Search PG Economics

Use the search below to search our website, if you can't find what you're looking for then contact us and we will do our best to help you.



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

Download PDF Copy -​


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


What Is (risk) Appropriate Regulation Of Gene Editing Technology?

Despite the much-hyped expectation that Europe was on course to follow other parts of the world in removing GMO-style regulatory requirements from gene edited (GE) crops, with EU elections looming and no agreement in sight the bloc now risks slipping back towards precautionary inertia. Summarising their recent peer-reviewed paper exploring risk-appropriate regulation for gene editing, agricultural economists Graham Brookes and Stuart Smyth warn that we must learn the lessons from past experience of divergent international regulation of agricultural innovations. The impact of over-precautionary EU regulation of gene editing will not only disadvantage European agriculture, but will also compromise global efforts to address urgent climate, biodiversity and food security challenges, they argue.

Feeding The Uk Sustainably: Time For Policy Inaction To End

As Ministers prepare to unveil a new land use framework for England this autumn, the scientific evidence behind land sparing as the most effective farm policy for delivering food production, climate and biodiversity goals is compelling. Why then does the UK government continue to favour a land sharing approach through its environmental land management schemes? The recent ‘re-interpretation’ of an expert land use report for the large, land-owning NGOs who commissioned it may provide some clues, writes agricultural economist Graham Brookes.

European Court Ruling On Neonicotinoids Further Highlights Muddle Created By Ongoing Eu Regulatory Inconsistency And Dysfunction

The recent Court of Justice of the European Union (CJEU) ruling that EU Member States can no longer grant derogations (exemptions) for the use of neonicotinoid seed treatments to control pests in arable crops like sugar beet and oilseed rape raises a number of important questions and highlights the regulatory inconsistency and muddle that the European Union (EU) has created for itself

Feeding The World Sustainably: Crop Biotechnology Continues To Make A Significant Contribution, Concludes New Research

GM crop technology continues to make an important contribution to reducing the environmental footprint of agriculture and securing global food supplies in a sustainable way. It has reduced pressure to bring new land into agriculture, which is vital if the world is to maintain and restore the natural habitats and vegetation that are best for many species of plants and animal life and for storing carbon” said Graham Brookes, director of PG Economics, author of the research.