a positive development for the world.

The study integrates data for 2016 into the context of earlier developments and updates the findings of earlier analysis presented by the authors (eg, Brookes and Barfoot (2017).

The methodology and approach in this present discussion are unchanged to allow a direct comparison of the new with earlier data. Readers should however, note that some data presented in this paper are not directly comparable with data presented in previous analysis because the current paper takes into account new data (including revisions to data for earlier years). Also, in order to save readers the chore of consulting earlier papers for details of the methodology and arguments, these elements are included in full in this updated paper.

The aim has been to provide an up to date and as accurate as possible assessment of some of the key environmental impacts associated with the global adoption of GM crops. It is also hoped the analysis continues to make a contribution to greater understanding of the impact of this technology and facilitates more informed decision-making, especially in countries where crop biotechnology is currently not permitted.

Graham Brookes & Peter Barfoot: 12th Jul 2018 10:32:00


Asian Farmers Would See Annual Weed Control Costs Increase By $1.4 To $1.9 Billion Due To Potential Restrictions On Glyphosate Use, New Study Reports

A new paper published in the journal Agbioforum (1) points to higher weed control costs, less effective weed control, more difficult access to fields and lower yields, if farmers in seven Asian countries could no longer use glyphosate. The peer reviewed paper written by Graham Brookes of PG Economics Ltd examined the current use of glyphosate, the reasons for its use and what changes farmers would make to their weed control programs if glyphosate was no longer available for use. Seven countries were included in the study – Australia, China, India, Philippines, Indonesia, Vietnam and Thailand – as these were representative of countries where glyphosate use in agriculture is significant, countries that may be considering use restrictions for glyphosate and countries were farmers are planting glyphosate tolerant crops.

Uk Urged To ‘bring Back’ Sound Science As The Basis For Regulating Crop Genetic Innovations Post-brexit

‘UK plant genetics: a regulatory environment to maximise advantage to the UK economy post Brexit’ considers three future scenarios for the regulation of gene edited crops and genetically modified organisms (GMOs), ranging from maintaining current alignment with the EU through improved implementation of EU rules, to the UK setting its own regulatory path on both GMOs and NBTs.

New Published Research Paper - Environmental Impacts Of Genetically Modified (gm) Crop Use 1996–2016: Impacts On Pesticide Use And Carbon Emissions

New published research paper - Environmental impacts of genetically modified (GM) Crop use 1996–2016: Impacts on pesticide use and carbon emissions - GMO, active ingredient, biotech crops, carbon sequestration, environmental impact quotient, no tillage, pesticide

Biotech Crop Adoption Leads To Greater Sustainability And Socioeconomic Opportunities For Global Farmers And Citizens

The complementary studies – PG Economics’ “GM Crops: Global Socio-Economic and Environmental Impacts 1996-2016” and ISAAA’s “Global Status of Commercialized Biotech/GM Crops: 2017” – examine the continued widespread adoption of global crop biotechnology, and the significant positive socio-economic and environmental impacts of this adoption by farmers and communities around the globe.