Selected readings

• The 10 Minor Realizations That Flipped My Thinking About GMOs
• GMOs: An Introduction
• On So-Called “Superweeds”
• Answering the 3 Most Common Internet Objections to GMOs
• About Those Industry Funded GMO Studies . . .
• 17 Questions about Glyphosate
• Glyphosate and Cancer: What does the data say?

Environmental Impacts of GE Crops

The environmental impacts of Bt and RoundUp Ready crops have been unequivocally good relative to the most likely counter-scenario.Some stats from Brookes and Barfoot’s “GM crops: global socio-economic and environmental impacts 1996- 2014” (2016) [PDF]

Since 1996, the use of pesticides on the GE crop area was reduced by 640,883 tons of active ingredient (8.2% reduction), and the environmental impact associated with herbicide and insecticide use on these crops, as measured by the EIQ indicator, fell by 18.5%.
Bt cotton has contributed a 43% reduction in the total volume of active ingredient used on GE crops (-249.1 million kg active ingredient, equivalent to a 27.9% reduction in insecticide use on the Bt cotton area) and a 36% reduction in the total field EIQ indicator measure associated with GE crop use (1996-2014) due to the significant reduction in insecticide use that the technology has facilitated, in what has traditionally been an intensive user of insecticides. Similarly, the use of Bt technology in maize has led to important reductions in insecticide use (79.7 million kg of active ingredient), with associated environmental benefits.
The volume of herbicides used in GE maize crops also decreased by 235,000 tons (1996-2014), an 8.4% reduction, whilst the overall environmental impact associated with herbicide use on these crops decreased by a significantly larger 12.6%. This highlights the switch in herbicides used with most GE herbicide tolerant (HT) crops to active ingredients with a more environmentally benign profile than the ones generally used on conventional crops.
Important environmental gains have also arisen in the soybean and canola sectors. In the soybean sector, whilst herbicide use increased by 5.5 million kg (1996-2014), the associated environmental impact of herbicide use on this crop area decreased (improved) by 14.1%, due to a switch to more environmentally benign herbicides. In the canola sector, farmers reduced herbicide use by 21.8 million kg (a 17.2% reduction) and the associated environmental impact of herbicide use on this crop area fell by 29.3% (due to a switch to more environmentally benign herbicides).

Impacts on Greenhouse Gas Emissions

Reduced fuel use from less frequent herbicide or insecticide applications and a reduction in the energy use in soil cultivation. The fuel savings associated with making fewer spray runs (relative to conventional crops) and the switch to conservation, reduced and no-till farming systems, have resulted in permanent savings in carbon dioxide emissions. In 2014, this amounted to about 2641 tons (arising from reduced fuel use of 898 million litres). Over the period 1996 to 2014 the cumulative permanent reduction in fuel use is estimated at 24,000 tons of carbon dioxide (arising from reduced fuel use of 8,124 million litres);
The use of ‘no-till’ and ‘reduced-till’ farming systems. These production systems have increased significantly with the adoption of RoundUp Ready crops because the RoundUp Ready technology has improved farmers’ ability to control competing weeds, reducing the need to rely on soil cultivation and seed-bed preparation as means to getting good levels of weed control. As a result, tractor fuel use for tillage is reduced, soil quality is enhanced and levels of soil erosion cut. In turn more carbon remains in the soil and this leads to lower GHG emissions. Based on savings arising from the rapid adoption of no till/reduced tillage farming systems in North and South America, an extra 5,449 million kg of soil carbon is estimated to have been sequestered in 2014 (equivalent to 19,998 million kg of carbon dioxide that has not been released into the global atmosphere). Cumulatively, the amount of carbon sequestered is likely to be higher due to year-on- year benefits to soil quality; however, it is equally likely that the total cumulative soil sequestration gains are not the sum of each individual year’s estimated saving because only a proportion of the crop area will have remained in permanent no-till and reduced tillage. It is not possible to confidently estimate cumulative soil sequestration gains that take into account reversions to conventional tillage because of a lack of data. Consequently, our estimate of 186,945 million kg of carbon dioxide not released into the atmosphere for the cumulative period 1996-2014 should be treated with caution.Placing these carbon sequestration benefits within the context of the carbon emissions from cars,
In 2014, the permanent carbon dioxide savings from reduced fuel use were the equivalent of removing 1.07 million cars from the road;
The additional probable soil carbon sequestration gains in 2014 were equivalent to removing 8.89 million cars from the roads;
In total, in 2014, the combined GE crop-related carbon dioxide emission savings from reduced fuel use and additional soil carbon sequestration were equal to the removal from the roads of 9.95 million cars, equivalent to 34% of all registered cars in the UK;
It is not possible to confidently estimate the probable soil carbon sequestration gains since 1996. If the entire GE HT crop in reduced or no tillage agriculture during the last twenty years had remained in permanent reduced/no tillage then this would have resulted in a carbon dioxide saving of 186,945 million kg, equivalent to taking 83 million cars off the road. This is, however, a maximum possibility and the actual levels of carbon dioxide reduction are likely to be lower.

Impacts on farm income

GE technology has had a significant positive impact on farm income derived from a combination of enhanced productivity and efficiency gains. In 2014, the direct global farm income benefit from GE crops was $17.7 billion. This is equivalent to having added 7.2% to the value of global production of the four main crops of soybeans, maize, canola and cotton. Since 1996, farm incomes have increased by $150.3 billion.

Other Papers

A Meta-Analysis of the Impacts of Genetically Modified Crops (2014)

On average, GM technology adoption has reduced chemical pesticide use by 37%, increased crop yields by 22%, and increased farmer profits by 68%. Yield gains and pesticide reductions are larger for insect-resistant crops than for herbicide-tolerant crops. Yield and profit gains are higher in developing countries than in developed countries.

Economic impacts and impact dynamics of Bt (Bacillus thuringiensis) cotton in India (2012)

Building on unique panel data collected between 2002 and 2008, and controlling for nonrandom selection bias in technology adoption, we show that Bt has caused a 24% increase in cotton yield per acre through reduced pest damage and a 50% gain in cotton profit among smallholders. These benefits are stable; there are even indications that they have increased over time.

We further show that Bt cotton adoption has raised consumption expenditures, a common measure of household living standard, by 18% during the 2006–2008 period. We conclude that Bt cotton has created large and sustainable benefits, which contribute to positive economic and social development in India.

Bt cotton cuts pesticide poisoning (2011)

Over the past ten years that farmers in India have been planting Bt cotton – a transgenic variety containing genes from the soil bacterium Bacillus thuringiensis making it pest resistant – pesticide use has been cut by at least half, a new study shows.

The research also found that the use of Bt cotton helps to avoid at least 2.4 million cases of pesticide poisoning in Indian farmers each year, saving US$14 million in annual health costs.

Genetically Modified Crops and Food Security (2013)

We use comprehensive panel data collected over several years from farm households in India, where insect-resistant GM cotton has been widely adopted. Controlling for other factors, the adoption of GM cotton has significantly improved calorie consumption and dietary quality, resulting from increased family incomes. This technology has reduced food insecurity by 15–20% among cotton-producing households. GM crops alone will not solve the hunger problem, but they can be an important component in a broader food security strategy.