This article seeks to quantify the economic and environmental impacts of genetically modified (GM) crops worldwide, since the first such strains were commercialised. The authors, two agricultural economists from the United Kingdom, look at three dimensions in particular: the effects on farm incomes, changes in insecticide and herbicide use, and the associated changes in carbon dioxide (greenhouse gas) emissions into the atmosphere.

The authors claim to show that GM crops have led to substantial benefits in terms of farm incomes and reductions in pesticide spraying and carbon dioxide emissions from agriculture. However, herbicide tolerant GM crops have meant farmers need to till less and have led to an increase in herbicide applications in some countries.

The authors drew on data from various studies on the impacts of different types of GM crops in different countries. The analysis relies on highly aggregated data and simplified assumptions in order to arrive at broad averages that include countries and agricultural systems which are, in reality, very different. Nevertheless, the article represents a useful contribution to the debates about the impacts of GM crops since they were first commercialised. The authors call for further research into the dynamic, less-tangible and indirect economic impacts of GM crops.

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